Need help diagnosing fueling issue from Open Road Race

Posted By: Uhcoog1

Need help diagnosing fueling issue from Open Road Race - 04/28/14 06:32 PM

I just got back from the Big Bend Open Road Race.

About 11 miles out from the finish, the AFR's spiked lean (22:1+ = lost fuel pressure to the rails). I pulled my foot out, got back in, did it again, pulled back out, waited a few seconds, and all was well when I got back in it. That happened every mile or so to the finish line. I had no other issues for the entire race (please note the second leg finish is straight and you're in the gas the entire time, while the first leg finish is not the same regarding throttle towards the finish line - there are a few corners that keep you from keeping your foot in it constant).

As far as I can tell, I still had about 6 gallons in the factory tank when this occurred.

My fuel system is as such:
-Factory style 1/2" pickup with fuel sock
-Carter 4600HP (100 gph low pressure). 1/2" in, 3/8" out.
-BC Bronco's 1 quart fuel accumulator (diesel fuel filter with pickup reaching to bottom of filter)
-Walbro GSL392 (mounted angled about even with the filter/accumulator)
-Wix 33737 corvette regulator/filter (under passenger seat)
-return line from regulator back to T above the BC Bronco's accumulator back to tank

I've had the lean spike happen before, on a road course, with very low fuel (sub 2-3 gallons) and a looong sweeper. Since then, I plan my fuel usage to never go below about 4-5 gallons on the road course and I haven't had a problem since.

Also, I had my original Walbro GSL392 fail on Wednesday of last week after the practice rounds and 60 mile drive back to the hotel. Ordered one overnight from summit, put it in, and that's what I ran the race with. I assumed it failed at 3,200 miles because I've ran it out of fuel once and had the issue on a road course with sweepers a few times.

I'm going to pull the filter/accumulator and see what I see. I'll also pull the pickup and get an idea as to if the sock is okay, etc. At this point, I'm curious if the root cause of my first pump failure and my losing fuel pressure at the end of the race may be related.

Possibilities:
-130 mph sustained causing fuel slosh that didn't allow the carter to keep up with walbro demand
-Dead-head system from under passenger seat to fuel rails causing issues
-'return' line into a T above the BC Bronco's fuel filter/accumulator may not actually allow much returned fuel from the corvette regulator into the accumulator

Anybody have any thoughts on this?

Also, I wasn't thrilled that the GSL392 failed at 3200 miles. How reliable is that pump (if I never run it dry)?

Here's a little diagram of my fuel system (diagram made by someone else).

Posted By: RylisPro

Re: Need help diagnosing fueling issue from Open Road Race - 04/28/14 06:47 PM

I really don't know much about fuel systems even though I just finished my fuel cell & have not run a track yet, but I would not use a filter as an accumulator. I would use a dedicated surge tank or swirl pot that holds a bigger volume of fuel than that little filter. Also I am a big fan of in-tank fuel pumps to keep them cool

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 04/28/14 07:34 PM

Quote:

I really don't know much about fuel systems even though I just finished my fuel cell & have not run a track yet, but I would not use a filter as an accumulator. I would use a dedicated surge tank or swirl pot that holds a bigger volume of fuel than that little filter. Also I am a big fan of in-tank fuel pumps to keep them cool

The filter is 1 quart, which is about 15-20 seconds at WOT with a 600 hp motor, or 35-40 seconds at part throttle. This accumulator option is one of the only ones I found that was meant for mounting under the car and not in the trunk. Also, the carter flows ~100 gph vs the walbro 65 gph, so under most cases the carter should be able to provide enough fuel as long as it can maintain flow 2/3rds of the time.

I was actually checking out your fuel tank install last night. That's a big expense item, that's for sure. I'm definitely going to pull a few part numbers and see what pricing I can get on a couple of the items.

Part of the reason I initially chose the set-up I did was it allowed everything to remain under the body (i.e. out of the trunk), was low cost, didn't require cutting or welding of the original tank, and theoretically would support my flow requirements. If I'm going to spend much more 'fixing' my current set-up, then I'm definitely going to look at all options.

If I had my way, I would get all of the following:
-Accumulator tank in main fuel cell/tank with trap doors
-pump located in accumulator tank, not external on a frame rail
-no fuel lines in trunk
-reasonable pricing

The current set up is the compromise I settled on.

Quick question/thought - I wonder if the GSL392 is having the 'suck' the fuel through the filter element at all? might be worth testing what the free flow rate of the carter is through the filter/accumulator to the GSL392 pickup point.

Also worth noting: The walbro gets louder the longer it's been on. Thoughts?

Posted By: ntstlgl1970

Re: Need help diagnosing fueling issue from Open Road Race - 04/29/14 12:19 AM

Did you measure the temp of the tank? I had a similar problem this year driving to MATS - boiled the fuel. I had no problems on the high speed track at willow springs. My system is (was) a return style system so it isn't quite the same as yours but I have a boxed sump in the stock tank where the -10 line goes in. The only reason I mention this is because you said that the pump got louder, my SX pump was doing the same thing, once it got loud, you only had a few minutes before it vapor locked. There were a number of people at MATS this year that had electric fuel pump issues. We had so many problems it took us 12 hours to get from LA to Vegas. Not fun. In Vegas, we added a pre supply (low pressure electric) pump right at the tank and had that feed the inlet of the main pump directly - the SX pump made no noise all the way home (9 hours). I pulled my entire external fuel system apart to replace with an in-tank pump using the corvette filter/regulator deadheaded to the engine like what you have. Seems like the in-tank pump is the only real solution to this issue.

Posted By: dangina

Re: Need help diagnosing fueling issue from Open Road Race - 04/29/14 12:27 AM

I'm not sure but shouldn't both pumps be the same? you have a return system, why have a low psi and a high psi one?

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 04/29/14 01:09 AM

Quote:

Did you measure the temp of the tank? I had a similar problem this year driving to MATS - boiled the fuel. I had no problems on the high speed track at willow springs. My system is (was) a return style system so it isn't quite the same as yours but I have a boxed sump in the stock tank where the -10 line goes in. The only reason I mention this is because you said that the pump got louder, my SX pump was doing the same thing, once it got loud, you only had a few minutes before it vapor locked. There were a number of people at MATS this year that had electric fuel pump issues. We had so many problems it took us 12 hours to get from LA to Vegas. Not fun. In Vegas, we added a pre supply (low pressure electric) pump right at the tank and had that feed the inlet of the main pump directly - the SX pump made no noise all the way home (9 hours). I pulled my entire external fuel system apart to replace with an in-tank pump using the corvette filter/regulator deadheaded to the engine like what you have. Seems like the in-tank pump is the only real solution to this issue.

Thanks for posting.

Any idea what contributed to your boiling fuel? It's very possible that I'm experiencing the same.

I stumbled across an aeromotive FAQ just now - almost describes my 'problem' to a T.

_____________________________________
After 30 minutes or so of driving, fuel pressure starts falling, then the fuel pump gets louder and/or seems to quit running altogether. The pump also seems hot to touch. What�s wrong?
You may be experiencing EFI vapor lock. Fuel system hot spots, the cause of vapor lock in carbureted engines of the past, and modern EFI engines where no return line is employed, are eliminated with the use of a bypass regulator placed after the fuel rail, in the engine compartment. Still, thanks to underhood engine heat, fuel in the EFI bypass system does slowly warm up as it is recycled through the fuel rail(s) and back to the tank. The longer an EFI engine runs, the higher fuel tank temperatures can become. Unlike the more common carburetor vapor lock, where fuel is heated to boiling in the float bowl(s) or fuel line(s) under the hood, EFI vapor lock is often caused by hot fuel in the tank and/or cavitation. Excess fuel pump noise combined with fluctuating and/or falling fuel pressure, often indicate cavitation is occurring. The exact point where gasoline changes from liquid to vapor depends on its temperature and pressure. A combination of high fuel temperature and low pressure are the primary cause of cavitation. In a return style EFI fuel system, the most likely place for these conditions to exist in the same place, at the same time, is at fuel pump inlet. The most common cause of cavitation is installation error. Once cavitation starts, it will feed upon itself. As vapor enters the pump, it displaces liquid fuel required to lubricate the mechanism, allowing metal to touch metal, creating even more friction and heat. Once the pump begins to super heat, a complete vapor lock may develop. In order to prevent cavitation and vapor lock, correct fuel system design and installation are vital. Ensure inlet filters meet hi-flow, low restriction requirements and that both inlet and outlet filters are kept clean. Keep the tank full on hot days. Reduce fuel pump speed during low load, idle and cruise conditions. Carefully route fuel lines and plan component placement to avoid exhaust heat. Do not overlook proper tank ventilation, if the vent line or vent valve do not allow ample air to move freely in both directions, fuel delivery problems will never fully resolve. Any conditions that restrict the pump�s access to fuel in the tank must be addressed. Read Tech Bulletin #101, Fuel Filtration and call the Aeromotive Tech Line if you need further assistance.
________________________________

The exhaust and rear end are very close in proximity to the fuel pumps and accumulator (it's all tucked in above the exhaust and rear end, zero airflow, etc). I may do a little low-buck heat shielding to see what I can do to help. Or, maybe I will re-locate everything away from the exhaust and rear end and try to get some airflow over the fuel system.

Further, I added a vent after the first pump failed. When pulling the gas cap, a significant amount of built up pressure would release. That also supports the overheated fuel theory.

What all causes fuel heating? Obviously hot pumps, etc- but I'm wondering if restrictions on my return system could be causing an issue as well. I might need to get my hands on a fuel pressure gauge or two to see what my pressures look like at different areas of the system.

Posted By: 72Swinger

Re: Need help diagnosing fueling issue from Open Road Race - 04/29/14 01:09 AM

Someone on LX forums said the stock deadhead setup is fine to 700hp. I would run your return direct to tank, I think your current setup is creating a lot of heat, and the Carter is probably inadequate for the sustained load of the Open road deal. I like the gss340 Walbro's up to 600hp but they're an in-tank pump. After that go to a Walbro 400 or twin 340's.

Posted By: PHJ426

Re: Need help diagnosing fueling issue from Open Road Race - 04/29/14 05:04 AM

If the system is pumping a large volume of fuel from atmospheric to high pressure that will put heat into the fuel. When your system is basically returning most of the fuel to the tank to be pressurized and returned to the tank it just grows the problem exponentially.

Where the intake systems use the fuel as a cooler for the electric fuel pump, just make sure not to make a habit of running it with low amounts of fuel in the tank.

Might be time for trying a fuel cooler in the return line? Not sure how high of a fuel pressure a cooler can work at but maybe install one there too in the high pressure side.

Posted By: ntsqd

Re: Need help diagnosing fueling issue from Open Road Race - 04/29/14 05:13 AM

How much pressure do you have between the filter and the HP pump? Some of the off-road user's of Chuck's accumulator have added a needle valve on the tank return to build some pressure in the accumulator and so that the LP pump has something to pump against and isn't free-wheeling. That will require some re-plumbing as the HP FRP's return shouldn't go thru that restriction. I know of a Holley Red that died from lack of something to push against while in the boonies. Fortunately we weren't too far from civilization and there were enough of us that a trail fix was soon remedied.

The Aeromotive thing hinted around the edges of something that I've seen to be fairly common off road. The suction side of any pump reduces the pressure on the fuel. That's obvious, what isn't so obvious is just how that affects the fuel. I looked into it once and failed to bookmark the relevant pages, but a seemingly small depression from atmospheric pressure on the fuel results in a surprisingly large lowering of the fuel's boiling point. I wish that I could recall the numbers, but as an example something like 1 psi pressure depression brought the average boiling point down to 80�F. Those aren't exact numbers, but they're surprisingly (scarily?) close!

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 04/29/14 05:14 PM

That's good info fellas. Thanks.

I'm going to turn on the pumps and take temperature readings of different components over time. Then I'll do the same while driving. That should help determine where the excessive heat is coming from. I'll report back with results

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 04/29/14 09:31 PM

Alright. Here's my data (all in degrees Fahrenheit):

0 min, 7.5-10 min, 17.5-20 min. 30 min. 40 min. 50 min. 1 hr.
Accumulator: 74.4 . 79.7. 82.0. 84.0-86.7. 84.7. 85.8. 88.1
Carter side top: 73.7. 82.7. 83.8. 82.0. 85.4. 87.0. 91.0.
Carter bottom: 75.2. 82.0. 82.9. 87.4. 84.9. 86.8. 88.7.
Tank: 75.0. 82.5. 82.9. 82.0-87.6. 84.7. 87.0. 89.7.
Walbro: 75.7. 82.0. 82.5. 83.8. 85.2. 85.4. 87.9.
Pickup: 75.2. 82.7. 83.4. 87.4. 87.0. 87.0. 87.9.
Wix: 74.3. 82.0. 82.9. 85.4. 85.8. 87.0. 88.1.

Further, at end of 1 hour, pumps still sound fine/ normal. Nothing is even warm to the touch. This is in contrast to the pumps getting louder after driving for an hour.

After I finished the test, I called Aeromotive and asked a few general questions. Here's a summary of what they told me (great help line, btw- will definitely bring them business in the future).

1- EPA regulations require minimal cranking when starting. Hence winter blend fuel has a higher concentration of lower boiling products in the blend.
2- 120* or less is a good rule of thumb to keep fuel temp under. Problems begin around 130-140* for a well designed fuel system.
3- most of the heat isn't generated by the pump(s) but instead by engine compartment, etc
4- ANY vacuum suction on inlet of pump drastically reduces the boiling point of the fuel at that point.
Also, he said they run a1000 pumps continuously on 3 gallon tanks and never generate enough heat to cavitate a pump.

Posted By: 72Swinger

Re: Need help diagnosing fueling issue from Open Road Race - 04/29/14 10:56 PM

One thing besides heat that will kill an inline pump, other than a Weldon pump, is having either air in the inlet side or a restriction in the inlet side. That will make the temp spike right now and kill a pump quick. Before you invest to much in another pump Wade seriously consider going to an in-tank setup IMO.

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 04/30/14 01:00 AM

Quote:

One thing besides heat that will kill an inline pump, other than a Weldon pump, is having either air in the inlet side or a restriction in the inlet side. That will make the temp spike right now and kill a pump quick. Before you invest to much in another pump Wade seriously consider going to an in-tank setup IMO.

I can agree with that. But I'm not willing to put an in-tank pump in a factory tank. So if I can't get it done with my current components and a minimal monetary investment, then I'll probably purchase a fuel safe fuel cell and put a surge tank in it with an in-tank pump. But that's probably $1500+ when it's all said and done, so I'm going to try everything with my current components before I jump down that rabbit hole.

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 04/30/14 04:04 PM

More data.

Did a running test this morning. Outdoor temp was 55 degrees (vs 95 degrees at race where I had the issue).

Temps taken at 0 min, after 10 min warmup, after 10 min hard run (4k-6k in 2nd gear back and forth at full throttle and braking for 10 min).
Accumulator: 76.2. 89. 107(93 within 3 min of sitting)
Carter: 76.2. 94. 113.
Muffler: 76.6. 220. 404. (220 within 3 min of sitting)
Rear: 76.6. 103. 143.

Based on the data, I'm positive heat shielding between the muffler/rear end and fuel system will solve my issue.

Posted By: PHJ426

Re: Need help diagnosing fueling issue from Open Road Race - 04/30/14 05:13 PM

http://www.bangshift.com/forum/forum/ban...oblem-or-nothat

What was your fuel level at race day? You might have mentioned earlier, is there any baffling in your fuel tank and its being drawn from the factory pickup tube?

At your given level of performance level and track configuration is it a possibility of actually aerating the fuel?

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 04/30/14 06:30 PM

Quote:

http://www.bangshift.com/forum/forum/ban...oblem-or-nothat

What was your fuel level at race day? You might have mentioned earlier, is there any baffling in your fuel tank and its being drawn from the factory pickup tube?

At your given level of performance level and track configuration is it a possibility of actually aerating the fuel?

Fuel level was ~5-6 gallons in the tank at that point in the race. I've run it lower on a road course with no ill effects (3-4 gallons), and even lower on the street (I've run it out of fuel before, and didn't have any issues until I actually ran out - I was looking for the lower limit). This is a 16 gallon tank, and I try to keep it between 4 gallons and 14 gallons for overly spirited driving. For this race, I believe I burned about 7 gallons (total =13-14 gallons) on the Southbound leg, then put 8 gallons (total = 14-15 gallons) in the tank for the return trip (i.e. - I had more gas in the tank when the problem occurred vs the previous trip southbound)

There is zero baffling in the stock tank. Carter 4600HP is drawing through the factory pickup location (1/2" pickup). Sock on pickup in tank.

Aeration is an interesting concern. I'm fairly confident that any aeration will work it's way to the top of the accumulator/filter, and be sent back to the main tank. The return is through the same factory pickup location with a twist - I have a T fitting on it that forces the returned fuel to the sides, as opposed to up, down, or straight in. I figured that was my best option for keeping the returned fuel from upsetting the fuel sitting at or around the pickup.

Some guys make accumulator tanks that have their inputs off-center and call the accumulator tanks 'swirl pots'. That's supposed to help avoid aeration.

At this point I think it was just the 'perfect storm' conditions for my fuel system. Winter grade 91 octane, 95* temps, high load for 59 miles = extra hot exhaust, 3000 ft elevation with 5000 ft density altitude, low enough fuel level to not be able to handle all the heat, minimal airflow around fuel system, close proximity to exhaust, etc etc.

In addition to the heat shielding, I'll probably run a full tank on both legs, and might go ahead and use 104 unleaded octane (or mix some in) for the run (should have a higher spectrum of boiling points vs 91 winter grade).

Posted By: Challenger 1

Re: Need help diagnosing fueling issue from Open Road Race - 04/30/14 08:31 PM

Quote:

Quote:

Did you measure the temp of the tank? I had a similar problem this year driving to MATS - boiled the fuel. I had no problems on the high speed track at willow springs. My system is (was) a return style system so it isn't quite the same as yours but I have a boxed sump in the stock tank where the -10 line goes in. The only reason I mention this is because you said that the pump got louder, my SX pump was doing the same thing, once it got loud, you only had a few minutes before it vapor locked. There were a number of people at MATS this year that had electric fuel pump issues. We had so many problems it took us 12 hours to get from LA to Vegas. Not fun. In Vegas, we added a pre supply (low pressure electric) pump right at the tank and had that feed the inlet of the main pump directly - the SX pump made no noise all the way home (9 hours). I pulled my entire external fuel system apart to replace with an in-tank pump using the corvette filter/regulator deadheaded to the engine like what you have. Seems like the in-tank pump is the only real solution to this issue.

Thanks for posting.

Any idea what contributed to your boiling fuel? It's very possible that I'm experiencing the same.

I stumbled across an aeromotive FAQ just now - almost describes my 'problem' to a T.

_____________________________________
After 30 minutes or so of driving, fuel pressure starts falling, then the fuel pump gets louder and/or seems to quit running altogether. The pump also seems hot to touch. What�s wrong?
You may be experiencing EFI vapor lock. Fuel system hot spots, the cause of vapor lock in carbureted engines of the past, and modern EFI engines where no return line is employed, are eliminated with the use of a bypass regulator placed after the fuel rail, in the engine compartment. Still, thanks to underhood engine heat, fuel in the EFI bypass system does slowly warm up as it is recycled through the fuel rail(s) and back to the tank. The longer an EFI engine runs, the higher fuel tank temperatures can become. Unlike the more common carburetor vapor lock, where fuel is heated to boiling in the float bowl(s) or fuel line(s) under the hood, EFI vapor lock is often caused by hot fuel in the tank and/or cavitation. Excess fuel pump noise combined with fluctuating and/or falling fuel pressure, often indicate cavitation is occurring. The exact point where gasoline changes from liquid to vapor depends on its temperature and pressure. A combination of high fuel temperature and low pressure are the primary cause of cavitation. In a return style EFI fuel system, the most likely place for these conditions to exist in the same place, at the same time, is at fuel pump inlet. The most common cause of cavitation is installation error. Once cavitation starts, it will feed upon itself. As vapor enters the pump, it displaces liquid fuel required to lubricate the mechanism, allowing metal to touch metal, creating even more friction and heat. Once the pump begins to super heat, a complete vapor lock may develop. In order to prevent cavitation and vapor lock, correct fuel system design and installation are vital. Ensure inlet filters meet hi-flow, low restriction requirements and that both inlet and outlet filters are kept clean. Keep the tank full on hot days. Reduce fuel pump speed during low load, idle and cruise conditions. Carefully route fuel lines and plan component placement to avoid exhaust heat. Do not overlook proper tank ventilation, if the vent line or vent valve do not allow ample air to move freely in both directions, fuel delivery problems will never fully resolve. Any conditions that restrict the pump�s access to fuel in the tank must be addressed. Read Tech Bulletin #101, Fuel Filtration and call the Aeromotive Tech Line if you need further assistance.
________________________________

The exhaust and rear end are very close in proximity to the fuel pumps and accumulator (it's all tucked in above the exhaust and rear end, zero airflow, etc). I may do a little low-buck heat shielding to see what I can do to help. Or, maybe I will re-locate everything away from the exhaust and rear end and try to get some airflow over the fuel system.

Further, I added a vent after the first pump failed. When pulling the gas cap, a significant amount of built up pressure would release. That also supports the overheated fuel theory.

What all causes fuel heating? Obviously hot pumps, etc- but I'm wondering if restrictions on my return system could be causing an issue as well. I might need to get my hands on a fuel pressure gauge or two to see what my pressures look like at different areas of the system.

Seems like the in-tank pump is the only real solution to this issue.

This is true, external electric fuel pumps are not the answer, no matter how tricked out it is.

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 04/30/14 09:23 PM

Quote:

Seems like the in-tank pump is the only real solution to this issue.

This is true, external electric fuel pumps are not the answer, no matter how tricked out it is.

Tell me why you believe this to be true.

Posted By: Mopar_Rich

Re: Need help diagnosing fueling issue from Open Road Race - 04/30/14 10:41 PM

There are several mistakes people make with inline pumps - but if you take care of these, inline pumps work fine.

1) They should be gravity fed! That means a bung in a sump welded to the bottom on the tank and the inline pump mounted below that. A bung by itself will still have issues if the bung is not installed in a sump or some other means to keep from sucking air.

2) Since many people don't bother to install a sump or some other means to eliminate the possibility of sucking air - even with a bung - never run the fuel tank below 1/2 full.

The real solution ... buy a good tank with an internal sump and the pump mounted in the tank.

Posted By: 72Swinger

Re: Need help diagnosing fueling issue from Open Road Race - 04/30/14 10:46 PM

A problem I had once was with push-n-lok hoses and I was burning up pumps. Come to find out I had a line on the suction side that basically had a one way check valve in it because upon hose assembly, with ALOT of oil, the fricken fitting turned into a potato peeler and peeled up the inner lining of the cheap push-n-lok hose. So if you blew through the line from the pump end it was all good but upon suction it would shut itself. This happened with all FAST supplied hoses and fittings. I was so pissed I sent it all back and luckily they refunded it all. Been in-tank ever since and will NEVER EVER RUN push-n-lok again.

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 12:09 AM

Quote:

There are several mistakes people make with inline pumps - but if you take care of these, inline pumps work fine.

1) They should be gravity fed! That means a bung in a sump welded to the bottom on the tank and the inline pump mounted below that. A bung by itself will still have issues if the bung is not installed in a sump or some other means to keep from sucking air.

2) Since many people don't bother to install a sump or some other means to eliminate the possibility of sucking air - even with a bung - never run the fuel tank below 1/2 full.

The real solution ... buy a good tank with an internal sump and the pump mounted in the tank.

This is in line with my thinking. The walbro GSL392 and the in tank GSS series are both gerotor design pumps. If neither has to lift fuel, neither are run dry, and neither get excessively hot, there shouldn't be a difference in performance, longevity, etc.

Posted By: Challenger 1

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 12:43 AM

Quote:

Quote:

Seems like the in-tank pump is the only real solution to this issue.

This is true, external electric fuel pumps are not the answer, no matter how tricked out it is.

Tell me why you believe this to be true.

Because there are too many heat sources to avoid externally, not really a good place on most cars to mount a external electric pump and have it gravity fed the whole time, harder to keep the sump covered when the line exits on one side of the tank verses a internal pump is in the center usually. The column of gas inside the tank helps create a positive inlet pressure for the internal pump. Which is also cooled by the gas in the tank.

There are more advantages to having it in the tank. Safety, cheaper, simpler and more. Good luck.

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 01:52 AM

Quote:

Quote:

Quote:

Seems like the in-tank pump is the only real solution to this issue.

This is true, external electric fuel pumps are not the answer, no matter how tricked out it is.

Tell me why you believe this to be true.

Because there are too many heat sources to avoid externally, not really a good place on most cars to mount a external electric pump and have it gravity fed the whole time, harder to keep the sump covered when the line exits on one side of the tank verses a internal pump is in the center usually. The column of gas inside the tank helps create a positive inlet pressure for the internal pump. Which is also cooled by the gas in the tank.

There are more advantages to having it in the tank. Safety, cheaper, simpler and more. Good luck.

Have you run an in tank pump in a factory Mopar tank?

I chose the external pumps with accumulator because it's dependable for road course work, it keeps the fuel system out of the trunk, and it's fairly cheap. The options for an in-tank conversion for a factory tank do not look nearly as dependable for what I'm doing.

If you've got a tank designed for an in-tank pump, then of course it's better and cheaper. But for a factory tank, it's not so clear cut.

Posted By: PHJ426

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 02:02 AM

On my old 72 Road Runner I was able to fit a Holley black pump in the passenger wheel well against the frame rail right in the path of the fuel line.

Not sure if A bodies have room in the wheel well.

Posted By: Challenger 1

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 02:08 AM

Quote:

Quote:

Quote:

Quote:

Seems like the in-tank pump is the only real solution to this issue.

This is true, external electric fuel pumps are not the answer, no matter how tricked out it is.

Tell me why you believe this to be true.

Because there are too many heat sources to avoid externally, not really a good place on most cars to mount a external electric pump and have it gravity fed the whole time, harder to keep the sump covered when the line exits on one side of the tank verses a internal pump is in the center usually. The column of gas inside the tank helps create a positive inlet pressure for the internal pump. Which is also cooled by the gas in the tank.

There are more advantages to having it in the tank. Safety, cheaper, simpler and more. Good luck.

Have you run an in tank pump in a factory Mopar tank?

I chose the external pumps with accumulator because it's dependable for road course work, it keeps the fuel system out of the trunk, and it's fairly cheap. The options for an in-tank conversion for a factory tank do not look nearly as dependable for what I'm doing.

If you've got a tank designed for an in-tank pump, then of course it's better and cheaper. But for a factory tank, it's not so clear cut.

No I haven't ran it yet, but I have installed one recently, last month in a E body tank.

Check out aeromotive stealth pumps. I invested in the smaller pump at $440 bucks. Everything needed to install it is included including a sump.

I do have a lot of fuel experience, not just talking up this pump because I bought one.

For electric fuel pumps in our old cars, inside the tank makes so much sense. And is cheaper over all and will out perform most external pumps supplied by stock tanks even with sumps road racing.

Posted By: ahy

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 02:31 AM

Since the problem happens with time and running hard it sounds like a heat problem + low pressure causing cavitation. Agree a sump good size bung and no restriction of a filter and housing passages will help. Also heat shielding. A full return style high pressure setup can help also, especially if the return line does not go by a lot of hot spots.

I wrestled with the rail mounted pump on my setup... including failure of the high pressure pump. I could put a charger on the battery and run the pump for hours in the shop and it was fine. Run it in hot weather for a while with maybe low fuel and it got very noisy.

The fix for me was an in tank pump with internal sump. Ricky's hot rod fixed me up with the +1" deep tank that fits in the stock location. Not cheap but it works. It carried me from IL to CA and back in 7 days including mountains, desert and a south to north run on the Silver State Classic route.

Posted By: 72Swinger

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 02:48 AM

I used a hanger kit from these guys.
http://www.tanksinc.com/index.cfm/page/ptype=product/product_id=84/mode=prod/prd84.htm
They have expanded their offerings a bunch since then. Good folks too.

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 02:59 AM

If I have another failure, I'll probably put in a fuel safe with in tank accumulator or similar.

I did a ton of searching the last few days. These were my favorite ideas other than the fuel safe. Pretty neat to use a factory truck fuel basket.

http://www.pirate4x4.com/forum/miscellaneous/1679962-buggy-fuel-tanks-right-way.html

And this fuel pump basket is ingenious:

http://www.pirate4x4.com/forum/20666410-post64.html

Posted By: 72Swinger

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 03:06 AM

This is my surge tank, if I was building it today I would make it about half as big.

Attached picture 8129742-006.JPG

Posted By: 72Swinger

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 03:09 AM

Another

Posted By: ntsqd

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 03:46 PM

I still want to know what the pressure going into the HP pump is during the worst case condition. If the filter is dropping the LP's output to near zero, then the HP will be pulling a vacuum in the line between the filter and it. Lowered pressure on the fuel plus a lot of heat plus winter fuel.....

Could be as simple as that filter is used up and needs to be replaced.

Would also be good to know what the pressure is in the line btwn the LP and the tank is during those conditions.

In 20 years of using Push-Lock/Barb-tite hose and fittings I've never seen that flapper happen, not even when using hose not designed for those fittings. Have seen it happen with generic fuel hose on generic barbed fittings. Condemning the whole system over a single failure is ludicrous.

Posted By: 72Swinger

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 04:02 PM

I didn't condemn the whole system, just the whole fuel system. Fast has switched vendors since this also. My main point here is check your lines, INTERNALLY, because to the naked eye they will appear normal.

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 04:30 PM

Quote:

More data.

Did a running test this morning. Outdoor temp was 55 degrees (vs 95 degrees at race where I had the issue).

Temps taken at 0 min, after 10 min warmup, after 10 min hard run (4k-6k in 2nd gear back and forth at full throttle and braking for 10 min).
Accumulator: 76.2. 89. 107(93 within 3 min of sitting)
Carter: 76.2. 94. 113.
Muffler: 76.6. 220. 404. (220 within 3 min of sitting)
Rear: 76.6. 103. 143.

Based on the data, I'm positive heat shielding between the muffler/rear end and fuel system will solve my issue.

Made some heat shielding with some thin sheet metal I had laying around and some leftover heat shielding tape.

Went out to do the same test as yesterday. Looks like I pushed it harder today and built more heat up. Muffler was 455 today vs. 404 yesterday, and it stayed hotter longer.

Here are the results:

Running test with heat shield. Repeat of yesterday. 55 degrees out at start. 0 min, 10 min warmup, 10 min hard running.
Accumulator: 73.0. 82.4. 105. Within 3 min- 97-98. Measuring side today vs bottom yesterday.
Wix: 73.5. 81. 95.
Muffler: 104. 260. 455. 3 min- 360.
Heat shield cover: 103. 270. 505.
Heat shield metal: 0. 107. 175.

Looks like a marginal improvement.

Posted By: Uhcoog1

Re: Need help diagnosing fueling issue from Open Road Race - 05/01/14 04:35 PM

Quote:

I still want to know what the pressure going into the HP pump is during the worst case condition. If the filter is dropping the LP's output to near zero, then the HP will be pulling a vacuum in the line between the filter and it. Lowered pressure on the fuel plus a lot of heat plus winter fuel.....

Could be as simple as that filter is used up and needs to be replaced.

Would also be good to know what the pressure is in the line btwn the LP and the tank is during those conditions.

I'll see about getting some sensors in a couple places in the system. I agree- I'd like to find the lowest pressure point and see what I can do to improve the situation.

I can get my hands on 0-30 psi and 0-100 psi sensors that will log on my megasquirt $30 each), but I'm not sure I've seen a sensor that will read vacuum (for tank to LP pump). Any thoughts on this?

Posted By: ntsqd

Re: Need help diagnosing fueling issue from Open Road Race - 05/02/14 06:58 AM

MAP sensor?

Posted By: 72Swinger

Re: Need help diagnosing fueling issue from Open Road Race - 05/02/14 06:30 PM

Try having the high pressure pump suck straight from tank and measure temps. The heat is either coming from the pump or the biggest restrictions. Or the exhaust to I guess.

Posted By: ntstlgl1970

Re: Need help diagnosing fueling issue from Open Road Race - 05/06/14 07:44 AM

Find someone with a fluke pressure sensor setup, I don't know what they use for their sensor, but it reads both pressure and vacuum and it is tolerant of fluid unlike most MAP sensors

Posted By: ntsqd

Re: Need help diagnosing fueling issue from Open Road Race - 05/09/14 02:15 AM

Curious that a MAP sensor isn't fluid tolerant given that it's ported to wet flow. I'm expecting there to be some degree of vacuum in the intended sampling spot, not pressure, but a MAP sensor that can read boost wouldn't be a bad call if that is the direction taken and I would suggest mimicking their normal mounting orientation.

EDIT: Maybe just something like this? No point in over-thinking things.
http://chucker54.stores.yahoo.net/vaprteki.html

Posted By: ntstlgl1970

Re: Need help diagnosing fueling issue from Open Road Race - 05/25/14 02:31 AM

I had a combination of problems that contributed to the boiling issue, proximity of fuel system components to the exhaust and the fuel picking up so much heat from the engine. I spent a lot of time and money on insulating tape along with heat shielding around anything near a heat source but the car continued to boil the fuel. After I removed all of the external fuel system parts, I found something in the pre-supply pump inlet screen, some of the fuel tank sealer I had used in my tank came apart (after 5 years and ~4k miles)and was partially plugging the screen. The thing that was weird is that before I added the pre-supply pump, I had checked the pre filter in front of the main pump and it was clean. Maybe there was just enough of that stuff loose inside the tank that it would start restricting the outlet from the sump. Who knows. We were lucky to make it home. I bought a new stock tank intending to put an in tank pump in a boxed sump, but at this point I think I am going to forget the electric pump in a stock tank and get something from Rick's or Fuel Safe so I don't have to worry about this BS anymore.

Attached picture 8154767-pump1.jpg

Posted By: ntstlgl1970

Re: Need help diagnosing fueling issue from Open Road Race - 05/25/14 02:42 AM

tank

Posted By: ntstlgl1970

Re: Need help diagnosing fueling issue from Open Road Race - 05/25/14 02:43 AM

surprise!

Posted By: keyser soze

Re: Need help diagnosing fueling issue from Open Road Race - 05/25/14 03:12 AM

If you don't mind me asking, what type of sealer did you use?

Posted By: Squirrel_Cat

Re: Need help diagnosing fueling issue from Open Road Race - 05/25/14 04:23 AM

Man that sucks!

Posted By: ntstlgl1970

Re: Need help diagnosing fueling issue from Open Road Race - 05/25/14 08:43 PM

the sealer was POR-15 fuel tank sealer. but to be fair, the instructions said the best prep was to have the tank boiled - which I did not do - and second best was to wash it out with a few different cleaners - which I did. At this point, even if i was to get the tank boiled out, I'm not sure all the sealer would come out of there.

Posted By: PHJ426

Re: Need help diagnosing fueling issue from Open Road Race - 05/26/14 06:43 AM

Quote:

Find someone with a fluke pressure sensor setup, I don't know what they use for their sensor, but it reads both pressure and vacuum and it is tolerant of fluid unlike most MAP sensors

If you have any contacts that know people in instrumentation and process controls they will have this or something like this calibrator. Could also have data logging capabilities.