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Still having to prime my carb to get my car to start #2570332
10/27/18 08:04 PM
10/27/18 08:04 PM
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Sixt8Chrgr Offline OP
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This is getting real old. I thought the fuel pump was bad. Changed out the Precision Pump for a nice Carter M6903. Still when the car has sat for a long time the pump is not getting fuel to the carb while trying to start it. Only after the car fires after the carb is primed does the pump have enough pressure to get the fuel to the carb. Car is freshly restored except for the fuel sending unit.

Could it be the fuel vapor canister? This is new

Bad fuel sending unit? I did not replace this when I restored the car.

Thanks

Lawrence

Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570344
10/27/18 08:30 PM
10/27/18 08:30 PM
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dragon slayer Offline
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What is a fuel sending unit? Cars can do this. Some add an electric pump to prime the carbs before starting.

You can break the fuel fitting after the pump and vapor cannister at the carb. Crank car and see if you get fuel out of line. Even measure pressure if you have a gauge. If not some thing amiss and work your way back to the pump.

But it can take a long time to prime the carb(s) and line when the car sits and the fuel evaporates.

Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570348
10/27/18 08:40 PM
10/27/18 08:40 PM
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Hamtramck, PA
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When these cars sit, the fuel evaporates from the bowl.

What you have described is very normal.

I use an old mustard bottle properly cleaned & filled with gas to refill the carburetor via the vent tube.

Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570362
10/27/18 09:04 PM
10/27/18 09:04 PM
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Cincinnati, Ohio
Challenger 1 Offline
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Yes I bet the sock on your pickup in the tank is dirty if you have not checked it.

I have a 440 and a 340 with stock mechanical fuel pumps and fresh socks in the tanks. They both start after sitting for months. Yes I have to crank them for 15-20 seconds while pumping the gas petal but they start consistently for more than 10 years now. The 440 has a 6 pak and the 340 has a edlebrock 600 on it with mechanical chokes that work. The chokes help too. I haven't had the air cleaners off in years literally.

Besides the sock check for any rust, even the smallest pin hole will cause problems starting in your steel suction line. Can't have any leaks in your suction line, check it.

Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570385
10/27/18 09:59 PM
10/27/18 09:59 PM
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Florida
cbusters Offline
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I have the same problem. I think my AVS has leaking plugs on the bottom of the carb.

Re: Still having to prime my carb to get my car to start [Re: cbusters] #2570391
10/27/18 10:19 PM
10/27/18 10:19 PM
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Cincinnati, Ohio
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Stock air cleaners do better than open air filters, IMO because there is less evaporation. I used to have the usual chrome open air air filter on my car. Then went back to stock on the air cleaner and I think it helps with evaporation.

This car sat at home outside under a awning for the last 4-5 years. I haven't started it since about May of this year. I fired it up just a few days ago to drive it down to my hanger for the winter, probably permanent home. 20-30 seconds of cranking and it fired up. I am telling you the choke helps a bunch. I did not even open the hood until I got to the hanger and was checking for mouse nests since I haven't driven it since Jan of this year in the snow and ice/salt.


Wife and doggy.



Last edited by Challenger 1; 10/27/18 10:37 PM.
Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570397
10/27/18 10:31 PM
10/27/18 10:31 PM
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Morristown Tn.
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71birdJ68 Offline
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Just the way gas is now a days. If my car sits more than 2 days I have to crank it to fill the bowls.

Last edited by 71birdJ68; 10/28/18 12:07 AM.
Re: Still having to prime my carb to get my car to start [Re: 71birdJ68] #2570401
10/27/18 10:42 PM
10/27/18 10:42 PM
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Cincinnati, Ohio
Challenger 1 Offline
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Got a different hanger this week, the car fired up in 10 seconds instead of 20 seconds. I plan to drive it much more now, too cloudy to fly? Then I drive the muscle car around the block for stress relief.

Re: Still having to prime my carb to get my car to start [Re: dragon slayer] #2570430
10/28/18 12:24 AM
10/28/18 12:24 AM
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Sixt8Chrgr Offline OP
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Originally Posted By dragon slayer
What is a fuel sending unit? Cars can do this. Some add an electric pump to prime the carbs before starting.

You can break the fuel fitting after the pump and vapor cannister at the carb. Crank car and see if you get fuel out of line. Even measure pressure if you have a gauge. If not some thing amiss and work your way back to the pump.

But it can take a long time to prime the carb(s) and line when the car sits and the fuel evaporates.
[i][/i]

Fuel pick up in the tank with the sock is what I should had said. What my car is doing is not normal. It did not do this prior to the resto and the fuel vapor canister. I did re use the fuel pick up and should had changed it.

I did take the fuel line off the carb after cranking if for a long time and it was bone dry. Did the same with the line off the carb and had the line in a bottle...no fuel. Did not crank real long though. Since the fuel gauge is not 100% correct might as well change out the gauge sending/pick up with a new sock and see if that fixes it

Re: Still having to prime my carb to get my car to start [Re: Challenger 1] #2570431
10/28/18 12:26 AM
10/28/18 12:26 AM
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Sixt8Chrgr Offline OP
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Originally Posted By Challenger 1
Yes I bet the sock on your pickup in the tank is dirty if you have not checked it.

I have a 440 and a 340 with stock mechanical fuel pumps and fresh socks in the tanks. They both start after sitting for months. Yes I have to crank them for 15-20 seconds while pumping the gas petal but they start consistently for more than 10 years now. The 440 has a 6 pak and the 340 has a edlebrock 600 on it with mechanical chokes that work. The chokes help too. I haven't had the air cleaners off in years literally.

Besides the sock check for any rust, even the smallest pin hole will cause problems starting in your steel suction line. Can't have any leaks in your suction line, check it.


Will do thanks

Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570509
10/28/18 09:56 AM
10/28/18 09:56 AM
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jt4406 Offline
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Agree with all the "above", but would like to add: check length of your fuel pump push rod against a known good one (this fooled me recently) and seems I remember reading that some of the repop six pack vapor canisters had a return orifice that was too large? May be worth looking at if your pickup sock and fuel pump pushrod prove to be good. jess


Yeah, it's hopped up to over 160...
Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570566
10/28/18 01:04 PM
10/28/18 01:04 PM
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Phila. Pa.
Mattax Offline
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Only thing to add is there should be some fuel in bowl when first starting.
It should not need the fuel pump to run to refill it. There should be enough fuel in the bowl to start and run it for a minute or so.

Quick check: Remove air cleaner lid and see if the accelerator pump shoots fuel out.
If yes. Do it again to see if there's enough fuel in bowl to refill the pump.
If no. remove top of carb to see if there is fuel in the bowl.
If yes, accel pump may need new seal or check valve.
If no, its either weeping out or evaporating.

Also, just know there's several service bulletins in 70s addressing the issues of starting. Some models got an internal bypass in the pump which helped hot starting but made cold starting more difficult.
http://www.imperialclub.org/Repair/Lit/Master/307/index.htm

Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570571
10/28/18 01:16 PM
10/28/18 01:16 PM
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Texas Hill Country
Centerline Offline
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Today's Ethanol laced fuels evaporate at a much higher rate than normal "gas" and that is your problem. If you let the car set for more than a week all the fuel in the carb will evaporate and you wind up having to crank the engine for a while to fill the bowls again. You don't find this problem with fuel injected cars since they all use electric pumps and run on high pressure. You also won't find this problem with a carburetor setup when using an electric pump.

With the crap we have for fuel now days you basically have three choices. Change to an electric pump and eliminate the mechanical pump, add an electric pump with a check valve to bypass the mechanical pump so you can fill the bowls before starting, or fill the bowls manually before starting.

Those are pretty much your options. Good luck.


Centerline
64 Dodge Polara 426 Street Wedge - For when I want to go fast
99 Corvette Z-06 - For when I want to turn corners
Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570596
10/28/18 02:32 PM
10/28/18 02:32 PM
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Phila. Pa.
Mattax Offline
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Actually, only the light end evaporates faster. T50 is about the same and T90 is generally higher than pre-RFG. Thats why there should still be fuel bowl if not the accel pump itself.

Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570608
10/28/18 03:09 PM
10/28/18 03:09 PM
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Rio Linda, CA
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Do modern cars have this problem? No. Do modern cars have carburetors? No. The answer to the OP's problem lies here, modern fuel is gonna evaporate from open reservoirs.


The INTERNET, the MISinformation superhighway
Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570618
10/28/18 03:35 PM
10/28/18 03:35 PM
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Oregon
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AndyF Offline
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Gas is formulated for EFI these days. Nobody has sold a new car with a carb for at least 30 years. It is only going to get worse so I switched all of my stuff over to EFI.

Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2570649
10/28/18 04:42 PM
10/28/18 04:42 PM
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Phila. Pa.
Mattax Offline
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Not actually true. Its formulated to meet a lot of different requirements, some of which vary by state, region, and season. EFI has an advantage in two ways. Its less sensistive to RVP because the system is mostly closed (less so with TBI) and feedback loops can compensate mix and timing to some extent for variations.

The T50 is pretty much the same as its always been. You can blame the RFG for the first 20% evaporated being worse than 25 years ago but not the rest.

Re: Still having to prime my carb to get my car to start [Re: jt4406] #2570721
10/28/18 08:53 PM
10/28/18 08:53 PM
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Originally Posted By jt4406
Agree with all the "above", but would like to add: check length of your fuel pump push rod against a known good one (this fooled me recently) and seems I remember reading that some of the repop six pack vapor canisters had a return orifice that was too large? May be worth looking at if your pickup sock and fuel pump pushrod prove t.. be good. jess
this... got me new push rod was the fix !

Re: Still having to prime my carb to get my car to start [Re: ink] #2570759
10/28/18 10:18 PM
10/28/18 10:18 PM
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Hinckley, Ohio
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Originally Posted By ink
Originally Posted By jt4406
Agree with all the "above", but would like to add: check length of your fuel pump push rod against a known good one (this fooled me recently) and seems I remember reading that some of the repop six pack vapor canisters had a return orifice that was too large? May be worth looking at if your pickup sock and fuel pump pushrod prove t.. be good. jess
this... got me new push rod was the fix !


Same here. If the car hadn't been started for an extended time period (maybe a week or two - can't remember) then no matter how long I cranked the engine it would not start. To get the engine to start I also had to manually prime the carb. I eventually found that the push rod was worn and once replaced the problem was gone.

Last edited by KWF340; 10/28/18 10:30 PM.

1968 Charger R/T, 440 Auto, GG1;
1969 Super Bee, 383, 4-speed, T5;
1969.5 Road Runner, 440-6, 4-speed, 96;
1970 Duster 340, 4-speed, EV2;
1970 Charger R/T SE, 440 (496), Auto, EB3;
1970 Dart Swinger 340 (416), 4-speed, EV2;
1970 Corvette coupe, LS5, 4-speed, Daytona yellow;
2000 Corvette coupe, LS1, 6-speed, Twin Turbo, Torch red.
Re: Still having to prime my carb to get my car to start [Re: Sixt8Chrgr] #2571095
10/29/18 05:12 PM
10/29/18 05:12 PM
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Motor City
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6PKRTSE Offline
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3RD vote for a fuel pump push rod being worn. I had this problem before on one of my other Hemi's when it sat for a period of time. Seems it would not give it large enough pump shot while cranking. Once fired it would idle & run fine. Once it changed out for a new push rod the problem went away & start right up every time afterwards. Even seemed to pull harder at higher RPM also, so it must have been losing fuel pressure at high RPM's also.


1963 Belvedere 440 Max Wedge Tribute
1970 Charger R/T S.E. 440 Six Pack
1970 Challenger R/T, 528 Hemi
1970 Charger 500 S.E. 440 4 BBL
1970 Plymouth Road Runner 383
1974 Chrysler New Yorker 440
1996 2500 RAM 488 V-10 4X4
2004 3500 Dually Cummins 4x4
2012 Challenger R/T Classic.
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