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Re: Returnless EFI Question [Re: Bad340fish] #2258766
02/24/17 03:42 PM
02/24/17 03:42 PM
Joined: Jan 2011
Posts: 15,713
Central Florida
larrymopar360 Offline
Stud Muffin
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Central Florida
I have no room for spacer but do have an Eddy Air Gap intake so hopefully that helps some. Mine is throttle body. I haven't driven it much yet. Just haven't had a chance, but I'm dying to drive it more. Haven't heard the pump yet, but then might with more driving. I live in Florida so it's going to be hot, hot, hot in the Summer. From what you're saying, I guess I may be ok though, other than some pump noise when it's really hot? Thank you for information.


Facts are stubborn things.
Re: Returnless EFI Question [Re: jbc426] #2258784
02/24/17 04:13 PM
02/24/17 04:13 PM
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Posts: 354
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kielbasa Offline OP
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The return regulators near the tank with a deadhead line to the engine compartment are nice, but it is still much better to use PWM to control and match the power to the pump to engine demand in any of these systems. [/quote]

Wondering if this variable pump output is a fairly new development, or has automotive been doing this for some time? If so, do all cars use this type of fuel pump system, or limited to high end and/or expensive cars?

Re: Returnless EFI Question [Re: Bad340fish] #2258951
02/24/17 10:13 PM
02/24/17 10:13 PM
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Posts: 28,312
Cincinnati, Ohio
Challenger 1 Offline
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Cincinnati, Ohio
Originally Posted By Bad340fish
Two pumps for redundancy, and with my EFI I can stage them. I run one pump all the time of course then at greater than 60% throttle and over 3000RPM the computer will kick the second pump on. It will run on one pump but its pretty close to its limits at 550ish HP so the second pump is there for insurance. Plus in the event of a pump failure on the road I can move one wire in the back to turn the secondary pump into the primary pump.

Just something I did to keep a 10 second street car reliable when travelling the back roads of the Midwest on drag week.


Sounds pretty slick, cool idea! I understand wanting to be prepared and then some. Good luck with it! up

Re: Returnless EFI Question [Re: kielbasa] #2259180
02/25/17 12:13 PM
02/25/17 12:13 PM
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo Offline
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Originally Posted By kielbasa


Wondering if this variable pump output is a fairly new development, or has automotive been doing this for some time? If so, do all cars use this type of fuel pump system, or limited to high end and/or expensive cars?


Fairly recent and limited to high end/high output cars. I would bet the reason for it is that much fuel requires a big pump, and reducing output via pwm is more to do with lowering noise and extending pump life by running the motor slower than it is anything to do with fuel heat.

Re: Returnless EFI Question [Re: kielbasa] #2259319
02/25/17 04:29 PM
02/25/17 04:29 PM
Joined: Jan 2003
Posts: 8,005
Tulsa OK
Bad340fish Offline
master
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Tulsa OK
I know my megasquirt can PWM the pump but I haven't messed with it much yet. It looks like a pretty simple table. I need to add a solid state relay before I can proceed any further.

Screen Shot 2017-02-25 at 11.45.07 AM.png

68 Barracuda Formula S 340
87 "Chrysler" Conquest
Re: Returnless EFI Question [Re: kielbasa] #2259508
02/25/17 10:54 PM
02/25/17 10:54 PM
Joined: Mar 2007
Posts: 3,275
West Coast, USA
jbc426 Offline
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Originally Posted By kielbasa


The return regulators near the tank with a deadhead line to the engine compartment are nice, but it is still much better to use PWM to control and match the power to the pump to engine demand in any of these systems.


Wondering if this variable pump output is a fairly new development, or has automotive been doing this for some time? If so, do all cars use this type of fuel pump system, or limited to high end and/or expensive cars? [/quote]

The concept has been around for decades, but actual PWM in production cars seems to be a relatively recent development. There's not much history about it found in a surface search of the web.

Most modern production vehicles use PWM to control the fuel pumps for several reasons including increasing pump life and reducing the heating effect in the fuel tank especially at low volumes. Most factory in-tank EFI pumps are pretty quiet by design and placement. Even smaller displacement low-end cars use this technology, but it is the high flow, high output systems that really benefit from the technology.


1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
Re: Returnless EFI Question [Re: DaytonaTurbo] #2259654
02/26/17 05:40 AM
02/26/17 05:40 AM
Joined: Jan 2003
Posts: 27,421
Balt. Md
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383man Offline
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Originally Posted By DaytonaTurbo
Originally Posted By jbc426

A high flow pump running at full output all the time, especially against a dead head regulator generates a lot of heat.


We're not talking about dead head regulators. The ones in question are return style regulators mounted near the tank so you have a "returnless" fuel line feeding the engine bay.



Its funny you said this as I remember in 1992 when Mopar went to a returnless EFI system and thats about when I started seeing the fuel filters on the Caravans mounted by the tank with a third line that was a return to the tank. And of course it had no return line of regulator up front. Mopar told us that the PCM was now smart enough and worked fast enough that when you stepped on the gas pedal fast the PCM could increase the pulse width fast enough that it did not need the higher fuel pressure anymore that the vacum controlled press regulator gave it when manifold vacum dropped. At that time they did put the fuel pump on its own relay but it still fed the pump a solid 12 volts through its relay and it's relay shared its ground at the PCM with the shutdown relay so it did not pulse width the pump to change its speed or pressure. I remember in training at that time in 1992 when Mopar first used the returnless system and eliminated the vacum fed press regulator they just told us that the PCM worked fast enough that it did not need the vacum fed pres regulator as the PCM could increase inj pulse width fastenough to handle it. Ron

Re: Returnless EFI Question [Re: kielbasa] #2260194
02/26/17 11:54 PM
02/26/17 11:54 PM
Joined: Jan 2003
Posts: 1,482
Lake Orion, MI
goldduster318 Offline
pro stock
goldduster318  Offline
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Posts: 1,482
Lake Orion, MI
I have an Aeromotive Phantom 340 system, which is basically their 340lph pump, return system - feeds rails then to regulator and the return, -6 (3/8) feed and return. No fuel heating issues or any issues of any kind. Pump is quiet as well. Easily feeds the 470hp engine.

The PWM is wholly unnecessary, its a "cost saving" idea at the OEMs. Even the corvette style one, you could change your fuel filter and the tolerance could jack with your fueling (bad parts out there).

You don't want to PWM just any fuel pump either.

So, In tank pump and return style is what I would recommend anytime.


'70 Duster 470hp 340/T56 Magnum/8 3/4 3.23 Sure-Grip
Re: Returnless EFI Question [Re: goldduster318] #2260246
02/27/17 01:14 AM
02/27/17 01:14 AM
Joined: Mar 2007
Posts: 3,275
West Coast, USA
jbc426 Offline
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Originally Posted By goldduster318
I have an Aeromotive Phantom 340 system, which is basically their 340lph pump, return system - feeds rails then to regulator and the return, -6 (3/8) feed and return. No fuel heating issues or any issues of any kind. Pump is quiet as well. Easily feeds the 470hp engine.

The PWM is wholly unnecessary, its a "cost saving" idea at the OEMs. Even the corvette style one, you could change your fuel filter and the tolerance could jack with your fueling (bad parts out there).

You don't want to PWM just any fuel pump either.

So, In tank pump and return style is what I would recommend anytime.


Trying to understand this, so a low tech return system worked on your low HP ride with no noticeable issues, then you out think an entire industry in your spare time and gratuitously post your conclusions based on this one experience alone potentially misleading countless readers? Interesting extrapolation based on one result. Keep up the good work.


1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
Re: Returnless EFI Question [Re: jbc426] #2260792
02/27/17 11:44 PM
02/27/17 11:44 PM
Joined: Jan 2003
Posts: 1,482
Lake Orion, MI
goldduster318 Offline
pro stock
goldduster318  Offline
pro stock

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Posts: 1,482
Lake Orion, MI
Originally Posted By jbc426
Originally Posted By goldduster318
I have an Aeromotive Phantom 340 system, which is basically their 340lph pump, return system - feeds rails then to regulator and the return, -6 (3/8) feed and return. No fuel heating issues or any issues of any kind. Pump is quiet as well. Easily feeds the 470hp engine.

The PWM is wholly unnecessary, its a "cost saving" idea at the OEMs. Even the corvette style one, you could change your fuel filter and the tolerance could jack with your fueling (bad parts out there).

You don't want to PWM just any fuel pump either.

So, In tank pump and return style is what I would recommend anytime.


Trying to understand this, so a low tech return system worked on your low HP ride with no noticeable issues, then you out think an entire industry in your spare time and gratuitously post your conclusions based on this one experience alone potentially misleading countless readers? Interesting extrapolation based on one result. Keep up the good work.


Wow, thanks for your really really nice reply. Of course, its not like the people who make the fuel pumps also agree with me or anything:
https://www.aeromotiveinc.com/tech-help/faqs/faq-340-stealth-fuel-pumps/
(read line item #6). While they do say you can use a returnless system with a PWM, it's with some caution and doesn't work well with just any pump. Of course I may not have spoken properly and said returnless at the right time.

Funny thing is I work in the auto industry, and I also know what their motivations are. If they can get by with less plumbing, they will. Because the connections cause more assembly problems (cross thread, strip, leaks, more connections to be made during assembly, etc) than plugging in some modules. They are also making the car for one application, not the wildly varying applications that would be used on people's mild to wild modified cars.

The theory of a return system is a lot less complicated, fuel flows from the pump, into the rails, over the injectors, and then the regulator, controlled by a simple spring returns the unused fuel to the tank. Please tell me how this is a bad thing? Provided the pump can keep up with the fuel demands, you don't ever run out of fuel. No worry about hydraulic delay, and the pressure is controlled nearer to the injectors.

The corvette filter just uses a sized orifice to return fuel to the tank instead of a spring...and a small one at that. So if the size is off (low quality part), the pressure can change.

I'd be extremely shocked for anyone to have fuel heating problems with a return system and an in-tank pump. The OEMs also made systems exactly like this for years. Low-tech isn't always bad. I'm not misleading anyone. The higher the HP a modified car is, the more likely you are to see a return system regardless of what it came with. But hey, do what you want, I'd rather see someone run some extra line then spend a lot of money on something they may not be able to troubleshoot easily. The extra line and having a regulator in the engine bay is really the only downside of a return system.

Last edited by goldduster318; 02/27/17 11:45 PM.

'70 Duster 470hp 340/T56 Magnum/8 3/4 3.23 Sure-Grip
Re: Returnless EFI Question [Re: goldduster318] #2261010
02/28/17 01:20 PM
02/28/17 01:20 PM
Joined: Jan 2003
Posts: 15,197
Omaha Ne
T
TJP Offline
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Omaha Ne
Originally Posted By goldduster318
Originally Posted By jbc426
Originally Posted By goldduster318
I have an Aeromotive Phantom 340 system, which is basically their 340lph pump, return system - feeds rails then to regulator and the return, -6 (3/8) feed and return. No fuel heating issues or any issues of any kind. Pump is quiet as well. Easily feeds the 470hp engine.

The PWM is wholly unnecessary, its a "cost saving" idea at the OEMs. Even the corvette style one, you could change your fuel filter and the tolerance could jack with your fueling (bad parts out there).

You don't want to PWM just any fuel pump either.

So, In tank pump and return style is what I would recommend anytime.


Trying to understand this, so a low tech return system worked on your low HP ride with no noticeable issues, then you out think an entire industry in your spare time and gratuitously post your conclusions based on this one experience alone potentially misleading countless readers? Interesting extrapolation based on one result. Keep up the good work.


Wow, thanks for your really really nice reply. Of course, its not like the people who make the fuel pumps also agree with me or anything:
https://www.aeromotiveinc.com/tech-help/faqs/faq-340-stealth-fuel-pumps/
(read line item #6). While they do say you can use a returnless system with a PWM, it's with some caution and doesn't work well with just any pump. Of course I may not have spoken properly and said returnless at the right time.

Funny thing is I work in the auto industry, and I also know what their motivations are. If they can get by with less plumbing, they will. Because the connections cause more assembly problems (cross thread, strip, leaks, more connections to be made during assembly, etc) than plugging in some modules. They are also making the car for one application, not the wildly varying applications that would be used on people's mild to wild modified cars.

The theory of a return system is a lot less complicated, fuel flows from the pump, into the rails, over the injectors, and then the regulator, controlled by a simple spring returns the unused fuel to the tank. Please tell me how this is a bad thing? Provided the pump can keep up with the fuel demands, you don't ever run out of fuel. No worry about hydraulic delay, and the pressure is controlled nearer to the injectors.

The corvette filter just uses a sized orifice to return fuel to the tank instead of a spring...and a small one at that. So if the size is off (low quality part), the pressure can change.

I'd be extremely shocked for anyone to have fuel heating problems with a return system and an in-tank pump. The OEMs also made systems exactly like this for years. Low-tech isn't always bad. I'm not misleading anyone. The higher the HP a modified car is, the more likely you are to see a return system regardless of what it came with. But hey, do what you want, I'd rather see someone run some extra line then spend a lot of money on something they may not be able to troubleshoot easily. The extra line and having a regulator in the engine bay is really the only downside of a return system.


Well said, bow beer

Re: Returnless EFI Question [Re: goldduster318] #2261031
02/28/17 01:54 PM
02/28/17 01:54 PM
Joined: Mar 2007
Posts: 3,275
West Coast, USA
jbc426 Offline
master
jbc426  Offline
master

Joined: Mar 2007
Posts: 3,275
West Coast, USA
Originally Posted By goldduster318
Originally Posted By jbc426
Originally Posted By goldduster318
I have an Aeromotive Phantom 340 system, which is basically their 340lph pump, return system - feeds rails then to regulator and the return, -6 (3/8) feed and return. No fuel heating issues or any issues of any kind. Pump is quiet as well. Easily feeds the 470hp engine.

The PWM is wholly unnecessary, its a "cost saving" idea at the OEMs. Even the corvette style one, you could change your fuel filter and the tolerance could jack with your fueling (bad parts out there).

You don't want to PWM just any fuel pump either.

So, In tank pump and return style is what I would recommend anytime.


Trying to understand this, so a low tech return system worked on your low HP ride with no noticeable issues, then you out think an entire industry in your spare time and gratuitously post your conclusions based on this one experience alone potentially misleading countless readers? Interesting extrapolation based on one result. Keep up the good work.


Wow, thanks for your really really nice reply. Of course, its not like the people who make the fuel pumps also agree with me or anything:
https://www.aeromotiveinc.com/tech-help/faqs/faq-340-stealth-fuel-pumps/
(read line item #6). While they do say you can use a returnless system with a PWM, it's with some caution and doesn't work well with just any pump. Of course I may not have spoken properly and said returnless at the right time.

Funny thing is I work in the auto industry, and I also know what their motivations are. If they can get by with less plumbing, they will. Because the connections cause more assembly problems (cross thread, strip, leaks, more connections to be made during assembly, etc) than plugging in some modules. They are also making the car for one application, not the wildly varying applications that would be used on people's mild to wild modified cars.

The theory of a return system is a lot less complicated, fuel flows from the pump, into the rails, over the injectors, and then the regulator, controlled by a simple spring returns the unused fuel to the tank. Please tell me how this is a bad thing? Provided the pump can keep up with the fuel demands, you don't ever run out of fuel. No worry about hydraulic delay, and the pressure is controlled nearer to the injectors.

The corvette filter just uses a sized orifice to return fuel to the tank instead of a spring...and a small one at that. So if the size is off (low quality part), the pressure can change.

I'd be extremely shocked for anyone to have fuel heating problems with a return system and an in-tank pump. The OEMs also made systems exactly like this for years. Low-tech isn't always bad. I'm not misleading anyone. The higher the HP a modified car is, the more likely you are to see a return system regardless of what it came with. But hey, do what you want, I'd rather see someone run some extra line then spend a lot of money on something they may not be able to troubleshoot easily. The extra line and having a regulator in the engine bay is really the only downside of a return system.


Fuel only needs to exceed about 120* to cavitate. That's cooler than a cup of McDonalds coffee. A high flow pump puts out the heat energy of a 240 watt light bulb. Being in the automotive industry, you likely don't run your fuel low in your tank as a general practice for a reason.

A quick search of the internet may be even more shocking on this topic. Even Aeromotive discusses overheating pumps in there literature, and well-designed bypass regulators help dramatically.

There are always exceptions, and in general for low performance systems you are right. But, electric pumps introduce heat into the fuel systems without exception. They are cooled by the fuel by design. This means they transfer the heat the produce into the fuel. Whether or not it becomes an issue depends on many factors, but this can be an issue when high flow pumps aren't voltage limited using PWM during periods of low fuel demand.


1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
Re: Returnless EFI Question [Re: kielbasa] #2261053
02/28/17 02:36 PM
02/28/17 02:36 PM
Joined: Aug 2011
Posts: 2,843
Pattison Texas
CSK Offline
master
CSK  Offline
master

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Posts: 2,843
Pattison Texas
Fuel return is the best set up,my opinion, but what do I know, the temps down here in Southeast Texas get above 100 on a regular basis & underhood temps are very high,fuel return works well.


1968 Charger COLD A/C Hilborn EFI
512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim
2020 T/A 392 Stock 11.79 @ 114.5

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