Best place for inline EFI fuel pump?

[mouserider]

Hey forum, i have sniper 2x4 setup on my charger 1971 with holley inline fuel pump, and i do have fuel delivery problem, pump is good for my application, we(me and one sniper efi expert) thinks thats the fuel pump dont get enough flow in. My pump is located right under passenger seat in the lowest possible point, however the lines that goes from the tank are going around the diff following the curve of diff arch, and highest point of this arch is obviously higher than the tank, i assume that prevents fuel pump to be gravity fed. there 2 are ways to deal with it, change lines so they form a straight downhill path to the pump (but i cant imagine how to do it to avoid diff curve) or to relocate the pump closer to the tank before diff, but i cant see a single point that is lower then tank, tank is lowest in the back of the car.

Also i cant really understand the physics of the fuel flow, since the sending unit is not at the bottom of the tank, but in the middle, should the pump be lower then sending unit location or lower than bottom of the tank?

thank you

 

[vance.dykes]

a in-tank pump is best for fuel injection.

 

[mouserider]

a in-tank pump is best for fuel injection.

im already talking with aeromotive , to get their gen 2 tank with in-tank pump pre-build, but i want to try something quickly to confirm that the problem is indeed fuel delivery due to the wrong location of fuel pump, not something else.

P.S i will order the aeromotive tank anyway, in tank is still better in long run.
Edited: tank ordered, but im from Europe, it will take around 20 years to get here, so i still would like to test with my current pump.

 

[Don Frelier]

When I did mine I removed the sock on the sending unit as the pump should have a pre-filter.
I mounted it just in front of the rear wheel under the rear passenger seat.
Do you have a recirculation line with a regulator or is it direct to the EFI unit?

 

[R/T Boy 67]

If you use an external pump it needs to be as close to the tank as possible. With the stock pickup and fuel line setup, gravity feed is not really an option.

 

[mouserider]

When I did mine I removed the sock on the sending unit as the pump should have a pre-filter.
I mounted it just in front of the rear wheel under the rear passenger seat.
Do you have a recirculation line with a regulator or is it direct to the EFI unit?

sock is removed, oh, understood, but how did you run your lines?
yeah, i have a return system with regulator under the hood and return line from it back to the tank.
My car runs fine, but struggles on acceleration, fuel pressure goes erratic under load, jumping from 40 to 70psi, guys from holley said, thats an indication of insufficient fuel flow to the pump
Also AFR log shows huge AFR spikes, car goes crazy lean like 29 AFR.

 

[mouserider]

If you use an external pump it needs to be as close to the tank as possible. With the stock pickup and fuel line setup, gravity feed is not really an option.

exactly this, but where close? before the diff? just lower then sending unit, or lower than the tank? there is nothing lower than the tank back there.

 

[rmchrgr]

a in-tank pump is best for fuel injection.

X2. Unfortunately I don't know of any EFI-ready tanks for '71-up cars.

sock is removed, oh, understood, but how did you run your lines?
yeah, i have a return system with regulator under the hood and return line from it back to the tank.
My car runs fine, but struggles on acceleration, fuel pressure goes erratic under load, jumping from 40 to 70psi, guys from holley said, thats an indication of insufficient fuel flow to the pump
Also AFR log shows huge AFR spikes, car goes crazy lean like 29 AFR.

Before you start throwing money at a new fuel pump - you may have other issues. #1, AFAIK, the Sniper has an internal fuel pressure regulator so maybe ditch the external one you have and see if that helps. #2 - do you have a mechanical gauge in line just to be able to verify pressure at the throttle body?

Couple more questions -

Are you still running the initial "Wizard" tune or have you built custom fuel and ignition tables?

Have you verified your static timing?

Have you checked thoroughly for intake and exhaust leaks?

Have you run data logs and checked for RFI?

Have you joined the Holley forums and posted up your config file and data logs to see if anyone is willing to help?

Let us know so we can better pinpoint your problem.

 

[vance.dykes]

hear is 2 of them

Gen II Stealth Fuel Tank, '71-'72 Charger Road Runner

P/N 18162: Gen II Stealth Fuel Tank 71-72 Charger Road Runner With Stealth 200 pump OEM style tank, fully assembled. 20-Gallon Capacity. Fuel level sending unit 73-10 ohm. Complete with new tank, fuel pump, fuel sock. Phantom baffle assembly built-in. AN-06 O-ring Inlet/outlet ports in factory...

aeromotiveinc.com

Complete Fuel Injection-Ready Tank Kits

 

[R/T Boy 67]

Back to basics. Is the pump big enough and working properly? Is there any restriction in the suction line, such as plugged sock filter or pickup tube? Is the pickup tube too small? Is the tank vented properly? You want to have the suction height as short as you can,within reason. Suction height is the distance from the fuel level to the highest point in the suction side of the pump, including the fuel line. This height will change as the fuel level goes down. Holley should be able to tell you what is acceptable as far as height goes.

 

[rmchrgr]

hear is 2 of them

Gen II Stealth Fuel Tank, '71-'72 Charger Road Runner

P/N 18162: Gen II Stealth Fuel Tank 71-72 Charger Road Runner With Stealth 200 pump OEM style tank, fully assembled. 20-Gallon Capacity. Fuel level sending unit 73-10 ohm. Complete with new tank, fuel pump, fuel sock. Phantom baffle assembly built-in. AN-06 O-ring Inlet/outlet ports in factory...

aeromotiveinc.com

Complete Fuel Injection-Ready Tank Kits

Cool, good to see other companies stepping up for those cars.

 

[mouserider]

X2. Unfortunately I don't know of any EFI-ready tanks for '71-up cars.



Before you start throwing money at a new fuel pump - you may have other issues. #1, AFAIK, the Sniper has an internal fuel pressure regulator so maybe ditch the external one you have and see if that helps. #2 - do you have a mechanical gauge in line just to be able to verify pressure at the throttle body?

Couple more questions -

Are you still running the initial "Wizard" tune or have you built custom fuel and ignition tables?

Have you verified your static timing?

Have you checked thoroughly for intake and exhaust leaks?

Have you run data logs and checked for RFI?

Have you joined the Holley forums and posted up your config file and data logs to see if anyone is willing to help?

Let us know so we can better pinpoint your problem.

sniper 2x4 doesnt have a pressure regulator, so i have to run external one, which i do, mechanical fuel gauge is installed and i can watch it while driving and also i confirmed the gauge with another one, on the load both start to jump from 40 to 70, however should be steady 60.
Sniper setup is 100% correct, as i have been dealing with it for more than a year now, static timing is verified, no leaks, tables are okeish, so yeah, its definately fuel related problem

 

[mouserider]

Back to basics. Is the pump big enough and working properly? Is there any restriction in the suction line, such as plugged sock filter or pickup tube? Is the pickup tube too small? Is the tank vented properly? You want to have the suction height as short as you can,within reason. Suction height is the distance from the fuel level to the highest point in the suction side of the pump, including the fuel line. This height will change as the fuel level goes down. Holley should be able to tell you what is acceptable as far as height goes.

pump yes, big enough, confirmed by several sniper efi specialists, no restriction, tank was removedd, cleaned, new sender unit installed, sock filter removed, tank vented properly.
Basically i just want to understand where is a closest and lowest point for fuel pump test install .

 

[rmchrgr]

sniper 2x4 doesnt have a pressure regulator, so i have to run external one, which i do, mechanical fuel gauge is installed and i can watch it while driving and also i confirmed the gauge with another one, on the load both start to jump from 40 to 70, however should be steady 60.
Sniper setup is 100% correct, as i have been dealing with it for more than a year now, static timing is verified, no leaks, tables are okeish, so yeah, its definately fuel related problem

Gotcha. Didn't realize the 2 x 4 was not internally regulated.

It sounds like you might want to look into one of those EFI-ready tanks listed above. In-tank pumps really are the best solution for EFI. You're probably aware but since they are submerged, the pumps are quieter and run cooler. And unless you run the tank dry they will provide a constant and consistent amount of fuel. I have an in-tank pump in my Sniper-equipped Coronet, I've never had a fuel delivery issue.

 

[R/T Boy 67]

Well since you asked, the absolute best place to mount the pump is attached to the tube coming out of the tank. I'm sure that is not possible, so mount it somewhere on the frame that is roughly the same height or lower and keep the suction line close to the same height. I don't think it is that critical, to be honest with you, but there you have it.

 

[furious70]

Fwiw I've been running the same walbro 255 pump on the frame rail in front of the leaf spring. Efi since 2009, turbocharged since 2012.
You have to prime it with the hump up in the line but once you do since it is lower than the tank it's fine. Stock tank. Stock pickup. No sock. 100 micron pre filter OEM GM post filter.
Now, if I'm at 1/4 tank or lower and I get froggy I do uncover the pickup

 

[64fury74charger]

I put an Aeromotive efi tank in my 74 Charger along with sniper system. The 10 micron filter is riget next to the tank. When the original Aeromotive pump died I was able to mount an external pump with the filter until I got the replacement installed.