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Roll your own FI pump setup?

R

RV7ForMe

Well Known Member
Patron
Hey guys,

for those of us on a budget. I understand that the pumps widely used by the EFI people here are Walbro GSL393.

There are plenty of options for Pre and Post filters like Holy and summit.

But I am wondering what the pump bypass would have to be and were to get it? Check valve? something with a really light pressure to open?

Also I saw that the some EFI setup uses dual pumps without a bypass. Is that setup safe to use with normal AFP injection? Would that still work if you shut down both pumps? or is this just on the efi since it wont spin the prop without high pressure anyway so if both go out you essentially no longer need a bypass.

Thanks :)
 
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I built my own dual pump setup, not sure I would associate the word "budget" with this as the parts are not cheap. I have a pair of GSL393 pumps with Earl's 35-micron filters on the inlets and Russell Check Valves on the outlet side. Both pumps feed an Aeromotive Universal Bypass pressure regulator set to 43 psi, excess fuel is returned to the tank. There is a Fuelab 848 10-micron filter on the firewall that feeds the injectors. The Earl's and Fuelab filters have replaceable filter elements. There are also a fuel tank shut-off valve and a fuel return isolation valve that allow the entire pump assembly to be removed for service without draining the fuel tank. It is wired for Pump A only or Pump B only operation. The parts came from Summit Racing.

Not sure I would run the pumps without a bypass, these pumps need fuel flow even when the engine is not running to keep them cool.

RV12 N895HS Fuel Pump Module 20260330.jpg
 
The EFI systems available for EAB, SDS and EFII, bypass excess pump capacity back to the fuel tank in use through a bypass pressure regulator generally mounted firewall forward.

Pressure-regulated fuel is plumbed from the regulator to the injectors and excess fuel is plumbed from the regulator back to the fuel tank in use.

A dual fuel valve is used in the cockpit so that pump inlet fuel and regulator return fuel are from the same tank.

Pumps like GSL393 have a built-in check valve to prevent backflow (ref SDS website “Pumps have internal check valves to permit single pump operation.”). I imagine any automotive EFI fuel pump has in integral check valve in order to hold system pressure after shut-down to prevent fuel boiling in the hot start scenario.

SDS uses a Borla pressure regulator and EFII uses an Aeromotive pressure regulator (“Aero” is meant to imply aerospace standards but market is automotive race and hot rodding).
 
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Thanks for the input. I see you both are running a High pressure system with return lines.

I will be running mechanical Fuel injection. So I need the pump for Take off and landing only but the GLS393 is like 100-130$ vs the 700-1400$ setups you can bus from the usual places.

Something like this?
 
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Airflow Performance sells an “Auxiliary Pump Assembly” which uses an automotive fuel pump and incorporates a “Relief Bypass Valve Assy” that bypasses excess fuel pump capacity back to the pump inlet versus back to the fuel tank.

Pump is currently Delphi FD0011. Was formerly Airtex E2315.
 
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RV7ForMe said:
Thanks for the input. I see you both are running a High pressure system with return lines.

I will be running mechanical Fuel injection. So I need the pump for Take off and landing only but the GLS393 is like 100-130$ vs the 700-1400$ setups you can bus from the usual places.

Something like this?
Click to expand...
The AFP setup is only $500 something.. not 700+.. Then again, you’ll still need filters..
 
Items for fuel systems can be purchased on Jegs and Summit for a lot cheaper. Most of them have mounting brackets as well that you can fit to your mounting needs. The filters go down to 10 microns and you can take apart and clean. AFP has good stuff but you can piece together a system if you are willing, for less money overall and still achieve the same results.
 
johnbright said:
Airflow Performance sells an “Auxiliary Pump Assembly” which uses an automotive fuel pump and incorporates a “Relief Bypass Valve Assy” that bypasses excess fuel pump capacity back to the pump inlet versus back to the fuel tank. Pump is Airtex E2315.
Click to expand...
Used to be. They were discontinued. Replacement is similar but longer, so requires mods.
 
I like the general layout and equipment of the system pictured above, but I would point out that while the return line can be tapped off anywhere, here basically right at the pumps, if tapped off just prior to the fuel injection or carburetor, then it also serves to circulate cool fuel through the entire fuel system. Requires longer return lines though.
 
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