Fuel Pump question

[wayne69]

I am in the process of fabbing up my own gas tank and running a walbro in tank pump to the carb with later plans of upgrade to EFI with the same pump, is this a good idea?

[camcojb]

I am in the process of fabbing up my own gas tank and running a walbro in tank pump to the carb with later plans of upgrade to EFI with the same pump, is this a good idea?

good idea but will probably need a different regulator for carb vs efi.

Jody

[68Formula]

Remember for pump flow as pressure increases, flow (from the pump) decreases. So the same pump becomes effectively smaller going from carbureted to EFI.

Q2=Q1 x SQRT (P1/P2) where Q1 is flow rate at pressure P1 and P2 is desired working pressure.

Youre going to be returning a lot of fuel back to the tank to get a pump that will work with EFI to run a carburetor.

[wayne69]

Do you think it would be a good idea to install a carb pump first and then upgrade to an efi pump when I do the conversion?

[68Formula]

You could:

1) Like you said, install a carb pump first, and the EFI later. (Probably the best option).

2) Install the EFI pump, but keep it disconnected and run either a mechanical or electrical external carb pump.

3) Install the EFI pump and build a circuit to limit the pump voltage to 7 volts under all conditions (this will slow the pump making it flow less). I'm not really sure if this will still limit it enough to allow it to work with at carb pressures.

TBI is usually double or more pressure than carb and Multipoint is typically 5 to 6x carb pressure (assuming no boost).

[Doug F]

We've run walbro pumps with a carb (with a return and a 6 PSI regulator) at work and haven't had any problems. Can't say we've put 50k miles on it in 95F weather, but it works.

[camcojb]

3) Install the EFI pump and build a circuit to limit the pump voltage to 7 volts under all conditions (this will slow the pump making it flow less). I'm not really sure if this will still limit it enough to allow it to work with at carb pressures.



realize some efi pumps will fail prematurely if they get lowered voltage. On some the way to slow them down is to pulse the voltage with a controller, but not lower voltage. Still think you'll need a specific regulator to get the pressure down. Aeromotive makes one but it's about $190 and you'd have to replace it when you went to EFI later. Might be cheaper to go a different pump.



Jody

[wayne69]

Thanks Guys! I think I am going to go with chioce #2 and use a mechanical pump for now. This is a really awsom forum I really appreciate all the help.

[wayne69]

While I am at it does anyone have measurements of an in-tank walbro fuel pump. I need them for my in-tank fuel mount.

[Footjoy]

Wayne69

Can you take pics of how you are doing this and pm me.

Thanks

Greg