fuel pump plumbing, press reg back to fuel pump inlet? Options

[jimkelly]

I have what we think is a fuel pump from a vw bus - it has one inlet (suction side) and one outlet (pressurized side). Can I run a fuel line from the pressure regulator back to the inlet side of my fuel pump - instead - of running tit all the way back to the fuel pump.

I have to take another look but I am not certain my car as a fuel return line in it going back to the fuel tank - is why I am asking.

Jim

[mihai914]

On those style of pumps, the return goes directly to the gas tank not to a fuel pump port. Although I never tried what you want to do, my first impression is no since the factory would of done it that way to save costs. Plus if the system is closed like the one you describe, it's like having a sink with no sewer, the fuel will have nowhere to go so fuel pressure will be sky high. The car will run but very rich.

[jimkelly]

I agree with you about the fuel having no place to go - I think it really needs to go into an empty space with no resistence - like the fuel tank.

I asked because I was told that if you put a finger over an orginal 914 fuel pump's fuel outlet nipple that fuel will come out of the fuel return inlet nipple of the fuel pump if fuel is feed to the fuel inlet nipple?? If this is true - the fuel return nipple and the fuel inlet nipple are connected inside the pump?

Regardless - I still feel going back to the tank is neccessary.

Thanks,

Jim

[aveale]

it has to pump the right pressure range (i think 35-50lbs).

what you do is not make it a closed circuit.

In from tank, out to jets, back to tank. Pretty easy (guess how I know about this.....)

T

[mihai914]

The original 70-74 pumps had three nipples, one suction, one feed and a return, and of course it had the Y fitting and the bypass valve in case of everpressure. The one you are thinking of adapting is a different design, I ran a 944 turbo pump on the 914 and eventually got a kink in the line, ther result is real high pressure.

You need to have a fuel pump that will give you the minimum volume and pressure as a stock one. The main function of a fuel pump is volume (liters/hour). If the stock pump is designed to go up to 55 PSI and you put one that goes to 100, there is no problem with using it because the pressure regulator is what determinates the fuel pressure in the system. But if the pump can't push the needed amount of fuel then it won't be to good when the engine revs.

Something that you didn't mention is if you have carbs or FI, in the first situation you can't even use a FI pump anyways, if you will run FI then the return line is a must. The car will run if the return is blocked and it will sound actually pretty good but at over 60 psi of pressure you're just looking for an engine fire.