86IROC57L98

I've got an 86 iroc with a swapped carbed 350. It runs good, but i noticed that my fuel pump is always on whenever the key is in the on position. i have a fuel pressure regulator on it set at 4 psi, but abuddy of mine told me that it could have a shut off valve so it knows not to overflow the bowls in the carb. is this true, should it have like a shutoff valve or something? im not to intelligent on these types of subjects. Someone suggested that i put a switch in so i can shut it off at different times. all help is appreciated! thank you

91interceptorZ

iTrader: (3)

Is it a factory carb. car, or did you put a carb on a fuel injection car?? is it overflowing bowls?? does car have a factory fuel return line?? what kind of fuel pump??

86IROC57L98

my car was originally fuel injected (not sure of TBI or TPI) but it has an edelbrock 1406 600 cfm on it, with a puralator fuel pump (not sure of the GPH or PSI it does) and ive not seen a return line and would like to know more on that subject. i dont think the pump is hooked to a relay, just that the pump runs as long as the key is in "ON" position or running.

Iroc-Dennis

if your car is before a tpi than you must have a return fuel regulator!

that means, a regulator with a return line for the pump!
i doing the swap and tested the fuel presure!

i using the mallory 4309 return style regulator!
i set my psi on 5 PSI for the holley double pumper
its not overflowing because the return regulator.

it is right that the fuel pump is on wen key is on
the fuel pumpted all the time around and the carb take the fuel he need!
the rest of the fuel go`s back to the tank because using a return regulator!

thats the way it must work for you!

but only if you using the original or aftermarket electric fuel pump

Dennis

Rolling Thunder

No you dont need a shut off valve. The way a regulator works is it restricts fuel flow to maintain a certain pressure. If the pressure builds up higher and higher eventually in theory the regulator will close off the outlet entirely so no more fuel can go through. This is where a problem comes in. If you have no return line and the regulator closes the fuel has no where to go. The fuel pump will continue to try anyways and will be overloaded. This will cause the pump to burn out prematurely.

86IROC57L98

that sounds about right, but im not sure if i have a return line, and if so it wouldnt be hooked up that i know of. i know the main line comes into the engine bay, hooks up to a hose, runs through a fuel filter, then through the regulator and to the carb. Unless the other return line is further towards the tank than the engine bay, where would it start to branch off?

Rolling Thunder

It should branch at the regulator itself

86IROC57L98

would that be a fuel pressure regulator with a third nozzle or like a tee fitting right before it? cuz mine only has the 2 for fuel in and fuel out with a dial **** that you push in and turn anywhere from 1 - 5psi

Iroc-Dennis

you need the return style regulator

Mallory 4309-----------> Search this!!!

86IROC57L98

is there a way i can substitue for a week till i can get one of those regulators?

Rolling Thunder

In theory you could temporarily make a T before the regulator. However this isnt really a good solution as the t would hove to be the right size to allow a controlled bleed off of pressure while not being so much that it causes a pressure drop at the carb. Not really a good solution but i understand when a car is your daily driver things have to be done that are not ideal.