I have a 96 Formula, I took out the LT1 and replaced it with a GenI sbc. my question is about the fuel pump, I am using the stock pump in the tank. when you turn the key on the pump primes and sounds like it shuts off. does it and what makes it turn back on. my car only starts for about 10-15 seconds and then shut off if I dont give it some gas. I dont have a fuel pressure guage on it yet, to tell if it has fuel or not. any info on this will be greatly appriciated. thanks

 

Maybe you could just wire the fuel pump up to a switch so when you turn the switch on the fuel pump turns on..whats your idle set at?

 

You may want to connect the relay trigger to a switched power source, so that when you turn the key ON, the pump will stay on. Normally the computer is what triggers the f/p relay. It won't allow the relay to stay energized unless it sees pulses from the opti (which you probably no longer have).
It might be possible to overcome the need for the opti pulses with some custom tuning, but I am not sure what might need to be done.

A quick and dirty way to make it work right now would be to loop a switch to the fuel pump prime connector.

 

GEN I!!! if it's carbed you need to regulate that pressure or you'll seriously mess your carb up it can't take 50 psi!!!!! it needs about 4-7 psi!!!!! just fyi

i would assume since "my car only starts for about 10-15 seconds and then shut off if I dont give it some gas." you have plenty of gas, and are flooding the motor, hitting the gas pedal opens a butterfly that allows more air in which will lean out a rich mixture and keep it running,

unless... you're pumping to keep the accelerator pump squirting in order to keep it alive like a chokeless setup, in which case you have like, no gas at all....

either way what's the setup? how much of the computer is being used? all that juicy info might help more, it could be something in the computer since your gen I wont have 1/4 of the sensors that your computer expects data from

 

I have a regulator on it and I just got a guage now to monitor it. Im not using hardly any of the wiring harness for the engine. I just wasnt sure if you could directly wire the fuel pump to the ignition or not. I only have to hit the throttle to squirt gas in the carb to keep it running. but I run out of gas.
shoebox, where would I find the fuel pump prime connector at? I think I might just try that, cause before summer gets here im gonna drop the tank and plumb in a new fuel system. I am just trying to get this working now to be able to move the car on its own. thanks for all the help

 

It's near the computer. You can jumper 12v to the connector for a test to see if this will work for you. The pump should run as long as you have it jumpered.

 

ok sweet! so I just run a keyed hot wire to that wire and it will turn on when I have the key on and stay on untill I turn the key off? thanks

 

That should work. For something permanent, I personally would prefer to use a switched 12v source to operate the existing f/p relay. You would use that switched source to connect to the wire at the relay what would normally come from the computer.

 

You don't want to run the fuel pump long-term off the prime connector..... that bypasses the relay, meaning the full current draw for the fuel pump is through the skimpy prime connector wire. You want to connect switched power to the wire that used to attach to pin A7 on the PCM. That operates the pump through the relay, as Shoebox indicates.

 

kinda old thread but im doing an ls1 swap into my 94, and for some reason the fuel pump doesnt prime, or power up period. now in the ls1 and lt1 computer it has a fuel pump realy controal, i made sure those are in the correct spots...out of the ls1 harness into the c-220 "J" in the lt1 car....

my question i guess is where does the fuel pump ground at? is it the c-210 "B" ( i used a wire in the ls1 harenss thats called "fuel ground/sensor return" its the ground for the fuel level sensor, so it shouold ground out the pump

and this fuel pump relay control, does that stay hot all the time and prime the pump? or does it only prime?
the car doesnt prime or stay on (havent tried to start it yet, no motor)

and will any of this cause a problem with a walbro hotwire kit? i did hook it up to power when testing.

 

bumo for tonite so i can fix it!
injuneer, shoebox?