ok, so my fuel pump went bad in my 87 Iroc, 5.0 TPI, and i went to autozone and bought a new on. Did the whole drop the axle and exhaust and tank and pain in the A$$ and so on and so on, new fuel pump in...only 30 PSI of feul pressure. *Sigh* pulled feul in line by the wiper washer reservoir, feul comign through no problem, nto as much as id like, but coming through, pulled the return line and got nothing, so i switched the feul pressure regulator, stil only 30 PSI. so im gunna bump it up to a pump capable of like 100+PSI, whats the best bang for my buck?

 

did you make sure the rubber line in the tank wasnt busted thats why your losing pressure?

 

it was busted, i replaced it.

 

so are you getting the right pressure now?

 

no, im only making 30 PSI while the pump is on, then when i shut the car off it dosnt hold pressure, it drops to 10 PSI

 

replaced auto zone pump with Walbro pump, still not making any pressure. also, the pump continuously primes, why would it do that?

 

It should only prime when you turn the key to on for about 2-3 seconds (If needed). I had to get my pump replaced a while back from the stock one, but it only primes for about 2-3 seconds when key is turned to on and when the car shuts off.

 

i know its only supposed to prime for a moment, any idea why it would prime constantly?

 

Is it possible you have a leaking injector? My key on fuel psi is 40. At idle it drops low to mid 30's, under a load is 40psi. I have the stock regulator. Hope the info helps.

 

i dont think that its getting enough pressure to the injectors to make it fire, the car wont start.

 

check the regulator and look at the vac line coming from the reg and see if
it is leaking.

 

The prime is controlled by the ECM because it supplies the power to the fuel pump relay coil.
If the relay contacts are fusing together when the ECM energies the relay, the pump will stay on even after the ECM de-energies the relay coil. but if that is true then the contacts must disconnect when the ignition is turn off, if not the pump would continue to run because the fuel pump is powered from an always hot fuse.

You really should fix the prime problem first.

The fuel pump has a check valve as long as it works pressure should build up between it and the regulator. for now I would not suspect the check valve (new pump.)
The pressure is being lost after the pump, or flow is restricted before the pump. Contmination from an old filter sock can make a new pump go bad - you did change the filter sock?
Some replacement pumps come with hose clamps and a short piece of hose to eliminate the pulsator, but as long as you install the pump properly you don't need them.
Since you haven't mentioned any fuel leaks the problem is mostl likely in the fuel tank.

 

30 PSI should be enough to start the car. Maybe try changing over the relays as I think there are 2 the same ones next to each other. Maybe the fuel pump relay is toast.

 

i did replace the fuel pump screen. i dont have any leaks, and the vac line from the regulator is fine. i will check on the priming issue tommorow, however i know ficing this wont get the car to start. I am leaning towards there being a restriction in the lines somewhere, and moreso between the feul filter and the fuel rails, im gunna have to tear it all apart to find out. if there is no restriction, and i fix the priming issue, and the car still wont start, then i have no idea what to do.

 

So the car cranks over, you have 30psi fuel pressure and it will not fire up?

In that case you might want to check if you have spark. Like I said 30psi shoudl start the car. In the GM service manual I think it says anything under 24psi and the car will not be driveable. So if you have 30 it should not be an issue starting the car. Have you tried pressing in the schrader valve to see if you have fuel coming out under pressure?

 

Why would you want 100+ psi? Our cars are 42 psi stock. LS1 ones are in the 70-ish range (I forget exacly what...I don't have on or wanna do the searching for the #), but 100+ psi isWAY too much anyways.

 

i have spark, i know this, it is definatly a feul issue, i have feul coming through the feul in line, but not coming through the feul return line.