The Untouchables

ok so im working on a 96 blazer with a 4.3l vortec engine with the spider type injection system , the truck has a new fuel pump , new fuel filter, it was running great but had a slight hesitation when u gave it the go pedal.

now it wont start ,it not gettting any fuel into the cylinders,
it will turn over fine has spark but no fuel, cause if u pour some gas in the throttle body it will fire right up untill it burns that fuel , is there any way to test this injection system , im going to hook up my scanner to it and see if there is any codes stored in the ecm,

this truck is driving me nutz im trying to sell it and now its giving me this problem.

one thing might be part of the problem is that the fuel pressure is only 10 psi so im not sure if maybe the fpr is stuck and returning all the fuel pressure back to the tank it will hold 10 psi but thats it .

im at a loss with this thing can any one help,

i also swapped out the crank position sensor to see if that was the issue but i dont thing thats it, is there any other sensor on this engine that could be bad thats telling the injectors not to fire? or could it be my fuel pressure causing the problem?

any help would be great on helping me with this truck,

now those wires that go into the intake do those goto the spider and tell it which cylinders to fire on? is there a way to see if they are with a DVM or test light?

The Untouchables

so i scaned it no codes stored all sensors check out, still no crank , nobody?

MDTAHOE

10 psi is not nearly enough for any fuel injected motor to run unless it is TBI. How do you know it is not getting ANY fuel to the cylinders. It will NOT run at all on 10 psi. If it is truly not getting fuel in cylinders then it is probably because they are poppet style injectors and the will not work properly with out pressure.

The Untouchables

yes it is the poppet style injection or "CSEFI" is called i got it narrowed down to a defective fuel pump, the pump still works but must have some kind of internal leak that is causing it to not build fuel pressure.

at first i thought it could of been a stuck fuel pressure regulator but now after messing with it im shooting toward a defective new fuel pump.

tm4hammer

YA it sounds like you got a bad pump i think you need at least 58 to 60 pounds fuel press. to start it, then after its running and if the if the reg is working it should drop around 3 psi, so around 60 to start and 58 when running i have bought many a crap pump and had do the job twice i only use bosh now made all the differance and keeps the time and money in my pocket where it belongs to bad labor isnt included in these junk pump warranty's

The Untouchables

ok i got the fuel pressure problem fixed , now im dealing with a bogging problem, if u ease on the go pedal its fine but any quick movment and it act like it just lost fuel.

tm4hammer

whats your pressures and drops

The Untouchables

60psi at prime .pressure is 57 psi at idle 3k rpm 56psi but goes back up to 57 psi,

i think i got a bad map sensor