Cascade Crew

[Quasi-Traction]

a friend of mine is having some fuel trouble with his 1997 GMC Jimmy.

its a Vortec 4.3 V6 with TBI. I haven't had much time to look at it but he's replaced the fuel pump relay so far and still has the same problem. it will crank and crank, but not fire. He says if he squirts carb cleaner down the TBI unit, it will fire, run for a sec and then die. He seems pretty certain that its a fuel problem. I tried listening while he put the key in "run" position, and i don't hear the pump priming at all.

Would TBI just have the in-tank pump, or an in-line pump as well?

I figured the first place to start was by checking fuel pressure. I found the shrader valve location, but what is the spec for proper fuel pressure?

In case he's wrong, what else should I check? this is my first real time tracing a problem on a TBI system, so any help or tips on where to start are most appreciated.

[chevymad]

Sounds like this is a vortec and not a tbi system. Vortecs have a schrader. and are actually port injected inside the intake. Vortec's require 60psi to start but run at 55. Sometimes you can start one with a bad pump by jump starting(increases voltage to pump) then it will run ok.

There are poppit valves instead of actual injectors. Each poppit valve has a spring in it that requires that much pressure to overcome and squirt fuel.

[Quasi-Traction]

That makes sense. It did have a shrader, but the fuel lines seemed to plumb directly into the intake, and had a throttle body that was mounted vertically. I just assumed it was TBI.

Either way, I just spent the last 4 hours or so dropping the tank with him and replacing the in-tank pump.

Car fired, and seemed to run okay when he took it around the block. Took No SES light, nothing.

[Xophertony]

nice work chris.