My moms 89 has a L03 tbi, when driving it drives ok, but it dies every now and then.

We bought it and had no fuel pressure but it still ran, upon removing the carpet in the hatch area, theres a plate with bolts and silicone, under was the gas tank. We looked at the pump and the hose they used in the tank was being dissolved by gas, so we replaced it with proper gas hose.

Still no pressure when we hook up a tester, but steady streams come out of the tbi, whats up with that?

 

TBI fuel pressure is 9 to 13 psi. Need to check it on the larger of the two lines to the TBI. It will be the feed line on the driver side of the TBI unit. Easier to check it at the frame to engine hose.

If the pressure is less then 9 psi, it may be a bad fuel pump, or the FPR spring is broken. Can pinch the return hose to see if pressure builds. If not, FP, if so, the FPR spring.

RBob.

 

You seem to know a bit about tbi lol. What does the FPR spring do? where is it located? And on a pressure test, i get nothing on the gauge, but the car runs.

 

The FPR spring is part of the FPR, it sets the fuel pressure. It is located at the top rear of the TBI unit, in the can that hangs down from the injector pod.

Getting nothing on the gauge and having the car run isn't really all that unusual. The gauge could be bad, or it is a high pressure gauge that won't register that low (1 - 2 psi is enough to have the engine run).

Did you try pinching the return line?

RBob.

 

Its a fuel pressure tester gauge from auto zone lol, and i
ll try pinching the return line, haven't thought of that. Thanks.

 

Oh forgot to mention, spring is good, we rebuilt the tbi unit with new gaskets and rubbers, and the car was doing this before we rebuilt it so you know lol