Hi guys, I've recently been trying to track down a problem with my lt1 that started a month or so ago. I was driving and the car just died. After cranking multiple times, I had a big backfire and the car died.

I also had a water pump leak, so this week I replaced the opti and installed an electric water pump. The car started up ok but while I was refilling the radiator, it just died. I also noticed that if I revved it, it had the tendency to pop, but I'm thinking that is just because it was running cold.

Anyways, I hooked up a fuel pressure guage to the schrader valve and with the key turned forward, the fp would read from 18-28psi. When I turned the car on with the vacuum line to the regulator unnatached, the guage read ~30-35psi. Anyway, can the car run at the fuel pressure, or is it possible that the fp guage I have is faulty (you can never trust Chinese made tools). Are there any other diagnostics that I can do or should I go straight to the fuel pump?

 

It can run at those pressures, however it should be running pretty lean and the PCM should be compensating by holding the injectors open longer. Since stock should be around 43-46 with vac line disconnect and about 8 or so less connected, your regulator may be boogered, your gauge may be faulty or your pump may not be working properly.

First thing I'd do is take it to a shop and have them measure your pressure with their gauge and then go from there. At 50-80 bucks/hr I'd think that a min and max charge would be no more than 25-40 bucks to have it checked out----worth it in my opinion.

 

I've been doing some searching on the forums and I've been reading people talking about pinching the return line to the gas tank and checking the fuel pressure to help rule out the FPR.

Does anyone have any more information on this or a more detailed explanation on where to disconnect and pinch the return line?

 

You don't disconnect the line.... just pinch down on it to prevent fuel from returning to the tank. But given the fact the lines are a fairly rigid plastic tubing, "pinching" one closed may damage it.

 

Is there a better way to do it without potentially causing damage to the fuel lines?

 

The most common failure of the FPR is the diaphragm. Have you pulled the vacuum compensation line off, and looked for wet fuel in the line?

 

Yup, pulled the vacuum line off and didn't see any fuel coming out of the fpr. Is it safe to assume that it is the fuel pump? Sometimes it will crank and run at proper fuel pressure, but then it will die and there will only be about 10-20psi in the fuel system.

The part that baffles me is when fuel pressure goes down that low, if I put a spark plug tester between a plug and wire, I don't see any spark

I'm so lost please help.