poposhad

I have 94 z28 and I was wondering if you can give me advice on this issue. The car would stop running after running for a bit, after a while it would restart and sometimes it wouldn't. I have replaced the fuel filter and the ignition module. You could hear the pump prime after turning ignition. During the time it failed to restart, I disconnected fuel line at the fuel rail and no gas was being pumped. I disconnected the the filter and had the ignition on and the fuel would get pumped out. I notice a kink in the fuel line from tank to filter so I'm trying to find part number for that line. Strange that it works sometimes though. No error codes except air pump since I removed it. Any suggestions or guidance would be appreciated , thanks

Injuneer

How old is the fuel pump? Have you checked the pressure at the rail? When it won't start, is there any fuel at the Schrader valve?

The pump only primes for 2 seconds, then shuts down until the PCM gets the cam position signal from the Opti, indicating the engine is trying to start.

Try testing fuel pressure, and starting it using the pump prime connector near the PCM to run the pump.

poposhad

The fuel pump is less than a year old. When the engine would stop after running for a few minutes, i disconnected the fuel line from the rail and cranked the engine, no fuel came out. I disconnected the filter line and turned it over and fuel came out. where is the prime pump connector located and do i just provide 12 volts to it to keep it running. Also, the fuel line from the tank to the filter has a kink, I would like to replace it, would you happen to know the part number, i have looked but couldn't find it. I don't think the kink is the cause but I would prefer to replace it. I am assuming that if it keeps running with the pump manually manipulated that it could be the Opti going bad. Thanks

Injuneer

If it was a cheap replacement pump it could be on its way out. Even if it's a Walbro, there are lots of cheap Chinese counterfeits being sold.

I read your original post, and understand what you did disconnecting lines. No need to repeat it. But that's no substitute for checking the fuel pressure. Which line did you disconnect from the rail - the one to the passenger side hard line, or the one to the pressure regulator on the driver side?

The prime connector is for testing the pump, not a way to solve the problem. Shoebox has the location:

http://shbox.com/1/fuel_pump_prime.jpg

The prime connector bypasses the security interlock and the fuel pump relay. Wire from the battery + terminal, with a 20 amp inline fuse.

Took a quick look at a couple of GM parts dealers parts diagrams and couldn't find the line from the sending unit to the filter. I have access to a download for the 4th parts diagrams, but it's a bit on the large side for my iPad, so I have to wait until I'm on my desktop.

poposhad

I disconnected the driver side, used a tool that fits over the tubing and it releases the lock. It feeds the rail from the driver's side. Ok will get a pressure gauge to check pressure. Thank you for your help

Injuneer

The line that connects to the fuel pressure regulator on the end of the driver side rail is the return line, not the supply line. If fuel pressure is below ~40 PSI (no vacuum), there will be no flow out of the regulator. The regulator closes off return flow to control the pressure.

poposhad

Thank you will check , appreciate it