Hi,
Having issues with my 1994 z28 when starting. It turns over for 5 or so seconds before starting. Sometimes takes a few tries. Usually worse after setting for hour or more.

I have check fuel pressure. When running at idle it is about 40 psi. When I pull of vacuum hose to FPR, it increases to 43 or so. I do not see or smell gas in vacuum line.

My first question is, with engine off should fule pressure stay at 40? When I shut off engine, pressure drops within 1 minute to zero. If I turn key and let fuel pump pressurize, it goes back to 40, but drops after pump stops. Is this how it shopuld work? I have no idea if fuel pump has check valve or if there is a check valve somewhere else.

Any help or guidence would be very much appreciated.

 

it should hold pressure at about 36 and some drain down after a few hours. your fuel pressure regulator or the fuel pump check valve is failing. need to test fpr check number 33 on the list here http://shbox.com/1/how_tos.html

 

Thanks for the exremely fast response, it is much appreciated. I figured it should hold pressure, now on to see if pump or fpr. Please be the FPR!

 

You can do a quick by turning the key ON & OFF several times to prime the fuel system before attempting to start. If after cyclyng the key the engine starts right up, it is a good sign that the FI system is not holding pressure as it should. It could be a bad fuel pump check valve, bad regulator, or one or more injectors leaking.

 

So to rule out the fuel pump, can I just hook up a pressure guage at the fuel filter. I would dissonnect on end of filter and hook it to the pressure guage. That would take the rest of the system out of the equation.

I do not have fittings to quick connect at fuel rail to check. I think I have what I need for fittings at the filter.

Any thoughts? Also, any ideas where to get quick conect fittings to plug in a fuel rail?

Thanks

 

That is not the place to connect the pressure gauge. It has to be connected at the shrader valve on the fuel rail. There is a sticky in the LT1 section on how to properly check the fuel pump and pressure regulator.
https://camaroforums.com/forum/lt1-l...86/#post171748

 

Thanks, I already checked pressure at shrader valve and it did not hold pressure. I wanted to isolate my check to only the fuel pump. I did not want to clamp of an 18 year old return fuel line.

I bought a quick disconnect fuel line fitting for the return line. Added a small section of fuel line and clamped off.

I then retested pressure and after cycling the pump a few times it held steady. Changed the fuel pressure regulator. Rechecked pressure and it held steady with car off. Ran car around a few times with no issue.

Later that day, same problem. re-cked fuel pressure, and it drops off rapisly after cycling the pump. I assume that the shut off valve at the fuel pump is intermittent.

Is a intermittent shutoff a common problem?

Thanks

 

i went through three adjustable holley fpr s. holley called and asked for the model and production numbers. i have a ptis fpr now. works great.