Having trouble with my 94 Z28. Nothing wrong with the starter, but it turns over for a while before the engine fires......Please help!

 

I'd hook a pressure gauge up to the shrader valve on the back of the fuel rail then turn the key to "on" without starting it and see if the pressure holds at about 40 psi or if it quickly drops off.

 

yes it does hold at 40...im stumped

 

Does it have any other problems besides prolonged cranking time?

 

next time you try to start it, turn the key on for 5 seconds and then off without starting it. do this 5 or 6 times. Then finally try to crank it over. If it starts fine then without cranking for a long time, the pump check valve is bad and would require a new pump to eliminate the problem.

 

That's what I was thinking until he said it holds pressure. Unless his is a slow pressure drop. Mine would drop completely in just a couple mins.

 

Don, do you have stock injectors, you link said Hypertech Perf Chip, have you ever had it tuned. If your fuel rail is at 40 # when you start to crank then that rules out fuel supply. However there are some PCM engine starting tables that rarely need to be changed unless you are having problems, they control timing, injector prime pulse, extended crank injector pules, etc. Do you have to hold the throttle open to get it starter (leaking injectors) You also have some MSD, Bosh ignition mods listed, can you pinpoint when the problem started up. Was it after any mods. ?

 

If you think it's the injectors then pop the rail out and put a rag under the injectors and prime the pump. If any are leaking you should visibly be able to see it. If not then a fuel pressure drop could only be through the regulator or back through the pump. Prime the pump again and clamp the feed line. If pressure still drops then it's the regulator. This is also assuming you have looked over all the other lines and connections for a visible leak or looked under the car for gas dripping out.

Also, from shbox, "any indication of fuel in the vacuum line to the regulator, means the regulator is leaking and should be replaced. Check the line for fuel or the smell of fuel."

That should cover the pressure part of the discussion.

For reference - http://shbox.com/1/4th_gen_tech2.htm...essure_testing

 

Also, wondering if the car has any codes or other driveability problems?

 

no codes and the car run's fine once started.....When testing the fuel pressure, sometimes when I turn the key it goes right to 40 PSI, but sometimes the first time i turn the key it may only go to 10 PSI or 20 PSI and then every time i turn they key on after that it goes to 40 PSI. Also when it goes up to 40 PSI, over the next 2 minutes the pressure bleeds off slowly, is that normal?

 

did you try this

the problem with it not going to 40 when you first turn the key could be something different, but the pressure dropping off could be the pumps check valve

i am recommending this because if the check valve is bad and the pump needs to be replaced you might want to do that and see if it takes care of your intermittent lack of pressure on start up