Howdy all,

Need help with my sons 95’ Z28 5.7L. The other day he went out to start it and, no joy. It has lights and power and cranks well, just wont lite off and he even tried to jump start from another car, still no joy. Had it towed home and I looked underneath to check out the distrib & wires when I found the #7 plug wire melted in half. After replacing just that wire with a new one and thinking this would be an easy fix, still no start. After the wire replacement I noticed that it kind of diesels after the key is turned off, not sure if the timing is out or what. Is it possible that when the plug wire separated that it shorted out something. For all I know it could have broke awhile ago and he was driving around on 7 cylinders then something else gave in. Any ideas out there.

Thanks in advance

Don

 

hmm, it should start even if it was runing on 7 cylinders. Well you go back to the basics and see if it has the 3 things required to run, the correct fuel pressure, spark and air. Pull some plug wires and see how the spark looks, put a fuel pressure gauge on the fuel rail and see what that looks like... take that info and go from there...

 

I agree, it should start and run on 7. Did you look at the other 7 and see if you have a couple more fried ones?

 

If it has alot of miles proably time for a new opti..

 

Thanks,

Unfortunately, I haven't had a lot of time to devote to the troubleshooting of this. I did put a gage on the fuel rail shrader valve today, and with just the key on and even cranking it, I had no pressure registering. With the key on, I can hear the pump running, so I guess i'll check out the filter next along with checking for spark too.

 

If you can hear the pump priming, you at least know you have power to the fuel pump and that knocks off the idea of it being an electrical fault. Clogged fuel filters can cause problems, but if that doesn't fix the problem, I would look at the pump being at fault.

 

Well, changed the filter, and still no pressure off the fuel rail. The rail is getting a small amout of fuel which bleeds off when I hook up the gage hose but wont register a single psi even when cranking the engine over. I did verify the gage on my truck so I know it works.

 

well looks like you found the problem, now you get to deal with the fuel pump, haha

 

Well hell,

Changed the filter, pump relay, and just finished changing the pump, still no pressure to the rail or starts. Pumps does prime for the couple of seconds its suppose to, did the puel pump prime step and the pump does stay running but no pressure on the gage. Verified gage again on my truck, works great. Of course there's always the possibility that I installed a bad pump, but I don't want to beleive that yet, and yes, it was a autozone $179 one, but still. Any ideas left out there.

 

Shoebox's site is full of useful tools, including a procedure to diagnose fuel pressure issues: http://shbox.com/1/4th_gen_tech2.htm...essure_testing

 

Been there, done that...thanks

 

If you have a multimeter, it might not hurt to check the fuel pump harness connector and see what the voltage reading is going to the pump and make sure it is up to spec.

 

If you've been there and done that then have your ruled out a faulty fuel pressure regulator and/or leaky fuel injectors?

 

After debating long and hard about why I'm still not getting a reading off the shrader valve, I decided to pull the core out of it and try the gage again and guess what.....40psi with a turn of the key. I also before that disconnected the fuel line after the filter with the thought for a possible blockage, but plenty of fuel came out when disconnected so I put it back together and tried the shrader valve core instead. Dont know if it is possible for and air lock or something but the main thing is now I know it is delivering fuel to the rail. Now, if it would only start right. After replacing a dead battrey, I tried starting it and it would only crank & crank and then almost start, but not. I checked for spark leaving the coil and opti whatever its called, and there was. When I tried again it finally did start after about 15 seconds of continuous cranking but it ran a bit rough, especially if I gave it some gas it would sputter abit. I'm guessing that tyhe optiwhatever is going bad or just needs to be retimed??? Any thoughts out there. Thanks