No Start Diagnosis HELP!

[acre44]

I have been lurking on this site for awhile and I have to thank everyone for all the great tips. I have solved so many problems with my 1999 Grand Prix GT by way of this column and saved lots of $$$ in the process.

My 1999 Grand Prix GT with the 3.8 NA and no mods has started acting up. If I drive it for awhile and shut it off she refuses to start. The engine turns over and it sounds like it wants to start on 2-3 cylinders but then dies. I tracked it down to the fuel pump due to the fact it is not priming when it won't start. It never does this cold only when up to temperature and driven for awhile. My understanding is that the NA 3.8 does not have a fuel pump RESISTOR. I checked under the battery and no dice on the resistor. However in the fuse block under the hood right next to the battery there is a fuel pump RELAY that I did in fact change for $30.00. This did not solve the problem for a little while. When this happened recently I opened up the fuse block under the hood and tapped the relay and she started right up. I am not sure if it is another bad relay or if it may be the connections or if possibly it is getting to hot and maybe I should insulate it? Any ideas would be appreciated!

Thanks again! :o)

[GTP Dad]

It sounds like the relay has gone bad again. The question to ask is what is causing the relay to go out? It could be the fuel pump going bad or it could be a bad fuel pressure regulator causing the fuel pump to work all the time and thereby causing the relay to overheat. I would check to see what the fuel pressure is at the fuel rail. You will need a fuel pressure guage and simply connect it to the shrader fitting on the fuel rail. Start the car and have someone rev it. Watch the pressure it should be between 45 and 55 pounds. If not replace the fuel pressure regulator. The bad relay could also be caused by a fuel pump going bad too. I know you said you put a new one in but it could be the culprit as well. Since you said it only does this when hot the fuel pump may be overheating causing the relay to fry itself. Just some ideas to possibly help you out.

Welcome to the forum!!!