Tune-up help with parts ??????

I have a 1998 (150,000miles} with a 5.7 engine that is idling ruff and the starter has to turn over a long time to start the engine when warm. When cold it starts normally. The engine light is not on and I checked for a code but none found. I replaced the plug with AC Delco. I am old school and not sure what else to replace. I am going to do the wires and rotor cap next, but what else should I replace? Thanks Dave

Hard starting when warm is most likely a bad fuel pressure regulator. The bad news is that the top half of the intake has to come off to replace it.

If you never had the intake manifold gasket replaced (they tend to leak), then you should have it replaced when the fuel pressure regulator is replaced.

If you have a fuel pressure gauge, hook it up and start the engine. Turn off the engine and watch the pressure. It should hold 60 PSI for a little while. If it drops fast, the fuel pressure regulator is bad.

//2000CAYukon

Thanks for the reply. Would a bad fuel pressure regulator also give me bad soot in the tail pipe?? My new post is this. I have a 1999 with a 5.7 engine in it and 150,000 miles. It starts right up on the first start of the day. Last week it got real hard to start when the engine was hot. You have to turn the engine over a long time before it cachets. When it dose cachet the RPM are about 400 and then slowly moves to 600. I replaced the plugs but that did not help. I noted that the tail pipe had a LOT of black soot in it. I also have 1996 5.7 and looked in that tail pipe and saw very little soot. Any ideas on how to fix the starting problem? Any help or ideas would be great. Thanks Dave

Thanks for the reply. Would a bad fuel pressure regulator also give me bad soot in the tail pipe?? My new post is this. I have a 1999 with a 5.7 engine in it and 150,000 miles. It starts right up on the first start of the day. Last week it got real hard to start when the engine was hot. You have to turn the engine over a long time before it cachets. When it dose cachet the RPM are about 400 and then slowly moves to 600. I replaced the plugs but that did not help. I noted that the tail pipe had a LOT of black soot in it. I also have 1996 5.7 and looked in that tail pipe and saw very little soot. Any ideas on how to fix the starting problem? Any help or ideas would be great. Thanks Dave

Yes. If the fuel pressure regulator is bad it can dump extra fuel into the intake (thru the vacuum line) causing a rich condition. Black soot is usually from running rich.

//2000CAYukon