98 gmc 1500 4.3 4l60e.
starts fine in thew morning when temp is under 60. if it's over 75 in the morning it will take 20 minutes to get started. after initial start up runs fine all day.
new:
spider,distributor,egr.tps,o2,coil, cat, there's more just can't remeber right now.
any ideas greatly appreciated by myself and my wallet.

 

1. cold air has more oxygen. check your air filter, MAF sensor needs to be cleaned, and you might be running rich
2. hot metal expands. cold metal shrinks. micro-cracks open wider on hot. you may have air leak somewhere. take a can of brake cleaner, with nozzle, and gine shots of it all over engine running on hot. if it stumbles at some spot, that's your air leak area.
3. did you read error codes?
4. in what manner it does not want to start?
5. when it takes its 20 minute routine, pull several plugs out. are they fouled with gas?

 

think it's not getting spark . sprayed some ether in the air intake and did not even attempt to start just turned over.cleaned the maf earlier,air filter is new, no codes. brother in law is leaning to bad ignition switch. almost everything else ignition wise is new. how do i check the ign switch????

 

I have a 1998 GMC Jimmy with the 4.3L engine, automatic, 4x2. It starts fine when cold (just bump the key and it's running). But after it warms up and sits awhile, it is harder to start. Meaning it cranks longer (3 to 5 seconds) before it starts. It idles at about 600 RPMs, which seems a little slow to me. I was told that the "ideal" idle is supposed to be 750 - 800 RPMs. Usually, it idles smoothly, but sometimes it intermittently idles rough, then back to smooth again. It accelerates fine and performs fine. The problem is primarily hot starts and intermittent idle issues.


I have replaced the fuel pump (new), new fuel filter, new air filter, new spark plugs so far. The plug wires, distributor cap and rotor seem fine. I have ran the codes and there is only one code sometimes (P0300 - Random multiple misfires). I clear the codes and sometimes it comes back in a day or two. Currently the check engine light is not on. But the problems still exist whether the light is on or off.


Any ideas as far as what the problem is? Help please. Thanks.