I have a 1999 F-150 pickup with a V-6 4.2L engine. It has the original engine with about 132K miles on it.
Until the last few days, it turned over pretty much the first crank. It still turns over very quickly when it’s cold, like first thing in the morning. But after driving for a while and then sitting for a half-hour to an hour, the next startup takes longer, like 3-4 seconds of cranking, for it to turn over. In other words, cold - no problem. Semi-warm - problem. It also starts immediately right after shutdown, probably because there’s still fuel in the line.
In response to this issue, I changed the air filter last weekend (it had been a while), but it didn’t help.
Since the problem appears to be temperature-dependent, could it be a fuel pressure sensor or regulator? A relative suggested that I get a tune-up, but the truck seems to run pretty smoothly once it starts - in other words, nothing appears to be missing.
Any other reasonably cheap things I could try? Is there any good way to diagnose this electronically? There are no check engine lights that I’ve seen.
Thanks,
tmac
Where performance is affected, it’s often not one thing, but the accumulative effect of several things that have hurt the performance… Those parts which haven’t been changed in a while (ever?), should be changed; especially, since an ignition system is the most finicky system on the truck. If you haven’t eliminated suspects, how do you know when they have adversely affected performance? So, change those old spark plugs, spark plug wires, fuel filter, pcv valve.
You can try to shield the starter from the heat of the exhaust pipe by making a shield and holding it on with an exhaust clamp. I drill two holes in the steel to match the u-bolt and use heatproof RTV sealant to glue heatproof gasket material onto the steel. Unless your description is wrong and the engine turns over as fast as it should but just won’t start. Then you may have the other problems.