Slow to start then runs fine

This one is starting to frustrate me. All of a sudden my truck takes 15-20 secs to start (sits there and turns over then starts), but once started it runs great (doesnt run rough or anything). I have replaced plugs, wires, dist cap, fuel filter. Any ideas??

Thanks.

1988 S10 Blazer 4x4
4.3 liter, TBI

Fuel pump?

water in fuel?

It sounds like you are either having a problem with fuel pressure bleeding off after engine shutdown or the fuel pump does not energize until the oil pressure switch energizes it. Does the engine have the same starting problem if the engine is only shut down for a few minutes, or only an overnight problem? Either way you want to hook up a fuel pressure gauge up to it, if you can get one you want to T it in to the fuel inlet line on back of the throttle body. You want to relieve fuel presure before you do so, remove fuel pump fuse and try to start engine, you don't want to disconnect the line with a warm engine either for some fuel will leak out. After you hook up the fuel pressure gauge and replace fuse turn the key to the run position, you may have to do this more than once to build up fuel pressure. You should get about 9-14 psi. If you do not get any fuel pressure have someone crank the engine while you watch the fuel pressure gauge, if you don't get fuel pressure untill 15-20 seconds when the engine starts you probably have a bad fuse or a relay or something like that. If you can get a wiring diagram and see what the oil pressure switch bypasses that can help narrow it down. If you shut the engine off and watch the fuel pressure gauge you should not loose pressure, you want to leave it hooked up for as long as it takes for the starting problem to occur, wetheris it 20 minutes or overnight

I am currently going through the same problem with a 92 s-10 Blazer. The error code coming up indicates the ignition module under the distributor is bad. I am going to try my luck tomorrow with it and replace it. If you find something else, I would appreciate hearing from you.

crasen is right about the fule pressure check. another posibility is dirty fuel injectors. s10 have are notorious for dirty injectors and throttle bodies. i would start with the fule pressure check. also, try running a high grade of fuel injector cleaner and several tanks of good gas. make sure you go with good gm parts when it come to plugs, wires, and distributor cap. gm's can be flaky with aftermarket parts, and sometimes you can do more harm than good.

I had the same problem with a s-10 I just bought, I ran the gas out and put in high grade gas, changed the fuel pump and gave it a tune up. nothing worked then I bought a new starter and it runs and start's fine they said the brushes were wore out in it.