Have a 1986 GMC S15 6cyl that at tmes will not do anything when I turn the key over and other times it starts right up. What could be the problem?

I agree with you, it sounds like a ground. Black wire, try a redundant ground for park or headlamp.

Neutral Safety Switch ? located at the bottom of the steering column. Mine is tricky, have to pull the shift lever while turning over to get it started. happened after i replaced ignition switch & Neutral Safety Switch

the thermostat is going to be located in a coolant hose. usually the bottom left one if you are looking under the hood. bad thing is is that you will have to also replace coolant. which is a good thing, just a little bit more money. take off the coolant hose off from the block, not the radiator and you should be able to see it. it should be a metal part with a spring in the middle of it.

For this models:
1986 GMC S15/T15 4WD P/U 2.8 liter V-6 VIN "R"
1986 GMC S15/T15 4WD Jimmy 2.8 liter V-6 VIN "R"
1986 GMC S15/T15 2WD P/U 2.8 liter V-6 VIN "R"
1986 GMC S15/T15 2WD Jimmy 2.8 liter V-6 VIN "R"



Hope helped woth this. Remember rated this help. Good luck.

Yes your problem because you have changed the starter then you have 6 bad 1/2 worn teeth on the FLYwheel and the only way to fix your problem is to either remove the engine OR gear box and remove the flywheel and have a new starter ring fitted to flywheel and refit what was removed and away you go finished ...
THEother way to start every time till you do it is to HAND brake off put in 1st gear and turn engine over 1/2 a turn ,and then it will start every time, as the engine will stop the same place every time so thats were the 6 worn teeth are. Have a goodday
Let me know hoe you get on Ron
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every day pump gas pedal 15 to 20 times then turn key starts right up every time

lok for a small hole on the key ring if there is no hole the steering wheel has to come off and a screw has to be taken out for the tumbler and key switch comes out also the horn spring and tang has to be pulled out .

Take off your gas cap and have someone stand there with thier ear at the hole, (no smoking), turn the key to on just before start and they should hear the fuel pump humming. if they dont then try to start. if it doesnt start turn key off and at that instant the pump should be heard again. What i think is happening is your pump is not energizing . Its supposed to energize when turning your key on and off. This can be caused by a bad fuel pump or pump relay switch. Hope this helps. please rate me

They make two relays that will fit but only one will work. Call 772 283-8999 ask for John, He will tell you more than you really want to know, the dude is about the best diesel mechanic I know. You can email him at [email protected]. Tell him Peppi told you to contact him. If John is not available ask for Ron, he is better at GMC products ( no one is perfect ) but he can help you as well. They are real good guys and will take the time to help and can get parts for anything. Hope this helps

1. thats easy to fix the tail light switch has nothing to do with any of that ****