1987 ford f150 keeps starting itself....


Asked by Aug 20, 2013 at 11:58 PM about the 1987 Ford F-150 XL Standard Cab 4WD LB

Question type: Maintenance & Repair

bought a new truck, 1987 ford f150 v8 4x4, drove home completely fine for 120 km then the solenoid started to smoke and truck wouldn't turn over, so I replaced that and worked fine for a hour, until the engine would shut off when I slowed down at intersection, but radio and everything else worked, did this 5 times until last time I tried starting it the engine would keep trying to start itself , only way to stop it was to pull negative wire of post, when I put it back on it kept trying to start itself, so I unhooked solenloid and it seemed to reset itself and worked fine for a km, then the negative battery, seemed like it broke straight off the post, so I got it towed to mechanincs place and they replaced negative and positive wires and new solenolid and starter, worked fine for hour and a half, until it kept trying to start itself again, so I rushed it to farm km away and parked it and pulled negative off and solenoid off again... then started again completely fine........ im lost to whats going on and frustrated.

8 Answers

Michael Tutty

What's happening is that you are getting defective solenoids. It can happen. Finding a 'good' aftermarket one is almost impossible. All of them are made in China now. Just keep taking them back until you get one that works, or try a different supplier, and maybe you will get a different brand. Let us know, please, as I am hoping to buy a 1980 Colony Park, and it uses the same solenoid, and I have almost given up finding a good one to replace a defective old one. Not sure quite what to do if I need one again.

Tracy Hooks

I'm a little confused: The solenoid smokes and fails even though you aren't using the starter? The only time that the solenoid carries a load is when the starter is engaged. Granted - all of your main electrical source is on one post of the solenoid, the other should be un-powered unless you're attempting to start the engine. I have an '87 F-250 4x4 - I have never had a solenoid problem (in fact, In my 30+ years as a Ford tech - I have rarely ever seen a solenoid fail on its own) I've had an ignition switch (electrical) that came apart and did all kinds of weird stuff but it's likely that you have something else going on - causing the overload on the solenoid.

Michael Tutty

Tracy, I have had exactly what the OP has described, and it was a solenoid problem every time. I have also had solenoids fall apart, quite literally, and quite spontaneously. It is very possible for them to stick on, or not to open quite all the way and get a spark jump inside, and that will cause them to smoke, and they can catch fire that way, too.


thanks guys, any information can help, im really frustrated!


Make sure that your fender is grounded and the mounting bolts are tight and not sloppy in the holes, might consider running an auxiliary ground wire to the solenoid mount just to make sure you have a good ground. You could also check with your part supplier and see if they can get you a Cole/Hersch solenoid, I've used the ones rated at 300 amps and never had one fail on me.


Actually your solenoid is fine but you have an extra wire connected to it somewhere. It causes it to be a ghost truck. Check the wiring system and see what's connected and what shouldn't be. The wrong wire will be somewhere towards the bottom left near the solenoid.

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Colin Rivet

might be your ignition switch,check if the power from the ignition wire to the solenoid cuts of once its starts.

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Not only would a defective solenoid cause this problem, but the Ignition Switch will also do exactly the samething. I have two 85 F150s and I replaced the questionable solenoid with the solenoid that I knew was good. When that did not fix the problem the Ignition Switch was the next part to replace. I have not had any problems since.

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