We have a 1988 F-350 with the 4.9L 6 cylinder engine that we use in an industrial setting that keeps frying starters and starter solenoids. We are at the point of pulling our hair out because we cannot seem to determine the root cause. The truck has been retrofitted to dump the "blue juice" from airplanes and the pump new "blue juice" back into the aircraft for the lav services. We initially thought that the issue might be in that system so we disconnected all wiring to the pumps and took the starting system wiring back to OEM.
Initially, the battery cable from the battery to the solenoid was melted so we replaced the battery cable with a 2/00 cable and replaced the starter solenoid. (All parts are from NAPA).
Then, the users reported that the starter stayed engaged, even while the key was in the off position. We inspected the ignition switch on the top of the column and found some frayed wiring at the harness. We replaced the switch and harness just to make sure our bases were covered.
Then, I tested the neutral safety swtich and found that it was not working correctly, so it is new.
The ground cable and cable from the solenoid to starter were replaced with 2/00 cable also.
The unit still continues to burn up starters and we cannot determine why. We inspected the wiring from the ignition switch to the firewall plug and from the firewall plug to the starter solenoid and it all looks okay. Have any of you seen this, or, do you have any recommendations of what to check next?

 

It seems like there was an eletric hack-job done on that truck, it would be extremely hard for us to find out what's wrong with it, there is obviously a short somewhere in the system.

 

I agree. That's why we took it back to stock, to eliminate the possibility that the aftermarket system installed on the unit is not affecting the starting system.

 

Yet there is still a short somewhere, since it's affecting the starter and the solenoid I would check the connection at the battery and the ground, you should also have the battery tested.

 

My truck ( 88' F-250, 460 engine) is doing the same thing.The starter wouldn't disengage after turning the ignition switch off and scared the heck out of me..I have replaced the solenoid,battery and the starter..It did fine for a while then did it again..Then the next 2 weeks it was fine.Now it will not even try to start.I hear a hum then a click when I turn the ignition switch but it doesn't do anything else.I do notice my amp gauge go down then up at the time of the noise but it does nothing when I try to start it.Did you ever find out what was going on with your truck?

 

Peggy, you probably got a bad starter, have it warranted and try a new one. The gauge is just showing the starter solenoid is working and the starter itself is trying to engage. It's no news getting a new part thats DOA or that fails soon after starting to work.

 

Thank you.(((HUG)).I will take the starter back.It is warranted thank goodness.If that doesn't work I will have an exorcism performed on it..hehehe

 

Good, see that all the connections on the starter are fine before doing anything else, there is a small flat connector that's famous for becoming loose/corroded/dirty and causing no-start conditions, check that one before anything else.

P.S.: Me likes HUGS! .

 

I just put this starter on myself about a month ago so I know the connector is fine.Yes,I work on the truck myself.hehehe.. And I like giving hugs..lol

 

i have the same issue as the original poster on an 88 f150 4.9l ive gone through 5 starters and solenoids in three months. Ive replaced the battery, cables, alternator, alternator pigtails and wires, and all the fusible links going to the solenoid. also the ignition switch and checked all the wiring as well and i'm stumped.

 

You guys should check your frame to engine grounds. Make sure every thing is clean and tight.

 

i have checked and cleaned up all of my grounds to no avail

 

How long does it take to burn up a starter / solenoid? is it happening right away or is it a slow couple of month process?

There is only two things that is going to cause this
# 1 is bad grounding # 2 you have a short happening,

If you really think it's #2 then pull all your fuses, put back the ones that are needed to make the truck start. Start checking your voltages on systems that should not be energized at this point. If you find power going to an area that shouldn't have any, then you need to back trace from that point to find the affected area.

I also noticed that you didn't mention your alternator, have you checked to see if it's spiking? Having a regulator that runs wide open all the time will surely cause what you're experiencing, also make sure to check your wiring and plugs on the alternator too.

 

it'll go a few weeks before happening again. And I just replaced the alternator and the plugs and wires going into it.

 

I should have posted the solution to my problem. It turned out my flywheel was bad, so the starter was not able to disengage. I had a new flywheel put in and while they were at it I had them put in another ground wire. Check your flywheel. Mine had broken teeth.