Hi there,

My 1990 F25O has recently been shutting completely off and locking up as I'm driving on the road, (more commonly as I'm making a turn). I have to turn it back on and then it's fine again for a while. It has no problems starting, it only happens as I drive and I'm not sure what is going on. This happens very often now, even if I'm just going around the block. Three or four days before this became an issue, my power windows and windshield wipers stopped working. I'm not sure if they are related, but it seems like they could be. I replaced the 30 amp circuit breaker for the power windows and that did not solve the issue with the power windows not working.


Also, it has been a common thing for my truck to shut off in a similar manner whenever I hit the button to engage my secondary fuel tank. When I hit the second fuel tank, the truck shuts off and that has been the case since I purchased the truck. The main issue, my truck shutting off in drive when making a turn is the newest and most serious issue I have. I share the additional information to perhaps help troubleshoot or help solve why my truck is now shutting off when I drive.


Any help offered with this issue is greatly appreciated. Thank you,


Wil

 

It does sound like there is a poor connection in the circuit supplying power to the fuse panel inside the vehicle. A good place to start would be to start at the battery and trace the wiring from the positive battery post which I believe goes to the connection at the starter solenoid then up to the fuse panel inside the vehicle. There have been times when the fuse panel became wet and corrosion at the fuses caused problems like this.
A thorough visual inspection may help locate anything that is unusual, loose or may have a poor connection.
The symptom you describe seems to indicate that whenever a load is placed on the electrical system it can't provide sufficient power to keep the engine running.
Last, but not least, check for any poor ground connections.

 

Thanks so much for your help. It was identified that it was an issue with fusible links that had burned out.

 

Glad you found the problem.
Something to keep in mind, usually a short circuit or excessive electrical load will cause a fuse to blow immediately. So that is why we have fusible links to handle very short term excessive loads without blowing a fuse and to protect the circuit wiring. There might be a problem lurking where something is drawing excessive current for a short time ,,,,,,often ! And the link is doing it's job, but if not found and corrected it could set up a repeat performance up the road. Might be a good idea to have the system checked for anything that may be pulling more current than it should. It could have been something from past problems that left the link in less than good condition.

 

That's interesting that you mention that. If I have the radio on and engage my power windows, the radio shuts off momentarily and comes back on. I just got my truck back today from the recent repair and it's running fine again although it still does this with the radio. I was wondering if it was too much on a circuit. I would hate to have a repeat issue. Could this possibly be what you are referring to?

 

The other issue mentioned by the mechanic is that the ignition switch was defected. He had to replace it with the fusible link and mentioned it could have been the cause for the link going bad. But now I'm wondering about the radio/power window issue mentioned above as well. Especially since it is still ongoing...

 

You mentioned a few items that should have the current draw checked to see how much each is drawing. ( # amps)
The second fuel tank pump and sender seemed to pull enough power to cause the truck to shut down and that could be due to a locked fuel pump. If you never hear it run , either the power to the pump is short circuited or the pump could be jammed.
Speculating doesn't do anything . Current draw should be in the area of 6-8 amps.
If there was any problem with the power window system it should cause the circuit breaker to open. Do you know which fusible link had to be replaced. There is more than one and it would help if we knew what was powered by that link aside from the ign sw. Have you had any other problems other than the radio cutting off?