1988 F-250 alternator problem
 

Well to start this off, I'm not a ford mechanic.
I just got this truck. It was cheap and I needed a truck
To move stuff around my property.
The truck runs like a new one it's a fuel injected 7.5 460
5 speed, someone has rigged a push button to the solenoid
and the truck won't crank off the key switch, but it will off
of the push button.
I'm not sure if that could have anything to do with my problem.

I bought a new battery and it cranked fine...... Once.
Then when I killed it, it wouldn't crank back up.
So I charged the batt and it cranked fine. But it's not charging
the amp gauge is showing low batt, no where near 12/14 volts
But I have been told that if the back of the alternator is magnetized
then it's charging. Which it is magnetized. And all of the connections
are clean. But it still will run a batt dead and then not crank.

I'm lost. They're are 2 wire plugs on the alt with 3 wires each
and most of them are hot when the key is on.
I searched google looking for a diagram and didn't find anything.

Another thing I tried. Which idk if it applies to fords or not but
I unhooked the hot cable from the battery and the engine died


Any help would be greatly appreciated. Any thing I could
check or try or any suggestions??

Justin

This would make me look for the voltage regulator gadget that controls how the alternator charges (or not) the battery. For better or worse, that's all I can think of.

Could be a regulator; won't allow the battery to charge. But it should take a few hours to run a full battery down.

The starter solenoid; It might be 'open' after starting and draining the battery.

I could be the ignition switch; shorted and draining the battery. The push button may have been an attempt to fix this, but their are 2 power wires to the ignition switch and the push button probably only has one.

Could be a short somewhere else.

Not much help here, I'm sure. Ford electrical systems make me want to kill small animals. I hate them.

I think the alternator has an internal voltage regulator, but I'm not sure. In any case, pull the alternator and have it bench tested. That will tell you whether or not the alternator is good. Buy a service manual, it will come in handy. No matter what the test results are on the alternator, undo the mess that you have going on w/ the ignition switch. Your issue may be a combination of things, but start w/ the obvious.

Well I figured the Ignition switch problem out, the solenoid wire was broke
So I fixed it and now I cranks off the key.

As for the alternator, I pulled it off and had it tested and it failed miserably,
8 volt peak was all it had.
So I've got to get another one for it.

Thanks for the replys. I do appreciate it.

Put an alternator and its up and running like a champ.

Great news! I'm glad to hear that you seem to have solved the problem.

good job. logical deductions ftw

Now I wish I had an F250 since I could use one a few times a year.