Hello everyone, I've got a big issue. My '76 F-250 (390) is dead in my parking lot at work. It snowed this morning, so I fired it up and drove it to work. All was going fine till two miles from my house. My Autometer tach started to jump up and down the dial and just eventually dropped to 0 and stayed there. While this was happening, my radio was going off and on and it now cannot be turned on at all. The truck made it all the way to work (about 10 miles at least) but it seemed like my turn signals were sluggish and irratic too. I pulled in, and the truck was idling roughly like it wanted to quit slightly but it kept running. Once I shut it off, it didn't even turn over if I tried to start it. I waited two hours went back out and it tried to turn over once but didn't do anything the second time I turned the key (no click, whir, anything). If I turn it to acc. the heating fan still works and the lights come on, etc. So now I need some help because this beast is my ride home....any suggestions? I'm in the process of finding a meter to test the battery...what else should I do? What could it be? Thanks.

Nate

 

Check your connections at the starter relay on the fender.

Also get someone to jump you, and then measure the voltage at the battery with it running. It should be somewhere around 14 volts.

 

Check your fan belt. Check connection at the starter relay. Give the battery a boost and check the voltage with engine running. If voltage is below 12v, then It seems like the alternator has took a turn for the worse, R & R alternator. Will also need to give the battery a slow full charge with a battery charger.
-Buck-

 

Make sure the voltage regulator has a good gound also.

 

Thanks everybody. I'm going to do the tests tommorrow afternoon. I was able to get a ride home from work and I'll go back to check it out when the snow stops (hopefully). I'm certainly hoping its the alternator since that is one of the components that wasn't replaced when the motor was replaced. We'll see. Anyone else have suggestions?

 

PULL OFF AND CLEAN YOUR POSITIVE BATTERY CABLE.

Please?

I've seen this before up in the north.


If I'm right you lucky it cranked.

I bet it has a funny black color on everything.

 

Ok...so I cleaned the battery cables, no change to the condition. The battery is producing 12.5 volts across the terminals. There is 12.5 volts at the solenoid post closest to the battery. When you crank the motor (or try to) there is only about 3 volts on the starter side of the solenoid. When checking the I and S terminals, there is a slight voltage at the I terminal but nothing at the S terminal. I tried to bypass the soleniod and used jumper cables and all it did was spark, no sounds from the starter. All I did was bring the Mustang over and place the jumper cables between them and the truck instantly wanted to start after they were connected for 10 sec. I ran the mustang for maybe 4 min and pulled the cables. Truck started no problem and ran for several minutes. I shut it off and it started immediately on one turn. I think it may be a grounding issue with the truck. I'm going to run several more grounds and check the motor grounding strap. Can you replace that strap? If its the one I'm looking at, its severely oily and looks kinda bad. Any help would be great!


Nate

 

Did you check the voltage at the battery terminals when you tried to crank it? I am thinking if you did, you would have gotten 3 volts there too, because the battery was dead. Measuring the battery voltage with no load will not tell you much, because the battery voltage will "float up" with no load.

Make sure you check the voltage at the battery also when the truck is running, to make sure it's charging(around 14v). It sounds like the battery is good, since it seemed to recover quickly after the mustang boost.

 

Verify all points of contact at battery terminals and starter relay, are clean and are making clean, tight and good contact.

Verify ground cable at engine block is clean and not loose.

Check alternator belt is tighten properly.

Check connection on back of alternator.

Check connection at voltage regulator and check the ground wire at regulator for clean contact.
-Buck-