hey guys i have a 1988 f150 300cid that i just got back on the road after new rear suspension work and while i was on my way home i noticed all the lights gradually dimming out over the course of about 15 minutes and the volt gauge reducing charge so when i got home i shut the truck off and tried to turn it back on and that obviously didnt happen, but im wondering if its just a junk battery or if my alternator is shot, ive never seen the gauge actually go down like that while the truck is under power, thats why i think the alt is gone, anyone know???

 

If it was your battery your truck will run fine. If you have a volt meter you should ck your volts when its running. Should be like 13.4-14.5. Ck that and let us know.

 

I should probably start a new thread, but I have a similar problem. Went xmas shopping with the gf last night and took the pickup. A 94 f-150, 302, 5spd. It was around 0 outside, so I figured I'd just let it run like I have many times before. Came out of the store a little while later and its dead. I jumped in and the lights on the dash were very dim and it wouldn't turn over. I got a jump and it started right up, but after i had put my jumpers away and started to walk back to the drivers side it started to idle slower and slower until it died before I could get back in. I hooked the jumpers back up and let it charge a bit and it started again.

I revved it for a min and then unhooked and took off for home really quickly. I noticed that when it sat idling the volt gauge seemed low and when i revved it, it would go back to normal. Put my volt meter on it at idle and only got like 13.33 volts and it seemed to be going down. When revved back up it goes to like 14.5. I know I've checked it before and it was around 15 just when idling. I'm assuming its the alternator, but my brother thinks maybe a bad battery. The battery is maybe 9months old, so I don't really think thats the problem. I can't get the alternator tested until Monday. Is there any way I can check the alternator myself? I can get hold of a load tester for the battery and will make sure it is charged all the way before I test it.

Any other suggestions???

Thanks,
Matt

 

Ya wildcat you should start your own thread, because your problem is totally different.

And if you shut off your heater blower your problem would probably go away.

 

Vladimir, that doesn't sound like a battery problem.

It's a charging problem.

You might check for loose fan belt.
Check for loose wires or blown fuseable link in alternator wire/wires.
Have alternator checked.

 

see if the belt tensioner is stuck

WITHOUT THE ENGINE RUNNING!

 

ac700wildcat

Matt it sounds like you have a brush problem in the alternator. You can have the alternator tested and if it is bad and the bearings sound good you can buy a brush & regulator assembly at the auto parts store and just stick it in the alternator with four screws. You should be good to go. Have them retest it. That is about all they are going to do when they rebuilt the alternator anyway.

If you had the heater running on high while in the store it is possible that the battery discharged while idling like netscaner said but it should at least hold its own going down the road.

 

got it figured out, just turned out to be that the clips on the harness on the passenger side of the alt broke so the plug came out and wasnt keeping charge on the battery

 

Thanks for the reply subford. I've left it running the exact same way hundreds of times in the 7 years I've had the pickup and this never happened before. I took the belt off and the bearings don't seem very great either, so I guess its time to find an alternator. May just have to wait til after xmas to get one for a decent price from a bigger town. I guess I can at least yank it and get it tested tomorrow.

 

I actually had the same problem last month. I was driving down the road and noticed the voltmeter going down. I went home and turned it off. I Then tryed starting it and it would start. To make the story short my alternator had went and killed my battery too. To me it sounds exactly like the alternator, and while your at it make sure you charge your battery and/or get a new one, before you put the new alternator on. Hope this helps.
-Pat
1994 F-150 XL
Inline 6

 

Sorry i see you figured it out.