Hey guys...
I have a 74 F-250 highboy, and am having a problem with the truck not charging. I have had the truck for about a year and this problem is haunting me!
I have replaced the battery, alt, and external reg.
With a multi meter the battery always shows 11.5v running or not. The headlight are bright, but i know the voltage is not right! The truck starts great if its cold, but once its warm and you shut the truck off, game over! wont start back up (and AAA is tired of seeing me )

The worst part is, the truck has had many owners, and everyone of them did more of a hack job on it than the last! Has takin almost a year to get most of the bugs out. If i can kick this one i think it will be road worthy, but everytime i fix something i think shes ready, and its always too soon. Im not giving up on her! shes my dream truck and i want everyone of my repairs to make the truck more reliable!
Please help if you can i cant seem to track the prob.

 

Mayby you just replaced faulty parts with more faulty parts? I've gotten bad rebuilt parts from the auto parts store already that were worse off than what I started with.

Hard to say with out seeing it ya know? Maybey someone else can chime in and get you a better answer?

 

Are you losing all power? Does the truck have headers? Could be the starter is getting hot, reducing its efficiency.

 

yep, the starting issue kinda sounds like heat soaking in the starter rendering it useless until it cools... very common problem with headers, but have seen it happen with manifolds.

I recommend that you have your alternator tested by a parts store... The big chain parts stores test alternators for free, so i'd start there. Even tho you already replaced it, there is a chance it could be a bad replacement part.

Do you have an amp gauge in the cluster, what is it saying?

I'd start with the free alternator test.

When you say it won't restart, does that mean that you could run it for hours, but as soon as you shut it off it won't restart? Do you have to charge the battery frequently? If not, then your problems aren't that your truck isn't charging, it's that your starter is weak/flawed when warm (heat soak). OR, is it that the truck runs off of the battery when it's running, and when you try to restart it the battery doesn't have enough juice?

If your truck doesn't die when you run it with headlights on for long intervals, it probably isn't the charging system. You may need a new starter, and a new voltage regulator, 11.5v is low.

Good luck,
JT

 

Hey guys,
I took the alt to auto zone to have it tested and it passed.
The truck will run for hours, but like you said once off, wont restart...
In the year that i have had it its had the starter replaced 4 times! Keep getting crapy starter after crapy starter ( luckly it has lifetime warranty)
The truck has manafolds. Yes there is an amp guage, and when the truck is running its at 0, but when you turn on the lights it shows a drop in amps. When the truck is running if you pull off the battery cables it dies, and im pretty sure that means the alt is not doing its jod?!

Just a question, at my last visit to autozone, during my tantrum i threw while i was there (i get all my parts there) some old man was tring to explain that sometimes you have to polerize i believe he said the external regulator? He said by touching two wires together it would spark and make the regulator to start working???
ever heard of such a thing? sounds like it would short the regulator. Or is that some old trick to these trucks?

Again thanks guys!

 

DON'T try to polarize your regulator! Your will burn out your wiring harness.
This is something that had to be done when they used generators instead of alternators.
Also, 11.5 volts is too low. When the engine is running the voltage should read around 14.7 volts.

 

Run a jumper ground wire from the engine block to one of the regulator's mounting bolts and see what that does to the running voltage.

Also - does this truck have an ALT light or an ammeter on the dash?

 

Yeah I thought the old man was crazy! lol Thought i would check...
Yeah also i think the problem is itermittin (spelling is bad) The prblem comes and goes. I just went out side to start the truck and starts fine, but last time i brought it home from a long drive(60 + miles) and turned it off it acted like the battery was dead.


no light on the ammeter

 

That's not what I meant - there were two options at the time, an ALT light that would come on if the alternator is not charging, or an actual gauge. I ask because the wiring harness changes between the two. Are you saying you have the gauge?

You need to try the jumper wire test I described. I can't help you unless you diagnose things step by step and provide feedback.

 

lol sorry now i understand...
I have an amp guage.
Its too late to run your test tonight, i was just letting you know what i have done thus far, and the starting of the truck was only to see if it would start, my dad was curious...

 

fmc400, he stated he had a guage, u must have missed it.

Bretts highboy, make sure your grounds are good, as suggested, run a thick cable from your neg. battery to a nice *clean* metal ground on the engine block. That would over rule any grounding issues temporarily.

JT

 

Thanks for the clarification, I must have missed that earlier. Let us know how the test goes.

 

The 11.5 volts engine off is a concern, the battery isn't charging and something is pulling it down.

You might have to run a test light/ DMM and start pulling fuses to see what circuit is messing things up.

Josh

 

ok sounds good, is this the same as the other guy wanting me to run a wire from the block to the reg mounting bolts? sound like it just checking though?!

 

yeah sounds like something is pulling power when its not running! will try all of this tomorrow! The more the better, as far as test go. would love to finally kick this prob.