Hmmm. That's true, you make a good point the solenoid is right there next to the thing.
Well.. I... don't know. Maybe it's just rusted out at the bolts that hold the regulator in? Felt ok but it was hard for me to see anything in the dark.

 

Fingers crossed, sounds like you found the problem. As far as grounding the fender, I'd suggest simply fabricating a small ground wire between a regulator mounting bolt and the battery (-) terminal. A short length of 10 ga wire with appropriate ring terminals at each end would be perfect. Following this thread makes me think I should add the same ground jumper on my pickup. I've already added one to the alternator case but I think I'll add this one, too.

Now how was the starter solenoid getting its ground? Even though the fender was somewhat isolated electrically, there may have only been a few extra ohms on the ground path. This may not have been enough to stop the solenoid from energizing, but enough to throw off the precision of the regulator's sensing circuit.

Or the ground path may have shifted through some other component grounded to the now-insulated fender, such as the regulator itself or maybe a side marker light. It's not a perfect ground path but it may have been enough to energize the solenoid. All sorts of strange things can happen in a situation like that. I wonder if turning on the lights caused a stray voltage to energize the regulator base via the now insulated ground path for the marker light in the fender. That wouldn't explain everything, but perhaps it was part of the equation. Just curious, does that side marker light illuminate, and does it get brighter when you ground the fender? Or maybe, as usual, I'm in left field and the marker light is grounded through the harness, not the fender.

 

I did exactly as you suggested, 8 ga with ring terminals. Now charging voltage is 14.7 V no matter what the vehicle is doing electrically, and gauges behave themselves. I will pick up a new battery when I get a chance. I haven't replaced it and I think it's time anyway.

 

Groovy, glad you got it sorted out. Hope I didn't throw too many Clavenistic detours your way.

I looked up the ground to the side marker light. It shares a common ground (G802) with the right headlight, right marker/turn (under the headlight) and the right marker (in the fender).

Take a wild guess where that common ground is attached. It is on the right inner fender, near the front, next to the battery. So if the fender lost its original ground, this newly "floating" ground could wreak havoc with the voltage regulator, since they share the same ground. I'm surprised something so critical as the regulator didn't have a dedicated ground jumper.

 

The starter RELAY is mounted to the fender itself. The voltage regulator is mounted to the fender liner / wheel well. The ground connection between the wheel well and the rest of the cab/frame is hinky at best.

I've read multiple threads here and on the other Ford truck forums, recommending exactly what the OP did, with a dedicated ground wire; my '85 was already wired with one when I bought it.

 

Yes -relay-
I have a pmgr starter with a solenoid...
It is triggered by the fender mounted relay.

I was trying to lessen confusion by using the common (misapplied) term.

Never had a 1G.
If it really is mounted to the plastic inner fenderwell it certainly does need a dedicated ground.

 

Have you made any headway with this???? I am wondering because I have an 1986 4.9l that has similar issues except my truck runs fine until I let the rpms fall while using anything electrical....barely runs and bucks backfires ect. Turn the load off and rev up the engine and everything goes back to normal. I have been trying to figure it out for months!!!

 

Sorry I may be posting at the wrong place but I did all things mentioned above to no avail

 

Welcome to the forum, Will Janoske!

Please start a new thread and tell us about your truck and its problem. We will attempt to assist you!

 

Yeah, hijacking somebody else's thread (even if it's old and done) has never gone over well here....

 

I am really sorry I can't figure out how to start a new thread can you please point me in the right direction?

 

Go to the front page of this forum, then click on the button.