Having issues with my battery not staying charged. I have read many of threads but none state where the grounding locations for my 351M are. If someone could enlighten me I sure would appreciate it.

 

Negative battery cable grounds to the engine block.

But I'm thinking that the problem is something other than a ground.

 

I just went through the draining battery problem a month ago. It turned out to be a bad voltage regulator. Here's a link to the thread https://www.ford-trucks.com/forums/1...g-battery.html

Much good info from people in this thread.

There are many grounding points too. Battery to engine, engine to firewall, frame to cab, frame to bed, hood to firewall and a few others I think.

Dennis

 

X2 on all the good places mentioned above and here is an good extra one. Do you have any aftermarket stereo equipment or driving lights hooked up direct? Research parasitic drain...

 

Thanks for the info, I have no extra accessories, all stock except for the new Edlebrock intake (2171) that was installed last week. The mechanic deleted the emissions system without even consulting me so I didn't know if he might have missed something when putting it all back together. I was trying to look back through what little pics I have of the motor and didn't really see anything. Does the alt suppose to have a ground directly to the neg terminal in these trucks ?

 

Read your thread. Very interesting. I have tested the battery, alt test, checked for parasitic drain as 77&79F250 mentioned, all before I left work and everything checked out good. On the way home I stopped for gas was in the store under 2 min, came back out to no start and had to get a jump. Got home, tested battery=good, tested alt=good, and began the drain test=good. In your opinion should I start by replacing voltage regulator? Do you have the part number from yours by chance ?

 

I just went out and looked but I must have thrown the box away with the number on it. I just bought it at O'Reilys anyway. I'm not the person to give advice on auto electric problems, that's why I started that thread. I did change my starter relay 1st and had no change. Then the voltage regulator fixed it. If you drove it to the store and it was "dead" when you came out maybe there is a loose connection somewhere. I had a random no-start on a 96 Blazer last year and found the battery negative cable was loose. It would sometimes start with the remote start, sometimes with the key and sometimes not at all.

Check all of your connections again and maybe someone here can help you. Do you have old battery cables? If yes, toss them and buy new so you know they are good inside the insulation.

Dennis

 

Understood. Yes, made all new cables here at work yesterday and went with the setup like the pic from post #4. Brought my meter with me and tested the battery when it wouldn't turn over, 12.8 V. Going to get the regulator today and try it out. I’ll post the results later. Thanks for the feedback.

 

Just had this problem with my 73. Put an all new wiring harness from American Autowire and everything worked great for about 6 months. Went out and started it no problem. Let it sit for 30 minutes and had no lights or anything. Changed batteries (had an extra laying around) still nothing. Got it back in the shop and turns out the negative ground from the battery to the block was loose where the battery post connector goes. Cut it off and fixed it reattached and now it starts on a dime. Just something to check but I see you got new cables so hopefully that eliminates your problem

 

Had similar issues and in my situation it was the voltage regulator

 

Thanks for the feedback fellas !

 

How did you test your battery?

 

Make certain the end of the battery ground cable going to the engine block is mated tightly to a clean surface too. Your problem sounds eerily like my 96 Blazer problem.

Dennis

 

I consider it a great day when a battery still tests good after draining a few times!
So are you measuring voltage at the battery when the engine is running? Aside from load testing a battery, and machine-testing an alternator (was it on the vehicle, or did you take it into a parts store?), there are still other things such as wiring, and yes, the voltage regulator. Some of them can be tested as well.
But when the engine is running you should see over 14v on the battery terminals. You can carry a cheap volt-meter with you to check this at various times.

If it's less than 14 then it's not charging efficiently. If it's less than 13.5v it's barely charging at all, and likely why it works for awhile but just can't keep up with things.
Measure it just with the engine running, then measure it again after you turn on a few things like headlights and heater, and maybe flashers too. A good system can maintain 14.5v during all this.

You can check the regulator connector as well. Does yours have the more common 3-wire setup, or the 4-wire setup that's used when the instrument cluster has lights instead of gauges?
Do you have an ammeter on the dash (working or not!) or just a battery light? Sounds like you have an ammeter, but need to confirm to get the wiring correct.

But testing the regulator wires is easy either way. The Yellow should have full battery voltage at all times. Measure both, and if there is much of a voltage-drop you need to find out why.
Green w/red wire gets 12v when the key is ON only.
Orange wire is variable and not much to test here at this level.

Good luck.

Paul

 

Sounds like it might be a good time for a "full field" test! I've never done one, but I've read about them here.

It is my understanding that a full field test will prove the alternator good, as it bypasses the regulator (I think.)

However, if the rectifier diode(s) go bad in the alternator, then the alternator will drain the battery when the vehicle is off - even though it might still charge just fine, and the regulator is still good.