Amp meter pegged at 30+ (1 Viewer)

[Glacierskier]

So, I have not touched my Jan 72 FJ40 in 8 weeks. All was good when I parked it the garage. All stock f motor, alt and electrical.

On start-up today, started just fine, amp meter fell below the centerline (as usual) on cranking. The moment it fired and ran the amp needle jumped to 30+ and sat there. If I turned the lights on the needle fell to just below 30, still on the positive spectrum.

The leads to the fusible link at the battery were hot to touch. I assume this is bad.

What is wrong and how do I correct it?

 

[Snowdogyyz]

Check your voltage regulator. I had an issue with mine a while back. If you drive with your lights on, do they get brighter as you accelerate and dim as you decel?

 

[Glacierskier]

Check your voltage regulator. I had an issue with mine a while back. If you drive with your lights on, do they get brighter as you accelerate and dim as you decel?

They did in the past. Now, just accelerating in the garage they seem steady and brighter than I have seen them in the past.

 

[bj40green]

Before you start swapping parts.....

Does the Ammeter follow the rpm's?
So zero at idle and up to +30Amps when you rev up?
Maybe your battery was drained but had enough juice for cranking?
What's the battery voltage at idle and how much voltage above 1000 rpm's?

Rudi

 

[Tigerstripe40]

Mine was pegged at 30+
Then I unscrewed the cluster bezel, unbent the needle from the face of the dial and it went back ot the middle.

 

[Glacierskier]

Mine was pegged at 30+
Then I unscrewed the cluster bezel, unbent the needle from the face of the dial and it went back ot the middle.

Nope, not bent. Thanks for idea.

Before you start swapping parts.....

Does the Ammeter follow the rpm's?
So zero at idle and up to +30Amps when you rev up?
Maybe your battery was drained but had enough juice for cranking?
What's the battery voltage at idle and how much voltage above 1000 rpm's?

Rudi

Meter does not follow rpms.
30+ at idle and stays there, slight drop when lights are turned on.
I have not checked battery volts... no meter.

 

[DSRTRDR]

yeah, a multimeter would help

 

[fhawk5]

Without a meter you are guessing. Put a meter on the battery and start the engine. Mine reads about 14.1 volts or so. It does move around based on how charged the battery is and what accessories are on. Now that is voltage.. Current is another thing. Of course having one ,you have the other. A battery can be so bad it draws current as you are saying. Can you try another battery to rule it out?

 

[edwjmcgrath]

If you want to figure this out, you're going to need a meter.
This one is easy to use and comes with instructions. Just plug in the cigarette lighter.
http://www.amazon.com/Equus-3721-Ba...&qid=1370341914&sr=8-3&keywords=voltmeter+12v
Similar ones available at any autoparts store.

 

[Steamer]

A possibility is a stuck regulator. At rest the mechanical regulators sit in the full charge position. The meter is best but while you're waiting on one you could remove the cover on the regulator and physically move it through its three positions. The magnetic coil pulls it into the minimum charge position while the spring is pulling it towards the full charge position. On my rig I can reach around and work it by hand while watching the amp meter go from min to max. Move it first with key off to get the feel and to make sure it's not stuck in full charge position. It moves very little and difficult to hit the middle position but you should hear/feel it move from one contact to the other. (max to min) Look close & you can see the contacts. Make sure they are separating when moving back and forth. And of course be careful not to bend anything. It doesn't take much force. hth.

 

[Cruiserdrew]

The + side of the meter goes directly to the battery. If it's pegged, and the truck sat for a while, the first thing I would think is that the battery is just discharged. Then it accepts all the output of the alternator, which on a 72 is 35-40 amps.

Charge the battery with a charger first. Then start the truck and look at your meter. If it's still reading +30A start measuring voltages.

 

[Glacierskier]

Thanks all, I did get side tracked today when my home h20 heater began to leak. Worked on that today. I will get to amp meter 2morrow evening with multimeter and post my findings/conclusions. Then I will check for stuck regulator.

 

[yzftaco]

I recently went thru this.. Truck sat for a several months, ran fine when parked, Upon starting it I also noticed the needle was pegged at 30. I then drove it to work 30 miles round trip, and the battery charged enough to drop the needle to neutral again.. Been like that since i started driving it again.

I hope that's all you need to do also.

 

[JohnnyC]

I would check all the harness connectors

I kinda recall having an issue like this and it was a corroded wire going into the connector from alternator ... Like I said I kinda recall... It mayhavehad been pegged to neg ... Was when I got the truck 20 years ago

 

[Steamer]

I really thought that if a battery was drained enough to make the regulator go into "full charge" that it would be drained too much to start the engine. Well I was wrong! I just had to test it. I left the headlights on today for 8 or more hours. Just now I started it up (cranked up fine) and the ammeter went to 30amps +. Boy! Learn something every day. I hope that's all your problem is. I did have a stuck regulator once but that was a weather issue when the hood was off and the tarp got blown back.

 

[Glacierskier]

I really thought that if a battery was drained enough to make the regulator go into "full charge" that it would be drained too much to start the engine. Well I was wrong! I just had to test it. I left the headlights on today for 8 or more hours. Just now I started it up (cranked up fine) and the ammeter went to 30amps +. Boy! Learn something every day. I hope that's all your problem is. I did have a stuck regulator once but that was a weather issue when the hood was off and the tarp got blown back.

WOW! Thanks for test! My battery was really low, cranked just fine though. I am charging it now. Also, the regulator internals looked corroded. I found a regulator at rockauto for $11 and $5 shipping. It is on its way.

Leads from the alternator looked a little rough but they cleaned up well.

We will see tomorrow! Thanks to everyone again!

PS; I will post my final findings. I always finding it annoying at the end of a informative thread to find no summary.

 

[Glacierskier]

Summary:

Battery was low, was charged and corrected most of pegged amp meter. However, the voltage regulator, was also on the way out. I replaced it with one from RockAuto, Part; BECK/ARNLEY 1770437 and this completely solved my problem.

Thanks again everyone!

 

[Snowdogyyz]

Glad you fixed it and came back to let us know how! Enjoy driving it now!

 

[bj40green]

Good job, another problem solved

Rudi

 

[nuclearlemon]

i've had issues with aftermarket regulators. you might want to get a spare to keep in the glovebox.