Electrical (charging) problem

Ok. I've got an electrical issue here that is pretty specific. - I'll start at the beginning:

I was born on December 29th , 19... Well, maybe I'll skip ahead a bit..

I noticed that the fuel gague was reading high one day. I noted it mentally, but since it's not my DD, I figured I'd get to it later. Then the next weekend that I took the jeep out, I noticed that the gage was pegged all the way past full. (clearly malfunctioning to the point of being useless), but again, I just ignored it.

Then the next weekend I was headding to a trail ride the night before an early run and when I turned my lights on, the engine almost died. - I ended up just going with my brother in his jeep, but that's not really part of this story -

So since the alternator was 17 years old, had 250,000 miles, and squeaked weirdly, I replaced the alternator. Then I started the jeep (after charging the battery) and I put a meter on it to find 11.9 volts while it was running. I brought the alternator back and had it tested and found it was good. So I reinstalled it and started looking at other things.

I replaced the main line from the battery to the starter (it absolutely needed it, but didn't help this problem) and I replaced the fusable link between the alternator and the distrubution block... - nada.

So I traced the lines that ran from the plug in the alternator and found that one of the two disappeared hopelessly into a wireing harnes, and the other went into a 6-wire weather-pac connector next to the battery, THEN dissappeared hoplessly into a wireing harnes.

I - just for a laugh - started the engine, and unplugged the connector. I heard the engine instantly go under a load (the idle responded accordingly) so I put a voltmeter on it and got 15 volts

So here's where the gas gage comes into play... Well, after I brushed out the contacts to the best of my ability I reconnected the weather-pac and was still getting 14.7 volts. (aprox- analog dial). AND the gas gage was working. I drove around the block with my lights on and checked when I got back and was still charging. SO I figured I just had a corroded connector, and I was done.

The next weekend, the gas was reading wrong. and sure enough, when I checked, I was not charging the battery. SO I pulled the connector and checked while the connector was unplugged to find that the gas was still pegged, and that the engine was indeed charging again. I reconnected and once again the gas was working and the the system was charging.

So my question is: Do I just need to replace that connector (which looks good, and I haven't heard of them going bad very often), Or do you think I have a short that is some where ( I personally am affraid that it's likely, considering the age) and is just giving me the ol' head-fake with the connector?

Or is there another explaination that I'm missing?



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Fozzy_Bear said:

So my question is: Do I just need to replace that connector (which looks good, and I haven't heard of them going bad very often), Or do you think I have a short that is some where ( I personally am affraid that it's likely, considering the age) and is just giving me the ol' head-fake with the connector?

Or is there another explaination that I'm missing?.

Click to expand...

I think you have a short or bad ground.. Make sure the engine is grounded to the firewall and that it's tight.. Of course, check all your fuses and relays.. Next, I would trace, test, and diagnose your fuel gage and wiring..

*15 minutes later*

After thinking about it.. I have no idea.. Was thinking the starter relay could be bad.. Maybe a bad battery, should read 12.5v +-.1v. Could even be a bad u-joint ... :wierd:

Anywho....

Elias
Eh-lee-us
Or "E"

Replace that battery. It has a shorted cell in it. That should fix your Voltage issue. I doubt serously it has anything to do with the fuel gauge though.

Concur on the battery - also, check the ground strap from the engine to the firewall. Since you said "17 years," I'm assuming it's RENIX, and that ground strap is the only ground for the chassis to the battery (RENIX = 1984-1990 w/AMC gasoline engine.)

The Delco CS-series alternators that AMC spec'd are actually pretty tough - I'd take them over the ND - but a bad ground is a bad ground, and I've traced a LOT of automotive electrical problems over the years to bad grounds.

If you go check the HELP! section at your local parts house, you should find a three-tool "Weatherpack Tool Set" - two flat tools and a "sleeve on a stick." That last is used to remove terminals from the plastic housings, and it makes for a more effective job of cleaning them. I use cheap toothpaste and an old toothbrush - rinse well before reinstallling! Toothpaste has no solvents in it and a VERY mild abrasive, which makes it excellent for removing oxidation from electrical contacts.

While you're checking the firewall ground, it's a good idea to clean that patch on the firewall down to bare metal - about the size of a postage stamp should do - and apply corrosion inhibitor on reassembly. This ensures a good ground - even the threads in that screw hole are painted, which doesn't really help...

5-90

Could it be the fuel tank sending unit has a wire shorting out, just a thought! That would cause a full tank reading.

fuel tank sending unit is called a potentiometer it has coils of wire wraped around and a little slider arm with a float that moves over the wire wrap sending the signal for each wrap telling your gauge how much fuel you have. If it goes you peg out because it grounds. If you have an electric oil gauge remove the wire it pegs. Or the hot wire leading to it or sending wire to gauge. These are simple setups hot in signal out. Hope this helps

Thanks all.

I'll redo the ground and replace the battery and weather pac. (yeah, it's a renix with a quarter-million miles on it. So anything I replace can only do more good than bad.)

Heck, I'll probably add another gound line (or two) while I'm there. I've been planning on running a ground strip to the rear to get a good ground for my electrical OBA and serious stereo equipment (near future, but not installed yet) So I might as well make sure the ground I tap is solid.

I'll post back here once I have it done... But I don't expect to get much work done during the week between christmas and New-Years.

EliasJ123 said:

...
Could even be a bad u-joint ... :wierd:

Anywho....

Click to expand...

Naw, I replaced them recently when I had it on a lift filling the blinker fluid. (the blinker drain plug is a LOT easier to get with the jeep on a lift :jester: )

- good thought though...