Gas Guage help me before I shoot.....

Ok I checked out the guage tech link and checked my voltages and the regulator in my gas guage is putting out the 5 or so volts it is supposed to put out. I have a new gas tank sender that changes resistance like it should, I have checked the temp sender and it works as it is supposed to.both the gas and temp guages work when the key is turned on. I have checked all wiring.... but when I start to speed up going down the street, both guages climb until they are pegged. almost like the voltage to them is increasing somehow. the voltage in the charging system stays pretty close to 12.5 volts at idle, 12.8 or so when reved.

I don't get it. what am I missing?? don't want to burn any more parts up.

 

well after some stewing on the subject, I hooked up my fluke meter to the hot wire to the guages and set it up on the dash so I could see the readout. turned the ignition on and got 12.48 volts, started the engine and got 12.51 volts at idle. as I reved the engine the voltage started climbing. I shut it off just before 20 volts. no wunder the guages didn't like that.

so I decided to have a look at my voltage regulator. there is this rogue red wire that has been bothering me since I bought the jeep. it runs from one of the terminals of the ballast resistor to a point in the harness just before the regulator. well i undid a mile of electrical tape to find out the wire had been spliced into one of the leads into the regulator, but it also includes a diode inline. :? this isn't your standard shadetree harness hack job, someone had a purpose for doing this and I haven't figured out what it is yet.

I am going to assume that the regulator is shot. I also wonder now if something isn't wrong with the alternator, it puts out plenty of juice but there must be some reason to bypass the regulator other than it doesn't work.

and I still can't drive the jeep around

at least through all of this I have not burned the guages up again

 

Ground?

Had some different experience with gauges once on a Stude from the body being so rusted that the grounding strap was no longer completely effective.

B

 

you need go thru all the wires associated with the charging system.....almost sounds like you have a extra hot wire feeding your dash....

 

I'd de-wire the entire charging system and start over again with all new stuff, including a regulator.

 

I'm working through it now. it does not appear that anything else was changed, I think they may have been trying to bypass a bad regulator. I have a new one on the way and I am unwrpping the entire engine bay harness to make sure there are no more surprises.

 

Ground is a good point. I rhinolined my tub and gas tank and couldn't figure out why my gas gauge didn't work. Duh, the sender/tank was no longer grounded. Ran a specific ground wire to the sending unit and BINGO, back in business.

Do you have a swapped in delco with the internal regulator or a stock setup with external? If you have the internal reg you can do away with the external reg completely and clean up some wiring under the hood.

The diode sounds like maybe a fix to prevent run-on of the engine after the key is turned off due to the alt backfeeding into the circuit. Had a problem on a 4.0 ho swap into a CJ using the internally regulated Delco alt that did that. Diode fixed it.

Bottom line though if you are getting 18+ volts it is the regulator.

 

I'm still running the stock Motorola alt. i checked my ground from battery to tub to guage, no problems there.