My original fuel gauge went out, so I got a new autometer to replace it. The new gauge pegs all the way passed full regardless of fuel level. I'm trying to figure out if something else out of whack, or if I have the gauge miss-matched.
The gauge is an Autometer 10-73. 10 empty, 73 full.
The sending unit is for an MTS 21 gallon tank (this worked with the original fuel gauge, so should not be related to the problem at hand).
The gauge is currently only using the original wire to the sending unit. I have checked this wire for a short to ground, and it reads open when disconnected from both the gauge and the bullet connector near the sending unit. When plugged in at the sending unit, it gives an ohm reading that roughly matches what the fuel level should be, i.e full reads 75, half tank reads 25-30-ish, and I never run it empty so no idea below that range. So this wire should be in tact.
The gauge has a direct fused and switched power feed from the battery as per manufacturer instructions. The power, ground, and sending lines are all connected to the proper pegs. I've checked this at least 10 times to make sure I'm not crazy.
The sending unit has a new ground feed. This is run to a brass bolt I installed in the back of the Jeep when I had the fuel tank down to swap it. This grounding peg is a dedicated ground with a wire feed straight to the negative battery post.
Has anyone else installed these? Should I change the power feed to the pulsing feed that the original fuel sending unit used? Could the fact that I used a dedicated ground, rather than a body ground, affect the fuel gauge's reading? Should I chalk this up to a manufacturing defect and resign myself to purchasing a new gauge? I've checked the sending unit post of the gauge to see if it had an internal short, but that checked out ok. I'm not sure where else to look at this point.
If the sending unit worked with the original guage and the original guage no longer works and the replacement guage won't work either could the problem be the sending unit?
I share your frustration. Last year my speedometer went balistic and made so much noise I pulled over and disconnected the cable. Then the turning cable wiped out the fuel and temp guages. New cluster restored speedometer and fuel, but not the temp guage. Assumed bad wire and rewired--no luck. Replaced temp sending unit--no luck. F___ it! Got aftermarket guage (that I can see better) and installed it. Had to install sending unit that came with guage to get it to work. Won't even discuss the oil pressure meter which pegs when I turn on the heater fan! Next winter's project is rewiring the whole Jeep. There is a right way, a wrong way, and the Jeep way to make repairs!
If it has rollup windows and A/C it ain't a Jeep. It is a rebranded Dodge!
I may have reversed those figures, it's been over a month since I had time to look at it. Working out of town has a funny way of stalling projects lol. I'm heading over to mess with it now. I have my DVOM on me, hopefully the test light is in the CJ.
I feel you on the speedo gauge man. Mine wiped itself out a week before I got my new job. My temporary solution was to download a phone app called Digihud.
I love longshots.......IF it was initially a float problem, it would just read empty all the time. A new gauge would not address that, but would still read empty all the time. Unless...the new gauge were actually as the OP has stated: 10 empty & 73 full (reversed from OEM), the float would still be on the bottom of the tank and the gauge would read full regardless of the level. A quick search doesn't turn up any Autometer fuel gauges with 73 Ohm full, but another common fuel gauge setup is a 0 Ohm empty/90 Ohm full....which might look like a pegged FULL fuel gauge with a 10/73 sender that has its float on the bottom of the tank.
Just a thought, using the facts as presented. Can you share the Autometer model #?
Mild dyslexia, it reads 10-12 full.I checked with a voltmeter. I tend to get things backward from time to time lol. But yeah, it's got to be a case of dead gauge from the factory. Everything else checks out no matter how many times i look or what angle I look from.
Dang. I was really hoping it was the 0/90 style gauge.
I would say take the sender out and test it directly against the gauge. We never established the initial problem (at least we didn't in this thread afaik), so it's worthwhile to start eliminating variables and actually put hands/eyes/voltmeter on the subsystem; actually manipulate the sender to see the effect on the gauge. But that's just me. I'm lo-fi.
Been there and done that. The sender is new, and last I checked (after old gauge quit, and before breaking down and installing new gauge) it worked like it was supposed to. As far as I can tell based on the ohm readings I'm getting between fill ups, the sender is still in working order.
The one thing that does have me a little leery is every gauge on the dash seems to be having trouble of some sort. The voltmeter is reading 12 volts, but the alternator is charging at 14. The factory fuel gauge is shot. The factory temp has a mind f it's own. And I'm not entirely sure I trust the pressure gauge at this point either.
Part of me is starting to wonder if the dash doesn't have a small amount of current running through it at this point. I installed a dedicated ground to the dash panel a while back, and last I checked that ground was still good. But if there was just a little current leaking in from somewhere who knows what kind of havoc it could wreak.
Got it! New Guage came in today, and it behaved the same as the one I had previously installed. So I went back to checking wore feeds.
Connected the dvom to the power feed and dedicated ground I ran specifically for the new fuel meter. Had 12 volts and assumed that meant both wires were good. That is where I was making my mistake. So I checked resistance from the sender wire and the group feed, It returned 60 ohms. Filled up this morning and maybe drove 8 miles, so I knew something was off. Changed grounds and the reading was 12 ohms - the proper reading for the full tank I had.
In short, the brand new ground wire had resistance somewhere and was probaby split in the casing. Go figure.
I'm curious to know what it did (if anything) to help your other gauge issues.
I was stupidly confident it wasn't the brand new gauge, especially an AutoMeter. There are no shortage of 100% legit stories here of people having all sorts of issues with brand new or re-man'd parts. However, I have never even once experienced this, so I remain skeptical (as is my nature) of new parts being the issue. Especially given that so many other things could be the culprit. Now that I've said this, I'm sure my next 10 new parts will all be faulty out of the box. Glad you got it worked out, and that it wasn't anything more sinister.