Gas gauge just dropped to Empty

[Patrick Morris]

Originally Posted by 76-scout-MATT

how big a hole and where

The hole I cut is roughly 5" x 5". It's right along the center line of the vehicle. I wish I could tell you precisely how far fwd it is, but I'm not home this week to take a measurement.

Unfortunately, I don't know if there's a way to make the hole without dropping the tank at least one time. I think that a jig saw is the only practical tool for the job, but there isn't enough clearance to use one unless the tank is lowered at least a few inches.

[Thomas]

--The ground at the frame would be what I'd suspect first (especially since you're in the Great Lakes Salt Belt [lovely winter road treatments] and in Michigan), where cancered vehicles will never be a thing of the past. The grounding screw is pretty much behind the right rear tire no matter which of the two areas it's in. It will either be on the inside of the frame pretty much below the right side, rear marker light or it will be on the inside of the rear, frame end cap, pretty much below and between the tail light & license plate light. You won't be able to miss it once you locate the common screw that holds rear grounds to the frame, as the screw will resemble a spider with the many wires being its legs. It will be the only wire except for the gauge feed wire off the sending unit, that will come from above the gas tank. The feed should be red IIRC, so it will be the other one... green IIRC.

---If you absolutely had to, taking down the gas tank is not that big of a deal. Safety glasses, a deep well socket, a piece of 12" x 18" plywood to place between the floor jack and gas tank, a regular screwdriver to undo the hose clamps, some new fuel filler hose & vent hose (same material as the fuel filler hose, not regular fuel of vacuum line). I'd use an electric fuel pump to drain it, but I have done it with 1/2 tank and 3/4 tank when I had to. It's not like it's a POChitvy or something where it's easier to remove the bed. Two J bolts with 9/16" or 1/2" (I forget) nuts, between the tank & rear frame end cap. It will be hard to get it apart if someone used WD-40 though... lol. Apply brake fluid, PB Blaster, Kroil, vinegar/water, ATF/acetone, Diesel/MMO, whatever you know works well as a penetrating oil and let it soak in for a few if the J bolts are rusty. A thin wire brush the size of a toothbrush would help remove rust scale that will get trapped in the threads, then apply some antiseize with teflon down the length of the bolt and start backing the nuts off. About 300 turns of the ratchet and you can jack the tank up with floor jack & plywood and finish removing the J bolts. Once they're done, you can undo the back of the tank straps if you want, but I always left them there. Lift the tank one side at a time and pull the strap out of the way and under the front* of the tank. Undo the filler hose, remove the inspection panel & unbolt the bracket for the filler tube. That being lose now*, not earlier, will make installation easier. Don't reuse the J-bolts unless they're fairly new. Threaded rod will work, no need for new bolts unless you want them. Heat the rod prior to bending and use the old j-bolt as a working model for length, bends, etc. and put all bends in it if you don't want the frame stealing your socket after the socket walks up past the end cap. Those bends are there for a reason... if they're actually IH fuel tank mounting J-bolts and someone didn't replace them with something close.. Apply anti-seize to the new bolts.

---If you've never repaired that ground, I would grab my safety glasses (safety first) and try to remove the grounding screw the usual way. Then with some diagonal cutters, lop the terminals off every ground there & crimp new ring terminals on each wire, apply dielectric grease to each new terminal and mount them to the frame with a new sheet metal screw.

---If you couldn't get the screw out the usual way (safety glasses again), using a sharp chisel, knock the head off the grounding screw. Then punch the remainder of the screw's shank through the frame and screw in a new self tapping screw. Then remove the screw, load it with the new, dielec-greased ring terminals and mount them to the frame.

---Make sure the frame ground to the battery is in good condition as well.

[TBAKPhi22]

This happened to me about 6 months ago. Passenger side tank read empty after I filled it up after about 2 weeks of being empty. I knew the gauge worked, because it read fine for the driver side tank. Dropped the tank and the float was filled with gas. Why it happened all of a sudden? Who knows. Worked good for years before that. I wish it happened in my '67, because they actually had the foresight to put an access hole under the seat! Would have made it a lot easier!

[lightningflash]

Originally Posted by Thomas

--The ground at the frame would be what I'd suspect first (especially since you're in the Great Lakes Salt Belt [lovely winter road treatments] and in Michigan), where cancered vehicles will never be a thing of the past. The grounding screw is pretty much behind the right rear tire no matter which of the two areas it's in. It will either be on the inside of the frame pretty much below the right side, rear marker light or it will be on the inside of the rear, frame end cap, pretty much below and between the tail light & license plate light. You won't be able to miss it once you locate the common screw that holds rear grounds to the frame, as the screw will resemble a spider with the many wires being its legs. It will be the only wire except for the gauge feed wire off the sending unit, that will come from above the gas tank. The feed should be red IIRC, so it will be the other one... green IIRC.

---If you absolutely had to, taking down the gas tank is not that big of a deal. Safety glasses, a deep well socket, a piece of 12" x 18" plywood to place between the floor jack and gas tank, a regular screwdriver to undo the hose clamps, some new fuel filler hose & vent hose (same material as the fuel filler hose, not regular fuel of vacuum line). I'd use an electric fuel pump to drain it, but I have done it with 1/2 tank and 3/4 tank when I had to. It's not like it's a POChitvy or something where it's easier to remove the bed. Two J bolts with 9/16" or 1/2" (I forget) nuts, between the tank & rear frame end cap. It will be hard to get it apart if someone used WD-40 though... lol. Apply brake fluid, PB Blaster, Kroil, vinegar/water, ATF/acetone, Diesel/MMO, whatever you know works well as a penetrating oil and let it soak in for a few if the J bolts are rusty. A thin wire brush the size of a toothbrush would help remove rust scale that will get trapped in the threads, then apply some antiseize with teflon down the length of the bolt and start backing the nuts off. About 300 turns of the ratchet and you can jack the tank up with floor jack & plywood and finish removing the J bolts. Once they're done, you can undo the back of the tank straps if you want, but I always left them there. Lift the tank one side at a time and pull the strap out of the way and under the front* of the tank. Undo the filler hose, remove the inspection panel & unbolt the bracket for the filler tube. That being lose now*, not earlier, will make installation easier. Don't reuse the J-bolts unless they're fairly new. Threaded rod will work, no need for new bolts unless you want them. Heat the rod prior to bending and use the old j-bolt as a working model for length, bends, etc. and put all bends in it if you don't want the frame stealing your socket after the socket walks up past the end cap. Those bends are there for a reason... if they're actually IH fuel tank mounting J-bolts and someone didn't replace them with something close.. Apply anti-seize to the new bolts.

---If you've never repaired that ground, I would grab my safety glasses (safety first) and try to remove the grounding screw the usual way. Then with some diagonal cutters, lop the terminals off every ground there & crimp new ring terminals on each wire, apply dielectric grease to each new terminal and mount them to the frame with a new sheet metal screw.

---If you couldn't get the screw out the usual way (safety glasses again), using a sharp chisel, knock the head off the grounding screw. Then punch the remainder of the screw's shank through the frame and screw in a new self tapping screw. Then remove the screw, load it with the new, dielec-greased ring terminals and mount them to the frame.

---Make sure the frame ground to the battery is in good condition as well.

Thanks for all the info, I will be sure to check the ground.

[bdgn01]

Originally Posted by Thomas

--The ground at the frame would be what I'd suspect first...

Once again, thanks for great information, Thomas. This operation is in my immediate future as well.

[Eric VanBuren]

Unless you like messing with and replacing the ground don't cut the factory terminal off and crimp on a temporary terminal it is not a question of if it will fail it's a question of when it will fail and back there under the truck it will fail sooner rather than later. Since the tank also grounds through the straps a bad ground causing this problem is very unlikely so do the check I detailed first and then report the results. As Scoutboy aluded to I've talked or is the typed many members through getting their gauges properly functioning again including verifying that they are in calibration.