My 82 fuel gauge reads full when the tank is full, and pegs to the full side when I disconnect the plug at the tank. But - - it only goes down to just above half as I use up fuel, and never any lower. If that's where my gas level stayed, I'd be a happy camper, but we know that's not the case.

I'm trying to determine if it is a stuck gauge, or defective sending unit. What do I have to do (preferrably at the connector by the tank) to send the gauge to the empty side of the scale? That would tell me the gauge is "likely" okay. Wire colors would also help, since there are three plus ground, and two likely are the fuel pump.

It's a lot easier to get the sending unit out of the tank then get the stupid cluster off to get at my gauge. I know because I have been trying to get at my oil pressure gauge, which only reads about 5 psi (mechanical test gauge reads sufficient pressure). OP gauge reads full scale when I disconnect the plug at the sending unit, but I think the resistor is bad (other thread, anyway).

Thanks, Craig

 

Go back to where you disconnected the wire to the tank, and ground it.  The gauge should now read empty.  If it does, the problem is in the sending unit inside the tank, or a bad ground from the sending unit.   If the gauge still only goes to 1/2 you now want to ground the same pink wire at the gauge itself.  If it now goes to empty, the wire between the gauge and the tank has resistance.  The resistance would probably be a bad connection, usually due to corrosion or loose contact at a connector.  If it still only goes to 1/2 when grounded at the gauge, check for 12 volts or better across the other two connectors.  If you have the voltage (with key on) then you have a bad gauge.

[QUOTE=kstyer]Go back to where you disconnected the wire to the tank, and ground it.  The gauge should now read empty.  If it does, the problem is in the sending unit inside the tank, or a bad ground from the sending unit.   If the gauge still only goes to 1/2 you now want to ground the same pink wire at the gauge itself.  If it now goes to empty, the wire between the gauge and the tank has resistance.  The resistance would probably be a bad connection, usually due to corrosion or loose contact at a connector.  If it still only goes to 1/2 when grounded at the gauge, check for 12 volts or better across the other two connectors.  If you have the voltage (with key on) then you have a bad gauge.[/QUOTE]

Headed for the garage now..........................

OK. Poked a pin thru the pink wire and grounded it. The gauge went to E. Perfect. Now I know it's the sending unit. Sometime when I feel adventurous I'll pull it and try to fix the rheostat. I refuse to spend $250 for a new sending unit - I'll keep using my stick/odometer.

Thanks so much. Now off to solve my oil pressure gauge problem. I CAN get that gauge to go full scale, as I noted. I also applied air pressure to the sending unit/switch (actually to the original one and a new one), and got the same 5 psi reading, so I pretty much know it's the gauge/resistor/circuit board. It's just so gawd awful getting it out without breaking something. Oh well. I'll wait for a cool day, when I feel real patient

Thanks again for the assist. This is a great forum.

Remember to seal the wire where you pierced it with the pin.  Other wise corrosion can set in.   On easy way is with the wire clean, put a tiny dab of silicone sealer on the hole.  It works great.

[QUOTE=kstyer]Remember to seal the wire where you pierced it with the pin.  Other wise corrosion can set in.   On easy way is with the wire clean, put a tiny dab of silicone sealer on the hole.  It works great.[/QUOTE]

Yupper. Thanks Ken.  I, being a sailor, have found that some stuff called Star Brite Liquid Electrical Tape works great for keeping moisture out of electrical connections. It's almost like that stuff you can dip your tool handles into to give them insulated grips. I use it anytime I disrupt a covering, find chafe-thru, solder two wires together, etc. Silicone sealer works good, too, but this stuff gets real tough like the covering on the wire, but stays flexible. It dries real fast, too. You can find it at Boat US, West Marine, other marine suppliers. I recommend it be kept in everyone's toolbox.

WOW!  That's excellent technical assistance ... I may have already gotten my money's worth, and I didn't even ask the question.

My CE's fuel gauge is way past full no matter what is in the tank (or not).  I figured it had something to do with the sending unit or ground, now I know enough to go be dangerous!

Mike M

Mike, keep us posted on how your repair goes.  We can help. (I hope).

Mike, would you post the steps you go through and some pictures to replace the sending unit.  My 82CE has a similar problem - gauge is accurate for the first half tank, last half tank it seems to drop at quarter tank increments.  It has improved a bit with gas additive to clean the carb since I initially thought it was sticking because the car sat for soooo many years.   

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Lifetime Member #58
Our 82CE

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[QUOTE=Reds82CE]Mike, would you post the steps you go through and some pictures to replace the sending unit.  My 82CE has a similar problem - gauge is accurate for the first half tank, last half tank it seems to drop at quarter tank increments.  It has improved a bit with gas additive to clean the carb since I initially thought it was sticking because the car sat for soooo many years.   [/QUOTE]

Somewhere I read about something you can add to the gas that will (may) help with cleaning the wiper on the sending unit. Your's sounds like it had the same thing happen to that mine did. It sat for a Long time at a tad over 1/2 tank. Now that is where the gauge stops going down. I once bought a truck that had the same problem, and I used something like an injector/carb cleaner a few times, and kept the tank fuller than the problem point, and it soon corrected itself. I haven't seen one of our 82 units yet, but if it has an exposed wiper (rheostat or variable resistor) it could be burnished up and will likely be ok. If it is sealed, maybe it could be carefully dismantled and fixed. I hope so, because a new on is expensive. The only thing I worry about is getting the three fuel lines off without splitting the rubber. Other than that it should be a piece of cake to get the unit out. I'll take pics, also, as soon as I start. Gotta go to a car show this weekend, so probably next week. Let me know how your's goes, also, Mike.

When (if?) I ever get around to fixing it, I'd be glad to take some pics.  But honestly, it could be a long time before I do fix it.  If I filled the tank and drove it the average of 18 miles per year, the fuel gauge doesn't become a problem for over a decade

So don't wait on me to fix mine, or you might be calling AAA for a tow now and then ... And we wouldn't want that!

One thing you may need to consider is, that tank has a "bladder" in it. They are known to deform over time, and can/will hang the float for the gauge.
The main part of the bladder can be removed if it is damaged, but it is also the seal for the sender unit/tank. You can cut the top part of the bladder off, where it goes around the hole, and use it as the gasket for the sender.
They do not make a gasket for this tank, so you're pretty much stuck with using part of the bladder, or using a thick cork gasket material, and making your own.

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Joel Adams
C3VR Lifetime Member #56    
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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Joel..... I beleive corvette central now carries the gasket for the sending unit, I'm at work and not at home but I just got a gasket from them for the sending unit or I'd give the PN for the gasket. You are right a few years ago you had to make you're own gasket.

Steve.

Thanx for that info, Steve!

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

[QUOTE=Midwest Muscle]

When (if?) I ever get around to fixing it, I'd be glad to take some pics.  But honestly, it could be a long time before I do fix it.  If I filled the tank and drove it the average of 18 miles per year, the fuel gauge doesn't become a problem for over a decade

So don't wait on me to fix mine, or you might be calling AAA for a tow now and then ... And we wouldn't want that!

[/QUOTE]
Mike,
With only original 450 miles, you need to either keep the tank topped off to keep the air out or drain the entire system to keep everything from getting varnished.
But remember, Vettes were built to be driven.

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