bob duffer Posted May 28, 2015 Share Posted May 28, 2015 My fuel gauge is pegged in full all the time . Is there something i can check to see why or do i have to pull the tank down? Thanks Link to comment Share on other sites More sharing options...
misterc9 Posted May 28, 2015 Share Posted May 28, 2015 What kind of car is it? Link to comment Share on other sites More sharing options...
56buickinga Posted May 28, 2015 Share Posted May 28, 2015 Had this issue with my 72 skylark. There are a few things to check. Year make and model would be helpful.http://www.chevyclassicsclub.com/the-gm-fuel-gauge-mystery-1965-newer/I know it's 65 or newer but gives a good bit of insight.Did this occur recently or has this been a problem since you have owned the car?My car read past full, it was a bad sending unit.But I was able to check by disconnecting the fuel sending unit wire in the trunk and grounding it out the needle dropped to E and I knew the tank had to come out.73 chevy truck I had was doing that the fuel sending unit wire was pinched on the trans cross member causing a false reading.I hate dropping the tank of any vehicle but if you do the above checks (with the service specs of your car) and the guage goes to E then you will most likely have to drop the tank to inspect the ground and sending unit. Link to comment Share on other sites More sharing options...
Joe in Canada Posted May 29, 2015 Share Posted May 29, 2015 On most cars if it reads past full it could be a bad ground. Link to comment Share on other sites More sharing options...
whtbaron Posted May 29, 2015 Share Posted May 29, 2015 Also before you get too excited changing components, disconnect the wire at both ends and make sure there is current coming through. It's a lot easier to change out a broken wire than gauges or senders. Link to comment Share on other sites More sharing options...
ply33 Posted May 29, 2015 Share Posted May 29, 2015 What kind of car is it?It does make a difference, some cars in the 30s and 40s had a two wire setup and helpful things like "disconnect the wire at both ends" may be insufficient to debug the problem. Link to comment Share on other sites More sharing options...
28 Chrysler Posted May 29, 2015 Share Posted May 29, 2015 Most cars use a variable resister in the sending unit to ground the gauge.One side of the gauge is "hot" the other side goes to the sending unit.In many incidents when to gauge goes to full the wire to the sending unit has been shorted to ground.Your gauge may also have an internal short. Link to comment Share on other sites More sharing options...
bob duffer Posted May 29, 2015 Author Share Posted May 29, 2015 What kind of car is it?1934 Buick series 50 Link to comment Share on other sites More sharing options...
Guest AlCapone Posted May 30, 2015 Share Posted May 30, 2015 My new sending unit read full all the time and it was the ground. Wayne Link to comment Share on other sites More sharing options...
bob duffer Posted May 30, 2015 Author Share Posted May 30, 2015 I took out the gauge and would you not think it would go to empty if no power to it? Does this mean i need a new one? Can i even buy a new oneor should i get this one fixed? Link to comment Share on other sites More sharing options...
28 Chrysler Posted May 30, 2015 Share Posted May 30, 2015 I take it you have tried tapping it on the side to see if it is just stuck.Try reversing the polarity and see if the needle moves back to empty.If it moves to empty then reverse the wires again and see if it goes past full or stops at 3/4s again. Link to comment Share on other sites More sharing options...
bob duffer Posted May 30, 2015 Author Share Posted May 30, 2015 When i shake it side to side it moves between full and 3/4. I'm guessing it needs to be re- built. Link to comment Share on other sites More sharing options...
Friartuck Posted June 1, 2015 Share Posted June 1, 2015 Bob, Sounds like the needle movement twisted when the needle went to full. The gauge's needle should rest at EMPTY with no connections to it. Either replace it with a used gauge applicable for your Buick or send it to a gauge repair shop. I know Wolf is one vendor mentioned here in the Forum. More importantly is why the gauge went to full. Looks like the the sending unit has separate connections, one to ground and the other to the gauge. If you have access to a Volt Ohm Meter, use the resistance scale and measure the resistance as you manually move the float from one extreme to the other. Common problems are the metal arm that glides across the winding loses contact at certain spots or the winding itself broke (wore down). PM me if you need more help. Link to comment Share on other sites More sharing options...
Guest MORRISGAUGE Posted July 21, 2015 Share Posted July 21, 2015 It is important to check your wiring before assuming repair, but yes, your gauge appears to require service. I would assume that you are still 6 volt? Also, 9/10 times the sender has issues due to the environment that it is subjected to vs the gauge. Both units need to be well grounded. www.morrisgauge.com Link to comment Share on other sites More sharing options...
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