Can You Adjust the scale on the Fuel Gauge?

[TomoHawk]

I fugured out that te scale on my Gas gauge is about 1/4 tank high, so I usually run out when the gauge reads 1/4 full. I cleaned the connector for the fuel-level sender last summer, which is when It started reading off. I also cleaned the connector at the gauge about the same time. So either I need to clean the connector and the connections on the sender itself, or the gauge itself needs to be adjusted.

thx

[AZ-240z]

Hello Tomohawk,

This is just speculation on my part, but the fuel gage sending unit is no more than a float suspended in the fuel tank. I would take a look at this first, to see if it moves freely, is not binding, or possible leaking fuel into the float, itself.

The float is mounted on the end of a long wire rod, or arm and could possibly be calibrated by bending the arm slightly to adjust the signal in the sender, itself.

I haven't done this, myself, but this might be a possible fix. The tank would have to be drained, then refilled with a known quantity of gas not to exceed the height of the port where the sending unit is mounted, say, a quarter of a tank. Then, remove the sending unit and make incremental adjustments to the arm until the gage reads 1/4.

Again, as a disclaimer, I have not done this, and am just offering an idea which may, or may not, have any merit.

Dan

[dhoneycutt]

I fugured out that te scale on my Gas gauge is about 1/4 tank high, so I usually run out when the gauge reads 1/4 full... thx

I also have this problem except when my gauge reads "E" I actually have several gallons left in my tank. What irritates me is my sending unit is brand new!!! If you try AZ-240z suggestion, please post results so that I may try it too. (I just don't want to be the tester on thisLOL LOL )

[peng155]

You might have a look at the write up at the link below... Not sure if it'll help but it might be a place to start...

http://alteredz.com/gagecalibration.htm

I fortunetly haven't had any problems with any of my gages, so I can't give ya any first hand advice... But it looks like you may need to either service, adjust, or calibrate your sending unit...

[TomoHawk]

I wasw hoping to havethe gas tank reconditionedthis summer, and the sender would be done along with it. But it looks like the car will need the tank attached. It seems a mental re-scaling will do for now.

thx guys

[peng155]

If I may offer my thoughts... beg, borrow, buy a sending unit that is know to be in working condition, and measure the resistance at the full, position, and at the empty postion...

When you pull your tank you'll need to remove your sending unit anyways.. at that time check your units measurement against the working one..

Just from reading the write up I'll assume that the resistance will need to be increased to get your fuel gage calibrate to read empty. Only problem is that you'll need to calibrate the sender to the fuel gage that is in the car, and you may need to take in to consdieration the car sending unit wiring since the sending unit, and gage operate on resistance.

Again I am assuming that the wiring shouldn't make a huge difference, but in a 30 year old car you never know...

[Bonzi Lon]

Another thought: These were calibrated at the factory on new springs, suspension, so they sat level, the bottom of the tank where the float sits is at an angle. The tank itself appears level. Any slight shift in levelness could affect the reading. If over the years the springs have sagged or different tire size front to rear, or just that squat they seem to have, or even if the tank has shifted (I doubt) or been dented there? Or, is something keeping the float from falling further than 1/4 full? Just pitching anything.

I have just removed my tank to line the inside and the float unit is a ball of rust. New one has been ordered. The arm is rather long (the longer the travel the closer to tolerance you can get) and appears to be easily bent to calibrate.

Or you can put a Post-it note on the guage, "Quarter tank will get me nowhere!"

[Duffman]

Going to piggy-back on this old thread. Have issues with fuel gauge reflecting a full tank at no more than 3/4 level and empty tank at no less than 1/4 full (short range!). Have new fuel sending unit and had this issue with prior fuel sending unit as well. Any thoughts to adjustments on the fuel sending unit to increase the range? Is this a fuel gauge issue? Most posts I have read talk about reading too high or too low, but mine registers in between! Any thoughts?

Edited October 27, 2011 by duffman

[beermanpete]

The gauges have calibration adjustments. There are small holes in the case to access the trim adjustment using a flat blade screwdriver.

The tank sender can be adjusted by bending the arm that holds the float.

[Duffman]

Thanks, Pete, will check the back of the fuel gauge and see if there is a way to adjust it. Bending the arm on the fuel sender won't help me in both directions (more full or more empty), just one way or the other. Need to show full when full and empty when empty!

[5thhorsemann]

Are you sure the tank is empty when you are showing 1/4 tank? Its not likely that the calibration is that far out at the gauge. If you are sure the tank is empty, add like 7 gallons of gas and see if the gauge reads 3/4 tank. If it does, bend the rod to evevate the float till the gauge reads a half tank and you should be good.

[Duffman]

Yes, Mike, have run out of gas with the gauge showing just under 1/4 full reading on gauge. When I fill it up it goes to just above 3/4 full on the gauge.