fuel gauge question

[wifegonnakillme]

I'm down to the tinkering stage with my 3 -

My gauge does move around, I can fill it up and get a full reading, occasionally at or around half it reads half and sometimes, even though it is not empty, I get an empty reading - however it is not reliable and does not graduate smoothly from full to empty. Do you folks think that this is a problem with the float? I haven't observed it sinking below the level of the fuel, so I tend to think it is holding air. One possibility is that it is just not moving as freely as it should...

Wiring connections should be good with the new harness.

I could pull the tank (and eventually I will have to as there is a small leak at the top by the sender), but I would rather have a better idea of where to look before I take that on...

thoughts appreciated,
Kerry

 

[NickMorgan]

You can use a bit of hooked wire to move the float up and down through the filler opening. You can then watch the gauge, with the ignition on while the float is moved through its full range. Most likely it will be the sender unit that is faulty. It was on mine, but i only discovered after replacing the gauge!!

 

[guzzul]

I assume you have tried grounding the sender wire a couple of times to see how the gauge reacts. If it goes to full smoothly then the gauge is probably fine.

I'm not sure if the 3 uses a voltage stabilizer or not, but that is another source of problems. If your other gauges are working properly (notably temperature) then the stabilizer is probably ok.

You might check to make sure the fuel tank sender ground is not intermittent or corroded, which might cause variable results too.

If the problem is either the sender or the float you are going to have to pull the sender anyway.

 

[MGTF1250Dave]

Aloha Kerry,

The fuel gauge sending unit can be checked as Nick suggested. If you remove rear bulkhead panel you have clear access to the top of the tank. Guzzul lists the basic electrical test that I would recommend. If the gauge reacts well to those tests, the sending unit can be then be removed with out taking the tank out of the car or the added hassle of draining it. With the sending unit in hand you can easily move the float and see how the gauge reacts.

 

[PSUTR3B]

My guage is rather slow going from full to 1/2 but declines over fewer miles (ie. faster) from 1/2 toward empty. The last quarter can go in a fairly short distance. It certainly does not go down at a constant rate. From others I have talked to, this is not completely unusual. The empty reading when it is not could be a grounding issue.
Gary

 

[BIBBER]

Likewise I have not been able to rely on my fuel gauge...I elected to use the NOS version a stick....

 

[philman]

i had a problem with the fuel guage on my mgb-gt. guage was fine, when I replaced the sending unit i found the float was fouled by one of those silly springs that people put in the filler neck to prevent gas siphoning. sending units aren't usually very expensive or hard to replace. for peace of mind i replaced mine even after i fixed the problem.

 

[wifegonnakillme]

thanks folks - will try and find some time to play with it this weekend and update,
cheers,
Kerry