10 replies to this topic

[Stitch306]

The fuel gauge has had a mind of it's own since I got the car back in November. I've recently fitted a new sender thinking that was the problem, no joy. Today I fitted new nippon clocks and there's some life in it now but it only goes to just above half way. I know there's more fuel than that in the tank because I brimmed it this morning! I only drove it from outside the house into the garage after fitting the clocks, does it take time to creep up to the top?

[MGBailey007]

they normally slowly creep up but wont take more than a few mins

[dklawson]

It does take time for the gauge needle to climb to full but the time is measured in minutes, not hours.

As a quick test of the new components, turn the ignition switch to the run position. Bridge the two spade lugs on the sending unit using a paperclip or similar. You need metal to metal contact of the two wires. Over a minute or two the fuel gauge should go to full. If it does, there is some issue with the sending unit. This could be binding of the float arm because the unit is not installed correctly or perhaps it is the wrong sending unit. Another possibility is that the sending unit float has a hole in it allowing it to fill partially with gasoline. A partially full float will typically cause the gauge to indicate low as the float will not rise all the way to the top.

[matt615]

Does your car have the original fuel tank fitted? If it's had a later fuel tank fitted that could explain this problem.

The later fuel tanks from 1993 ish onwards have a bracket in for the injection fuel pump. They use a slightly different shape sender unit, to avoid fouling on this pump bracket. If you fit an older type sender unit to one of these tanks, it will get stuck half way up and the gauge will never read more than about half full.

I know your car is a 1988, but there is a possibility someone has fitted one of these later tanks to it.

Edited by matt615, 08 March 2012 - 07:25 PM.

[Stitch306]

Thanks for the info, I wasn't aware of the different fuel tanks, Is there any way to be sure which I've got? Any external differences between them?

[matt615]

When you take off the fuel cap, is there a big gaping hole, or is it blanked off with a small flap that you have to push the petrol pump in to?

If the latter, then it's one of the newer tanks.

Hope that makes sense.

[matt615]

Also you could try removing the sender unit, and pushing it up to the full position with it out of the tank. If this makes the fuel gauge go to full, then it proves the sender unit is working properly, but getting caught on something inside the tank.

[Stitch306]

Yeah, makes sense. Just been looking at tanks on minispares hoping I could see a difference. Mines got a gaping hole, not the unleaded fuel neck. Cheers for the info :)

[Stitch306]

Gonna have to drive about for a bit before I mess with the sender again. Last time I did it I thought the fuel level should be below it, knocked the locking ring around and got petrol all over my hands and had to try hold the sender in place while I got the locking ring back on :)

[matt615]

Ok, well you could do as dklawson suggests. Disconnect the two wires from the sender unit and join them together. This should make the fuel gauge go to full. If it does it will prove that the fuel gauge is working properly, and there is something wrong with the sender.

[Stitch306]

Hmmm... Strange goings on. Used a paper clip on the fuel sender contacts and it shot to the top, took the paper clip off, used it to ground the temp sensor, the fuel gauge went to the top and the temp only went 1/2 way, gave it a tap on the face and that went to the top. Could it be a case of sticky needles in the gauges? I bought the clocks from eBay, the seller said he was having a clear out of his garage. If they've been sat unused for a while could that make them stick?