Topic

This morning when I got in my MGF, the fuel guage was reading about 40% full before I turned on the ignition. Can I safely assume that the guage has ceased to function? I should add that I subsequently filled the tank to fuel pump cut off and the guage still appears to read the same. Any advice would be appreciated including whether I can check the fuel sender reading without removing it from the tank. Many thanks...

check the wiring on the n/s of the boot just under the boot hinge this is where I found my fault , a broken wire , common fault.

The fuel gauge reads even when ignition is turned off, so seeing a half full (or half empty depending on your outlook on life is not a concern.

However if you have "brimmed" the tank, and it still only shows half full (or empty) then there is a problem.

Any electrical fault at the rear can be caused by the wiring at the boot hinge, so always worth a check as Graham has indicated. Cut back the plastic cover and inspect carefully.

To test the wiring/gauge you need to disconnect the wiring to the sender, and short the sender wire to ground. It should move 100% one direction (cant remember which way) and when disconnected it should go 100% the other direction.

If it does this then the wiring and gauge are OK and the fault is the sender unit.

Alternatively you could remove the pump/sender assembly from the tank, and move the float by hand and see if there is full movement of the gauge.

One fault I have had was with the wiper arm that presses against the windings in the tank was loose, which caused an always "mid position reading". Just gently bending the wiper to the windings to make better contact fixed it.

Peter

Mine's been stuck on full for the last few days! So I'll be testing as described at the weekend...

tnx for the advice

Nick

G0RSQ wrote: wrote:

The fuel gauge reads even when ignition is turned off, so seeing a half full (or half empty depending on your outlook on life is not a concern.

However if you have "brimmed" the tank, and it still only shows half full (or empty) then there is a problem.

Any electrical fault at the rear can be caused by the wiring at the boot hinge, so always worth a check as Graham has indicated. Cut back the plastic cover and inspect carefully.

To test the wiring/gauge you need to disconnect the wiring to the sender, and short the sender wire to ground. It should move 100% one direction (cant remember which way) and when disconnected it should go 100% the other direction.

If it does this then the wiring and gauge are OK and the fault is the sender unit.

Alternatively you could remove the pump/sender assembly from the tank, and move the float by hand and see if there is full movement of the gauge.

One fault I have had was with the wiper arm that presses against the windings in the tank was loose, which caused an always "mid position reading". Just gently bending the wiper to the windings to make better contact fixed it.

Peter

Just to clarify, some MGFs have fuel gauges that return to zero on ignition off. This causes endless confusion because both systems are in place. So, just be worried if the needle never moves even after 100 miles or so.k My MK2 F is a returns to zero type.

Getting the fuel pump and sender unit out is 'fun', but nowhere near the joy of getting it back in with the seal in the correct position. Otherwise get ready for a cabin full of petrol fumes!

Worth checking the connections to the negative earth stud in the boot (on the right hand side in the engine bay).
My ABS was not working when I bought my car, but the dealer refused to believe me saying the light would come on if there was a fault.
I even took them for a drive and locked the wheels up while braking and they were still in denial!
It turned out to be a broken wire at the earth stud. I repaired the connection and ABS was fine.
A lot of equipment is fed from here and it takes seconds to check the wiring is ok.

Sundance