R33 GTST S1.5 Fuel Gauge Issues

[tsirtsa]

Hey guys, have searched the internet all over and no one else has posted about this issue I'm having so here it goes. My fuel gauge was reading quarter full when it was actually empty, had a few other issues too and decided to swap to the proper ecu (had a nistune z32 ecu which came in the car) and now not only has the issue remained but it's actually gotten worse now reading half full when the gauge is 0. Anyone got any clue how to fix this? 

[GTSBoy]

The ECU has nothing to do with the fuel gauge. Any observations you have made as a result of changing the ECU are meaningless and just coincidence.

There is a variable resistor attached to a float in the fuel tank. The float sits near the bottom on an empty tank and floats up to the top on a full tank, dragging the contact up and down the variable resistor with it. If there is gunk on the resistor it can interfere with conductivity or it can jam the movement of the float (ie so that it hangs up at 25% instead of continuing to fall below that towards the bottom). It can also be a wiring problem caused by hamfisted fuel pump upgrades, or a mechanical problem caused by hamfisted fuel pump upgrades (ie, the hanging of a new fuel pump so that it interferes with the movement of the float). And the list of possible causes probably has a few other things that I can't be bothered to try to invent right now, but will likely have been experienced by others.

Take the sender out and inspect.

[tsirtsa]

2 minutes ago, GTSBoy said:

The ECU has nothing to do with the fuel gauge. Any observations you have made as a result of changing the ECU are meaningless and just coincidence.

There is a variable resistor attached to a float in the fuel tank. The float sits near the bottom on an empty tank and floats up to the top on a full tank, dragging the contact up and down the variable resistor with it. If there is gunk on the resistor it can interfere with conductivity or it can jam the movement of the float (ie so that it hangs up at 25% instead of continuing to fall below that towards the bottom). It can also be a wiring problem caused by hamfisted fuel pump upgrades, or a mechanical problem caused by hamfisted fuel pump upgrades (ie, the hanging of a new fuel pump so that it interferes with the movement of the float). And the list of possible causes probably has a few other things that I can't be bothered to try to invent right now, but will likely have been experienced by others.

Take the sender out and inspect.

Absolute legend, if I have time tonight she'll come out and will sus out if someone along the road has hamfisted anything to do with the pump. If the resistor is all gunked up how would you recommend cleaning it?

[GTSBoy]

3 minutes ago, tsirtsa said:

If the resistor is all gunked up how would you recommend cleaning it?

Scratchy scratchy with something sharp/pointy, and some contact cleaner/carby cleaner/degreaser/something.

[tsirtsa]

1 minute ago, GTSBoy said:

Scratchy scratchy with something sharp/pointy, and some contact cleaner/carby cleaner/degreaser/something.

Perfect, will be back to update once the deed is done.

[Duncan]

I'd go nylon brush (toothbrush would suit) and brake cleaner