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Erratic fuel gauge reading troubleshoot

Posted: Fri Nov 15, 2019 9:37 am
by airlinepilot
I experienced the following trouble lately, here’s my solution for you. After fueling the fuel tank to its max capacity, i had a 3/4 reading on the gauge and only 384km to empty on the Dashboard.
I knew something was wrong.

I took off both fuel modules access pannels and removed the electric connectors. I plugged in my multimeter on the 2 terminals for the fuel level sender unit. (2 wires on driver side, can’t go wrong) (2 wires on pax side where the terminal is larger, there is 4 terminals).

The reading on the driver’s side was around 15ohms, which is perfect when the tank is full. If the tank would have been almost empty, a reading of 180ohms would have been fine.

On the passenger side, the reading was in the vicinity of 60ohms, VOILÀ! There was the fault.

Now, the fault is mostly caused because of ethanol and sulfur content in the fuel. I buy 95% of my fuel at my local COSTCO. It is good quality fuel but still contains these additives in the regular 87 octane fuel.

I decided not to open the fuel tank but just to use a RISLONE complete fuel treatment. I was hopping that it would clean just enough the fuel sender unit and erase the fault. Chevron would have been my first choice but it is not sold anywhere in the Montreal area.

After less then 30km of driving, the fault is gone and everything is back to normal.

So hopefully, if you are experiencing erratic fuel readings, get out your multimeter in the 200ohms scale, get yourself a 13mm wrench and find for yourself within less then 30 minutes what is causing your issue.

I hope it helps some of you guys.

Re: Erratic fuel gauge reading troubleshoot

Posted: Sun Nov 17, 2019 6:20 am
by airlinepilot
**The sulphur and the ethanol contained in the fuel leaves a thin film of deposits on the fuel sending units and prevents an accurate reading. This is why a good fuel cleaner comes in handy and removes that film. Otherwise i rarely use these kind of cleaning products.**