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2G Inaccurate fuel gauge, intermittent low fuel light coming on

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Kyle_T

15+ Year Contributor
795
12
Oct 19, 2008
Muskego, Wisconsin
My fuel gauge on my GSX has always seemed to read slightly low, but it never bothered me that much. Recently it has been reading over 1/4 low and inaccurate. I had completely filled my tank it it read under 3/4. Then I ran my tank almost dry(swap to e85) and the needle was way under empty. I put 10 gallons in and it only reads 1/4 tank now.

Also my low fuel light will randomly turn on and go off, even when the tank is above half full. But it does seem to still work when the tank is low.

I have pulled both fuel level sending units and inspected them, tried switching it out with another unit with no luck. Made sure the float is not hanging up on anything. Is there a way to test these? Maybe I have a wiring issue somewhere?
 
I'd say check your fuel sending units you have 2 of those. Just like having the fuel injectors cleaned occasionally for maintaining maximum flow the sending units should be on that list to clean when running e85.
 
First clean the ground connections at the tank which may be your whole problem. Then test the resistance of both senders (wires) when unplugged. Drivers side should read between 2 (full) and 50 (empty) ohms. Passenger side should read between 2 (full) and 57 (empty) ohms. They are wired in series to the gauge.
 
I'd say check your fuel sending units you have 2 of those. Just like having the fuel injectors cleaned occasionally for maintaining maximum flow the sending units should be on that list to clean when running e85.

I had just checked both of them a week ago.

First clean the ground connections at the tank which may be your whole problem. Then test the resistance of both senders (wires) when unplugged. Drivers side should read between 2 (full) and 50 (empty) ohms. Passenger side should read between 2 (full) and 57 (empty) ohms. They are wired in series to the gauge.

Do the fuel level sending units use the same ground as the fuel pump? I added a new fuel pump ground when I rewired my pump, but it didn't change anything with the fuel gauge. Which ground connections at the tank, its plastic? Do the fuel senders ground to the chassis some where else?
 
Is there an update for this? I had a very similar problem with my spyder, but will be doing the awd swap next month. While removing the fuel tank from my donor gsx, I didnt remove any grounding wires at all. Only disconnected the connectors. I tested resistance on my fuel sender and it was faulty, but also the metal fwd tank was badly dented in when I bought the car, which I had always assumed was the main problem.
 
The ground wire connection to the chassis for the fuel pump, fuel level gauge sender, and low fuel light sender are all at the same point which is the "front floor upper cross member (left side)" which I think is under the driver's seat. Check that connection for corrosion, looseness, broken, etc.
 
I'm pretty sure it was a loose connection in the connector on top of the fuel pump hanger. Although the gauge still never reads 100% full. I can deal with it. As long as it works.
 
Although the gauge still never reads 100% full. I can deal with it. As long as it works.
As a test ground the all yellow (may be faded) wire on the driver's side sender connector. Dash gauge should read full when key on (will move very slow). If not, the gauge is bad or you have resistance in some connector on the way to the gauge.
 
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