2g GSX speedo reads too high, fuel indicator not working

[mhuffman]

My friend just got a '95 GSX. I noticed his speedo reads about 10mph high consistantly. He is running 215/55-R16 combo. Also, his fuel gauge is stuck below E and doesnt move, even after a complete fill up.

I havent check his fuel level sending unit/connections yet.

has anyone had these problems before?

 

[99gst_racer]

I'm having this same probem with my fuel level gauge.
In my case, I'm almost positive my wiring is correct.

Does anyone know how to test a sending unit for functionability?

 

[twinturbo3k]

The only way I could think to check the unit would be to literally pull the unit out of the tank a lift the float lever up and down. The problem with that is that the car would be on, and the pump would be out of the fuel and spinning freely- not a good thing.

I would check your float.

I have no real input on the speedometer problem, I would attribute it to aftermarket wheels but if it is 10 mph all the time that wouldnt make sense, since it would be correlating to the current speed of the vehicle.

 

[mhuffman]

The only way I could think to check the unit would be to literally pull the unit out of the tank a lift the float lever up and down. The problem with that is that the car would be on, and the pump would be out of the fuel and spinning freely- not a good thing.

I would check your float.

I have no real input on the speedometer problem, I would attribute it to aftermarket wheels but if it is 10 mph all the time that wouldnt make sense, since it would be correlating to the current speed of the vehicle.

He ditched the 17" GSX wheels in favor of the 2g GS/GST 16" wheels. the OD is quite similar, which means the error is coming from somewhere else... WTF

 

[99gst_racer]

He ditched the 17" GSX wheels in favor of the 2g GS/GST 16" wheels. the OD is quite similar, which means the error is coming from somewhere else... WTF

A smaller overall diameter of a wheel and tire combination will cause a higher reading, not a lower one.

 

[mhuffman]

The fuel gauge isnt working because the fuel level sending unit is bad.

 

[99gst_racer]

The fuel gauge isnt working because the fuel level sending unit is bad.

How did you test to find out it was bad?

 

[mhuffman]

How did you test to find out it was bad?

Here's a brief explanation of your gas gauge.
A float in the tank sends a signal to the gauge by varying the resistance of the fuel level unit. High gas level means low resistance, and the gas needle is at full. low gas level means high resistance, and the needle goes to empty. When there is a fault in the level unit, it typically becomes infinite resistance, making the needle go all the way down.

SO,

i pulled up the back seat cushion and disconnected the fuel level sending unit connector.

Then, i used a short piece of small gauge wire to short circuit each of the terminals of the connector to the chassis (or any other good ground) one by one.

One of the fuel level connector sockets (when short circuited to ground) made the gas gauge needle go all the way up. This meant that the wiring to the level unit had continuity, and the gauge was functioning properly. By process of elimination, the fuel level unit is bad since the gauge, wiring, and connector are all good.

That is how i determined the level sending unit was at fault.