Fuel Guage Calibration - Low Fuel Warning

[flint54]

First off, the gauge works. Most folks would say "Good enough, don't mess with it!"

 

However, the low fuel warning light comes on way too soon, i.e., at 1/4 tank. Have 18.5 gal

tank, so that's just under 5 gal. FSM says light should come on at 2 gal.

 

The gauge says full when full, and empty when empty, so the response seems in order.

 

FSM for mine says full = 5 ohms, half = 33 ohms, and empty = 105 ohms. Also says

low light should come on at 66.5 ohms (via a module on the back of the cluster).

Clearly not a linear response.

 

I noticed at the JY that the variable resistor on the sending unit has provisions for

adjustment, but this would only change the output as a function of fluid level and

would affect the overall guage position.

 

I know I should (and will) measure resistance at the various fluid levels, but am puzzled

how I would adjust the LFW only. Don't recall seeing any adjustment on the module,

and FSM is silent.

[summerinmaine]

First off, the gauge works. Most folks would say "Good enough, don't mess with it!"

 

However, the low fuel warning light comes on way too soon, i.e., at 1/4 tank. Have 18.5 gal

tank, so that's just under 5 gal. FSM says light should come on at 2 gal.

 

The gauge says full when full, and empty when empty, so the response seems in order.

 

FSM for mine says full = 5 ohms, half = 33 ohms, and empty = 105 ohms. Also says

low light should come on at 66.5 ohms (via a module on the back of the cluster).

Clearly not a linear response.

 

I noticed at the JY that the variable resistor on the sending unit has provisions for

adjustment, but this would only change the output as a function of fluid level and

would affect the overall guage position.

 

I know I should (and will) measure resistance at the various fluid levels, but am puzzled

how I would adjust the LFW only. Don't recall seeing any adjustment on the module,

and FSM is silent.

 

I asked this very question not too far back, and there was a suggestion that you could simply fit a resistor into the LFW circuit. Determine what the resistance is at 2 gallons, and add as necessary to "trick" the gauge module. That's the theory anyway. I just decided to live with it.