Fuel level problem with analog tach combo gauge

[sdlsaginaw]

I need to diagnose which part is failing, gauge or sensor. The low fuel light comes on fine around .8 gallons. The level indicator however never displays less than 1/2 tank.

Originally the gauge wouldn't give a tank size option. Back then it did display 1/4 tank but never range. Eventually it gave me the option and I set it to 4.5 gallons. Not sure if its read under 1/2 since.   Range displays, but gets unrealistic as the tank gets lower.

One other oddity, randomly the gauge returns itself to odometer from whatever value I had it displaying.

The gauge and sensor were both purchased from Surdyke in January/February. I would think they would be under warranty.  Am I going to have to pay my local dealer to work on this to get the failed part identified and replaced?

This is on a 2009 1200 Custom.

[WhipLash96]

It sounds like the sending unit to me.

[sdlsaginaw]

I hope so, after messing around with it last night I ended up ordering a new one from Newcastle.  It was going to cost that much or more for the dealer to mess with it anyway.

I siphoned the tank empty, indicates 1/2 full.  Pulled the ground plug, eventually got low fuel light and no bars.  Plugged connector back in, after several seconds low fuel light went off and back to 1/2 tank.

[wholehog]

following is in regard to big twin but may also apply to sportster......


June 21, 2004
Low Fuel Lamp On EFI Models
Information on low fuel lamp diagnostics was inadvertently omitted from the 2004
Manuals. The low fuel lamp should turn on when the fuel level is between .7 and 1.3
gallons. Whenever checking proper lamp ON-OFF operation remember all of our EFI
model fuel gauges have a software filter that limits the lamp reaction when the ignition is
ON. This prevents lamp flicker under hard acceleration and braking. Each time the rider
turns on the ignition switch the software filter is reset to the current fuel level value.
When diagnosing a fuel lamp issue the float must be positioned while the ignition is
OFF. When ignition is turned ON, proper light response can be verified. If the low fuel
lamp is lit, and the float is raised either manually or by refilling the fuel tank while the
ignition switch is ON, the light will not go out for quite some time. Simply turn the ignition
switch OFF-ON to reset.
Similarly, if there is enough fuel for the low fuel lamp to be extinguished and the float is
either bottomed manually or the tank is drained with ignition ON, the lamp will not light
for quite some time. Simply turn the ignition switch OFF-ON to reset.

[sdlsaginaw]

Well, that was a waste of $122. I replaced the sensor tonight. Not only did it go straight to 1/2 tank with the first gallon I put in, it's staying at 1/2 tank now that its full even with several power cycles.

I'll ride it tomorrow and see if anything changes, but so far it's worse.

Another question: anyone know what holding the button in on the range is supposed to activate/reset?  After 5 seconds the display blinks once. Hold it in again, it blinks twice. Alternates between 1 and 2 blinks. Can't find that documented anywhere.

[WhipLash96]

I guess after all of this I guess I would do this..... I would throw away that stupid gas gauge!!!!! They do not belong on a Sportster anyways! Take your bike out for a ride starting with a full tank of gas, write down what your mileage is, go for a ride, after say about 60 miles, refuel, then do some math and figure what your gas mileage is. I pay real close attention to what kind of miles I put on when I am on my Sportster and I have a 4 gallon tank on mine! that easy and better than dealing with that crap. JMO