gas guage

[bbs1980xs1100g]

my gas guage started to misread by 3/8 a tank.( full tank registers 5/8 tank) and the guage works back down to empty but misreads by 3/8. This started the same day the dealer had it up on the lift, for new front tire, could they of messed it up with the lift ? or is the floats bad? sensor problem any ideas anyone? thanks brian

[sixtysix]

There is a test in the book to determine the problem, when my gas gauge went bad, it was the regulator inside the tach. It has to put out 7 volts or something. I was just driving along and the gage started going up, not down.......it worked, sort of, but only in the top half of the gage....a new fuel gage regulator solved the problem. If I think of it I will grab the book and outline the test for you.......

[Wayne]

I have had a similar problem with mine since I bought it from my dad over 5 years ago. Never bothered to fix it but would like to. If you could post the info to do the fix I'd appreciated it Gary.

[bbs1980xs1100g]

ok more clues. i filled up and it only registered 5/8tnk, ran perfect, then 125 miles later the bike stopps running, gauge reads E but there is only 125 miles used from a full tank , so i added3 gallons and the tank reads 1/4tank and runs good again, the guage is off by 1\2 tank. Is there a censor shutting down the bike when the gas guage reads E even though their is 1/2 tank of gas? floats or what ? now ive got 7/8tank and it registeres 1/4 tank runs fine until 125 miles then quits, thanks brian

[skids]

The test of the voltage from the meter and the test of the resistances (full and empty position of float) will not tell you whether or not the needle deflector is broken. Because of the inconsistent readings, that is what I suspect the problem is. There is a bimetallic tyne that is wrapped with wire. The greater the current, the hotter it gets, and the more it deflects. I suspect that with repeated bending, they snap at the base. You can monkey with it, but for all of the trouble it is better IMHO to buy another used tachometer/fuel gage unit.

Originally posted by bbs1980xs1100g
ok more clues. i filled up and it only registered 5/8tnk, ran perfect, then 125 miles later the bike stopps running, gauge reads E but there is only 125 miles used from a full tank , so i added3 gallons and the tank reads 1/4tank and runs good again, the guage is off by 1\2 tank. Is there a censor shutting down the bike when the gas guage reads E even though their is 1/2 tank of gas? floats or what ? now ive got 7/8tank and it registeres 1/4 tank runs fine until 125 miles then quits, thanks brian

[bbs1980xs1100g]

the bike runs fine with a full tank. then 125 miles later it quits. the last 5 miles sounds like it is boggling down, then i fill up again and it is fine again, Does the needle showing E have a auto shut off electronically?

[sixtysix]

No there is no 'auto shut off', it sounds like you are either hitting reserve-the point where you need to switch the tank over to the reserve on both fuel petcocks, or you are actually out of fuel-my XS would be but only get 25-28 MPG depending on how fast I go. YOU DO KNOW ABOUT THE RESEVE SETTING RIGHT?

Anyway here is how to test the fuel gage set up on a standard:


Regulator- this is a black box located inside the tach housing mounted on the back side of the sealed part of tank (most of the time this is what is bad). Use a volt meter (turn the key on) to check the plug in the headlight housing going to tach. Brown wire to ground should by 12 volt supply from battery (if not bad battery or fuse or wiring). Green to ground should be about 7 volts (if not regulator is bad). If good so far, then disconnect fuel tank sender connector and check green wire there, should be about 7 volts..if not broken wire of bad connection between fuel tank and headlight bucket. If that is OK check the sedor unit as follows...........

Sender- this is the float inside the tank. Unplug the fuel sender connector at the rear of the tank, the book says to remove it from tank (but i would slowly add or siphon out fuel with it installed or would empty tank then get a thick copper wire (no sparks) and actuate the float by hand by this will not alert you to a leaky float). Anyway a resistance check on rX1 should give you: Full 6-10 ohms, half 28.5-36.5 ohms, and empty 75-85 ohms. It should change resistance smoothly and evenly thoughout the range of motion.

If all this checks out the actual gauge is the problem and I would look to ebay for a spare tach.

[bbs1980xs1100g]

first thanks for the info, I havent done the tests yet because im suspecting a fuel petcock leak? ill update later

[bbs1980xs1100g]

I cleaned the contacs of the two wires 12inches from sender. got lucky only cost a few wire connectors.

[sixtysix]

Glad you got the problem worked out!

[Bud Manley]

I just checked mine out and the regulator is definitley bad. Is there a part number for it?