No electrician here so need help

[alke46]

I am trying to figure out what is wrong with my fuel gauge. When I fill the tank the gauge shows full but within 15-20 minutes later, it shows empty.
How do I test the electrics on the sending unit?
I have the tank off the bike and the float and sending unit removed. I have cleaned all the connections so what do I do next?
I have a multimeter but do not know the procedure to test the unit that resides inside the tank.
Also I have tested the float to make sure it is free of holes and does float properly. My 1st instinct was that the float was taking on gas and dropping to the
bottom of the tank but no holes were found and it does float like it should.
Any help will be appreciated.

Thanks,

Larry

[Buffalo Bill]

Just to learn a bit about it, measure the resistance between the leads with the float at the top, and at the bottom.
I think the actual problem is in the wiring harness or the fuel gauge. A voltage leak in the wires someplace.

[Steve]

The windings in the level sensor itself are the likely problem. Although they may look OK, there might be a bit of crud on the wiper, so there is not a consistent change in resistance. It has been a while since I have cleaned one up, but I think you can carefully clean the wiper, then bend it a bit so it has more tension on the windings. You can watch the progression of the windings if you set your meter to OHMS (the lower the scale, the better) and clip the meter leads to the leads on the fuel tank.

[alke46]

[QUOTE=Buffalo Bill;2290887]Just to learn a bit about it, measure the resistance between the leads with the float at the top, and at the bottom.

I did this yesterday but was not getting a significant difference from top to bottom.

The windings in the level sensor itself are the likely problem. Although they may look OK, there might be a bit of crud on the wiper, so there is not a consistent change in resistance. It has been a while since I have cleaned one up, but I think you can carefully clean the wiper, then bend it a bit so it has more tension on the windings. You can watch the progression of the windings if you set your meter to OHMS (the lower the scale, the better) and clip the meter leads to the leads on the fuel tank.

Thanks Steve and welcome back to the daily reading and offering your wisdom and insight. Maybe by cleaning the wiper and putting a little more tension on the windings, I can get better results with my meter from top to bottom. I will post my findings after doing this. Fingers crossed that it can be solved so easily.

[alke46]

The windings in the level sensor itself are the likely problem. Although they may look OK, there might be a bit of crud on the wiper, so there is not a consistent change in resistance. It has been a while since I have cleaned one up, but I think you can carefully clean the wiper, then bend it a bit so it has more tension on the windings. You can watch the progression of the windings if you set your meter to OHMS (the lower the scale, the better) and clip the meter leads to the leads on the fuel tank.

I think you hit the nail square on the head Steve.
Using the ohm settings I was getting the following readings: in the empty tank position I was reading from 119.0 - 128.0 At the full tank position it was reading from 16.7 - 19.0

After some good cleaning and making the unit look like new again, I was able to get the following readings: 5.8 @ full and 114.0 empty
The FSM shows the reading should be 3.0 full and 110.0 empty.

I am now happy and think my readings are close enough. Now to put the tank back on the bike and check with empty tank vs. full. Hopefully it will all work out like it should.

Thanks again Steve.

Larry