Fuel gauge not working

Slydynbye

Will ride for Pie
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Sep 3, 2007
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Fremont, California
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2000 ABSII
STOC #
7331
Trying to bring a 94 ABS back to full operation. It has a Ron Majors aux tank on it and the fuel gauge reads empty all the time. the low fuel light works but not the gauge. Which wires on the tank should I be looking at and what should I measure?
 

ST4Sal

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Williamsville, NY
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4812
Slydn, when I first installed my tail dragger the "float" was getting caught on the bulkhead connector holding the hose to the aux fuel.. After taking out the fuel pump assembly ( I think it's what it's called) and reinserting it it all worked properly. hopefully this will fix it for you..
 

John OoSTerhuis

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1991 SSMST1100
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1058
Check the little red 2P connector halfway down the left side of the OEM fuel tank. Wouldn't be the first time that one had been forgotten during a tank removal and gotten damaged. Or it might be as simple as not being (re)connected.

John
via iPhone 6
 
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Slydynbye

Slydynbye

Will ride for Pie
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2000 ABSII
STOC #
7331
Thanks Guys

John, that will be the first thing I check
Sal Good info in case I need to go there.
irish, temp is OK but If I have to pull things apart I will be checking for corrosion as well.

Here's hoping it's a loose connector, wouldn't that be nice?
 
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Slydynbye

Slydynbye

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Uh oh! Well I checked the little connector and it looked good,
I pulled the battery out looking for the connection on the tank, then found I didn't need to once I found where it was.
Reconnected the battery, turned on the ignition, lights came on pressed the starter and everything quit. Even the Clock is out.
Turned off the ignition, clock came back on. Tested the Battery it shows 12.45V w/ignition off .45 when ignition is on.
I checked all the fuses in the pictures.
Just 5 minutes before this I had started and rode the bike. HELP!!!!

Fuse block 1.jpgFuse block 2.jpgAlt harness.jpgAlt harness 2.jpg
 
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Slydynbye

Slydynbye

Will ride for Pie
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Location
Fremont, California
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2000 ABSII
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7331
Well after replacing the Battery things are back to normal except I still have the bad fuel gauge.
Checked the little connector, it was connected.
Checked the resistance from both directions 48 ohms to the Gauge, open to the sensor.
Engine running I get 6.4v from the gauge side.
Took a look inside the tank it looks clean in there, I saw the float arm and reached in with a hooked wire to pull it up.
When it is all the way down I get an open or infinite resistance, with it pulled all the way up I got 8.4 ohm. OK good.

Went and filled up. Sitting still the fuel gauge now shows full, upon acceleration it drops to empty, let off the gas it returns to full. This is with a full tank.
Point the bike uphill empty, downhill full....... ???????
 
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2018 NC750X
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Sounds like you have an open winding on the sending unit. Shouldn't read infinity... doesn't explain the extreme readings with slight angle changes, unless that winding is intermittent.
Does the fuel light stay on all the time? It should only come on for a few seconds, then go off when the tank has sufficient fuel. Just a few thoughts... hope it helps.
 
Joined
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soCal
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'97 ST1100
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687
Sounds like you have an open winding on the sending unit. Shouldn't read infinity...
Thanks for reminding me to look that up, infinity sounded wrong to me too. Factory spec is 10 ohm full, 90 ohm empty. I'm gonna make a guess that when the float drops just a little, the resistance is going way up quickly, and the gauge reading drops to empty because it hits 90 ohms just a little off of full.
 
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Slydynbye

Slydynbye

Will ride for Pie
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Location
Fremont, California
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2000 ABSII
STOC #
7331
The Fuel light is not on. I think it worked when Fuel was low but.....
Going to order a new sender. Thanks All
 
Joined
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687
Going to order a new sender.
looks like they're about $50-60, not too expensive, but....

Before you replace it you could take a look at the old one and see if its just corroded and not making good contact. Haven't looked at the actual unit, but it may be something like a wound wire with a wiper that acts as a center tap for resistance. If some of the wound wire coils are rusted and causing the resistance to shoot up, you may be able to dissolve the rust and get the old one working again. Nothing to lose, you have to take the old one out anyway, so you could try to clean it and measure your success with an ohm meter so you'll know for sure before re-installing it.
 
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Slydynbye

Slydynbye

Will ride for Pie
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Location
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2000 ABSII
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7331
I ordered the Sender and a new Gasket , Bike only has 94K on it and it's not Too expensive, better to get one while I still can and then be sure it works.
Beside that there is a leak when I fill the tank to the Max that I need to check out.
I'm going to pull the Tank when the sender arrives and make double sure there are any fuel Gremlins.
Probably replace all the 22 year old rubber fuel lines too.
I'll let you know what I find out about the sender.
 
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Slydynbye

Slydynbye

Will ride for Pie
Joined
Sep 3, 2007
Messages
1,598
Location
Fremont, California
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2000 ABSII
STOC #
7331
The Sender is in and working. Had to remove the tank which has a Tail dragger aux tank attached.
Dealing with the Fuel line that goes down through the swing arm to that aux tank was a bit fiddly.
Also if I was to pull and re-install the Tank on another ST1100 I would pull the Air cleaner housing off before pulling the Tank, I got it off alright with some struggle but couldn't get it back in without removing the air cleaner housing.

The fuel leak seems to be in the small braided hose that equalizes between the tops of both tanks. The gas just seeps out through the hose.

I'm looking at Braided fuel lines and see a couple of types PTFE and rubber. Whats the best for our Modern fuels?
 
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