Fuel gauge reading empty when full?

[JTT]

So today I'm riding home from work.  Fuel gauge has been working perfectly since I got the bike a few weeks back.   I was getting low on fuel.  Fuel light came on as normal.  I stopped, and filled up, only the gauge only came up to just over 1/4 and shortly after showed empty and fuel light came on again.  Tank was still full (I checked).

Any ideas what would cause the fuel gauge and light to suddenly read wrong?

[Nimrod11]

The old fuel sender problem... sorry, sounds like you'll need a new fuel level sensor. This apparently happens with many Tigers but the word is that the new ones are made of a better material and last longer.

http://tigertriple.com/forum/viewtopic. ... c&start=20 (http://tigertriple.com/forum/index.php/topic,6099&postdays=0&postorder=asc&start=20)

You'll also have to take the tank off and drain all the fuel.

[jphish]

Well my gauge is good for "relative" indication of fuel presence, but aint linear in its volumetric disappearance rate. Stays up at full for 100 mi - then drops like a rock to almost empty. Hovers there for the remainder, til the light shines. I just use the trip meter. No fuel gauge on my Uly either - unless you count the 'doomsday' FTRIP which counts the miles you have (about 30) til your empty. I start lookin for gas at about 200mi - Zumo also tells me if fuel is near by. DO like that 6+ gal tank !!

[daveb]

JTT.
Sound like you have a broken wire somewhere in the system, this could be on the resistance boards in the sender unit, a poor connection somewhere or a bad earth.
causing the gauge and sender to go to zero. Tere are 2 design ways to bring on the low fuel light on is via the ECU when the resistance reachs a level lets say 15 ohms when this will bring the light on. the other method is in the sender unit. on the resistance plate there will be a separate follower, when this reach an earth pad inside the sender then the curcuit is complete an brings on the light.

I am just wandering if the float inside the tank has absorbed fuel making it heavy, resulting in not recording the true amount of fuel.


Jphish
The fuel sender is a resistance type, the the charateristic curve from the sender is non-linear.
for example, the send unit could be 10-180 ohms.
10 ohms for empty and 180ohms at full, the charateristic for 1/2 tank might be 50.
When we design fuel gauges we always show the gauge as linear, this is when you look at the gauge half tank should be mid scale. if they were design to match the senders then half tank might be in 1/4 tank position which cosmetically looks wrong.

Also the shape of tank has to be concidered and how the sender float arm moves inside the tank.

[Bixxer Bob]

So today I'm riding home from work.  Fuel gauge has been working perfectly since I got the bike a few weeks back.   I was getting low on fuel.  Fuel light came on as normal.  I stopped, and filled up, only the gauge only came up to just over 1/4 and shortly after showed empty and fuel light came on again.  Tank was still full (I checked).

Any ideas what would cause the fuel gauge and light to suddenly read wrong?

I'm with Nimrod; mine does it sporadically; like JTT, just after filling up.  It usually sorts itself after a few miles.  Happens often enought to make me nervous when the fuel warning light hasn't come on by 210 miles.  I normally bottle out and fill up.... :roll:

[BigMark]

You put too much in, sent the gauge into a fit...

Mine does that, after about 20 miles or so it sorts itself out..

[JTT]

You put too much in, sent the gauge into a fit...

Mine does that, after about 20 miles or so it sorts itself out..

I thought that first, but I've put 70-80 miles and it's still showing empty and light still on  :(

I'll do some hunting for a loose, or broken wire.  It just seems odd that it was working fine, the stopped immediately after a fill up.

[walker]

mine has done that once or twice.... usually clears itself up once the tank gets low enough.

[Timbox2]

Mine did this back in February not long after Id bought mine.

As I wanted to change the fuel filter anyway I took the Tank off and dropped the fuel sender as well.

The float had twisted on the board locking itself at the bottom. I managed to free it off and put it back.

Its worked fine ever since.

I did think about buying a new sender until the dealer actually said to me, "Its a bad design, and if I sell you a new one it will probably do the same in a year or so", thanks for the honesty I thought.
 :lol:

[Bixxer Bob]

Thanks for the memory jogger Tim(it's me age), I'd forgotten about that.  And if it's not sorted itself in a few miles then likely DaveB or yourself are right.

[JTT]

Weill, I'm beginning to believe it is the fuel sender and I guess I'll have to suck it up and remove it to check.  I ran the tank down to fairly empty and refilled...gauge did come up some, to about the beginning of the "red", then within 25kms it had dropped and the warning light back on.  I'm curious how the warning light works, as I disconnected the fuel sender electrical connector, yet the light remained on??

[daveb]

A simple test you can do, when the sender is out of the tank, reconnect electrical connection and move the float arm from 1 stop to another, you may have to hold id it 1 postion to allow the gauge to catch up with the signal as fuel gauges are damped.

The warning light staying on when the sender is disconnected this could be that the low fuel warning light is generated by a signal not driven from the sender, so when the resistance is set to a low ohms value lets say 15 ohms or less the light comes on, so when sender not connected there is no signal zero ohms so the warning light comes on.

[JTT]

That would make sense Dave, thanks!  I may try to get the tank and sensor off this weekend.

This is a bit of a bonehead question, but bare with me as this is (hard to believe as it is...) my first fuel injected bike.  I'm assuming I have to syphon it out through the filler.

[KuzzinKenny]

Hey JTT !! the tank connectors are self seal units so unless yer tanks full and heavy you`ll have to syphon it !! if its not full, once its off you can lean it over to one side and remove the panel on the tank !! not done it meself yet but it should be ok !!  :shock:

KK

[JTT]

Update...tank off, sender out.  Put a meter on it.  Measures 13.6 ohm full, 92.7 ohm empty.  Sliding up and down the scale seems to work fine, as resistance increases as the float moves to the bottom and decreases as the float moves to the top.  Gotta think this is the way it should work.  No sign of damage to the wires or such.

Guess it's not the sending unit?

Oh and the self sealing connectors?  yeah, well they pissed fuel all over the place