Fuel gauge and warning light

chocker · June 22, 2012, 06:04:54 PM

Hi,
I seem to have a problem with my fuel gauge. When I fill it, it shows as full which is great. It seems to go down quite quickly. I mean to say that after about 200km (120miles) it is down to empty and my low fuel light comes on not long after that. I open my tank and there seems to be a good amount of fuel left but when I tried to continue once when this happened the motor was giving out and I had to switch to the reserve. It then ran fine. I didn't want to take the chance on running it too long on reserve so I filled it up again. Can anyone tell me what might possibly be the problem.

Thanks,
Mark

FJmonkey · June 22, 2012, 09:05:29 PM

Quote from: chocker on June 22, 2012, 06:04:54 PM
Hi,
I seem to have a problem with my fuel gauge. When I fill it, it shows as full which is great. It seems to go down quite quickly. I mean to say that after about 200km (120miles) it is down to empty and my low fuel light comes on not long after that. I open my tank and there seems to be a good amount of fuel left but when I tried to continue once when this happened the motor was giving out and I had to switch to the reserve. It then ran fine. I didn't want to take the chance on running it too long on reserve so I filled it up again. Can anyone tell me what might possibly be the problem.

Thanks,
Mark

That's an old warranty issue. Take it back to the dealer and they will fix it..

.

RichBaker · June 23, 2012, 02:28:45 AM

How much does it take to fill?

chocker · June 23, 2012, 07:54:54 PM

I guess it takes between 12 - 15 litres when I fill up. The fuel capacity is 24 litres. I just don't understand it. Was there a warranty issue with this at some point?

Mark

FJmonkey · June 23, 2012, 08:05:43 PM

Quote from: chocker on June 23, 2012, 07:54:54 PM
I guess it takes between 12 - 15 litres when I fill up. The fuel capacity is 24 litres. I just don't understand it. Was there a warranty issue with this at some point?

Mark

I am just stirring the pot, your problem is new to me. I wonder if something got bent inside the tank and is sending the wrong information. If there is a float involved it could be compromised and not floating very well, hence giving signals of lower fuel levels. Even a bad float can be pushed up when the system is full. But when the level drops it will quickly indicate much lower levels. I have a spare 86/87 tank that is empty, maybe I will get a light and inspection mirror to see how the sender works in the tank. I could borrow the inspection camera from work, it has 40 inches of flexible extension with a lens and light at the end....

chocker · June 23, 2012, 08:10:26 PM

I guess it's not so easy to see the float and if it is the problem is it hard to replace or actually be able to repair it.

Mark

Pat Conlon · June 24, 2012, 03:02:13 PM

Mark is right. The float may be the issue. Take the float out and see if has any fluid in it. Put the float in a bowl of water and see If any air bubbles escape the float. Leave the float underwater overnight.
If all is well...
You may just need to adjust the float rod.
Fill your tank with 12 liters and adjust the rod so that your gauge reads 1/2 full.
It may take several tries to get the rod bent where it needs to be...

Don't bother adjusting the rod if your float is not 100 percent. HTH. Pat

chocker · June 24, 2012, 07:00:47 PM

I just filled my tank so I will wait until it is showing empty then drain and refill to half (approximately 12 litres). Is it easy to adjust the float without removing the tank.

Mark

Pat Conlon · June 24, 2012, 09:52:05 PM

No, it is not easy to access the float thru the filler hole. All the FJ tanks I've seen have a sleeve at the filler cap which prevents access to the float from the top.
I had to remove the tank, drain it, flip it over, peel back the heat shielding, remove the float assembly and bend the rod. Reassemble in reverse order and refill the tank.
My first try I bent the float rod the wrong way.....made it worse...visualize and remember the orientation of the float as it sits within the tank, a key point.
It took me two more tries to get the float just right. Remember to check the float-fuel gauge reading with the tank on the rubbers and the bike on the ground, not on the center stand.

Yea, it was a hassle... I don't want to do it again.

chocker · June 27, 2012, 07:20:34 PM

I was looking at the fuel sender unit in the tank with a flashlight and the float seems to be at the right level where the gas is but it is showing about 1/8 full when it is much more than that. I can do about 140 kms for half a tank then the other half goes down in about 60 kms approximately. I think it might not be a bend in the sending unit but the unit itself is defective. I cleaned the connections for the unit and used dielectric grease. How would I go about testing the unit.

Mark

Harvy · June 27, 2012, 07:57:00 PM

Quote from: chocker on June 27, 2012, 07:20:34 PM
I was looking at the fuel sender unit in the tank with a flashlight and the float seems to be at the right level where the gas is but it is showing about 1/8 full when it is much more than that. I can do about 140 kms for half a tank then the other half goes down in about 60 kms approximately. I think it might not be a bend in the sending unit but the unit itself is defective. I cleaned the connections for the unit and used dielectric grease. How would I go about testing the unit.

Mark

Mark, that more or less makes sense. The top half of the tank does not have the "backbone" hump. So you would expect to get more out of the top half.
I would think however, that your FJ is using more fuel than it should if you are only getting 200Kms to a tank full.
I can regularly achieve 300Kms around town and 350Kms on a trip.

Harvy

RichBaker · June 27, 2012, 10:08:24 PM

Quote from: chocker on June 27, 2012, 07:20:34 PM
I was looking at the fuel sender unit in the tank with a flashlight and the float seems to be at the right level where the gas is but it is showing about 1/8 full when it is much more than that. I can do about 140 kms for half a tank then the other half goes down in about 60 kms approximately. I think it might not be a bend in the sending unit but the unit itself is defective. I cleaned the connections for the unit and used dielectric grease. How would I go about testing the unit.

Mark

The sender is a variable resistor, you'd need an ohmmeter and need to be able to swing the float thru it's full range of travel.... You be looking for any sort of large non-linearity. If it was open, you'd see either a "FULL" or "EMPTY" indication on the gauge itself, no matter how much fuel was in there ( probably "E", but I'm not sure).

Pat Conlon · June 27, 2012, 10:51:01 PM

What I think* happened to my bike causing my gas gauge to become inaccurate, was when I raised my back suspension.
I noticed that the float is positioned towards that back area of my tank.

With the rear raised, the fuel level within the tank is now lower at the back of the tank... and higher at the front.
That's why my gas gauge read lower than the actual amount left in the tank.

Filling my tank 1/2 full, and bending the float rod to get that 1/2 tank reading, solved the problem.

*Just a theory

chocker · June 28, 2012, 09:18:09 AM

I have an ohmmeter which is in my vole meter but where exactly do I connect it. Do I just disconnect the line running from the sending unit and attact it there. Would you happen to have a picture.

Thanks,
Mark

Sabre093 · June 28, 2012, 03:26:40 PM

I read somewhere that res will be needed at approx 5 litres left in tank...I've had bone dry empty on gauge,and no light or res and put 21-22 ltrs in it to fill.Is there a fuse or something that i may have blown,and that is why fuel light and res has not been used yet since i owned bike?

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Fuel gauge and warning light