The fuel gauge does not work on jonway yy250t alias Roketa By miky6719 (Read 4,269 times)

[miky6719]

I have a scooter Jonway Roketa yy250t similar to, the fuel gauge does not work, the pointer remains at the bottom as if the tank was empty, how can I tell if the problem is the indicator or float?

How can I test the wires?


imageshack.com/a/img833/2005/4ero.jpg

imageshack.com/a/img196/8452/ulai.jpg


Thanks

[Alleyoop]

The easy way is get wire and put a bend in it and stick it in the tank turn the key on and hook the float wire and pull up and see if the gauge registers. IF it does then either the plastic float is in pieces or the arm mechanism is loose and not making contact with the resister plate or the swivel part is to tight and you will have to take it out and fix it or get a new sensor.

It is rarely the gauge it usually is the float mechanism itself that has a problem or the whole arm is loose or tight or the float disintegrated.
Also check to see that the sensor is plugged in.
Alleyoop

Here I wrote up a whole thing on it cause it happened to me as well

scooterdoc.proboards.com/thread/8701

[Bashan]

Do what the big fella says.....believe me.....you better do it. If you wanted to test the wires you could check continuity from where the wires connect to the gauge back to the dash pigtail. And then do the same with the wires running back through the harness to the sensor. Just follow the color, they're usually blue/white and yellow/white. There is always a power source too, usually black or brown/black. You could multi that by putting one probe on it at the gauge, the other on a ground spot, and turn on the key. You should get 12v DC.

[Alleyoop]

Yep you better do it or ELSE:

[miky6719]

If I wanted to remove the fuel level sensor, how should I do? Gasoline take it off by pulling the rubber tube to the bottom of the tank right? And then to remove the probe just unscrew the four bolts?

thanks

Hello

[Alleyoop]

You got it TOYOTA,
Alleyoop

[miky6719]

In the meantime, I emptied the tank, I put a piece of wire with a hook and tried to lift the float, has little hike and also the needle moves a little.

Thanks 

Bye

[Alleyoop]

Great so your gauge is fine the float system has a problem.
So take it out and see if the float is still on or disintegrated or the swivel arm is loose or to tight. You can test it once out just move it with your hand up and down and see if the gauge registers.
If the push on lock washer is to tight and making it bind loosen the washer on the wire NOT TO MUCH just enough so it does not bind. If it is to loose then the swivel part with the contacts is not touching the resistor plate and you have to tighten the push on lock washer.
Alleyoop

This Position should register FULL:



This Position should register EMPTY:



This is what is makes it register:

[miky6719]

Hello, I disassembled the level sensor and I took some pictures and I measured the voltage here they are:



In position empty:

imageshack.com/a/img713/7088/aytm.jpg

imageshack.com/a/img845/7188/tnh9.jpg



in position full

imageshack.com/a/img89/5387/os5j.jpg

imageshack.com/a/img59/1663/ygyf.jpg

imageshack.com/a/img24/4098/kdg3.jpg

imageshack.com/a/img28/6431/a1r6.jpg

imageshack.com/a/img191/7411/c34z.jpg

imageshack.com/a/img22/8143/uizt.jpg

Can you see the problem?

[Alleyoop]

Sorry I cannot help with the readings, I am not an electrical guru, I am a motor head, motors, carbs,cvts and trannys. But there are some on here that now some electrics and I am sure they will chime in and possibly help.

So with the sensor out like that if you have it plugged in and move the arm up and down it does not register is that correct? Did you check if the brushs in back of the swivel part are intact?
Alleyoop

[DrRocco]

Are the different voltage readings on full from different trials? That is say did you move it empty to full and check, then empty to full and check....or did you keep it on full and the voltage steadily increased?

[miky6719]

Hello, in the wafer level sensor there are three electrical contacts that correspond to the wires, the middle think it is in fact the mass is at 0 volts the other two are at 12 volts when it is empty. When I move the float position in full, the tensions in the left contact becomes 4.9 volts, and the contact to the right becomes 2.46 volts, in the picture you can see where touch with the tip of the meter.



thanks

[DrRocco]

It's hard to really see what's going on without actually being there I'm pretty sure that the float mechanism is attached to a potentiometer. 12V and Ground get connected to A and B. W would be the output to your fuel gauge, and the voltage would vary as the float moves up and down in the tank. You can try hitting it with some electrical contact cleaner and see if that improves things. Otherwise, you may need a new sensor.

[miky6719]

I did another test, I unscrewed the screws behind the meter and I measured the resistance with the multimeter between the wire white/ blue and the wire white/yellow. By placing the probe in place full I measure 600 ohms then continuing to move it to the empty position midway becomes about 400 ohms when in position empty again I measure 600 ohms, it is strange?

An answers, the black wire is the power of the instrument (12V)?

ThANKS

[DrRocco]

I'm flying blind here. Maybe Alley or someone else could help out. My guess is that the three wires on the back of your gauge are Ground, 12VDC for backlighting, and the voltage coming off the wiper on the fuel sensor potentiometer. Based on the pictures you posted, you're measuring between the two positive inputs to the gauge. Solid green wire is ground on my scoot. I assume it's the same on yours. You might try keeping one multimeter probe on the green wire, then choose one of the others. Operate the fuel sensor and see if it changes. Then move your lead to the other wire and repeat. I'm guessing one will remain steady at 12VDC and the other will vary based upon the position of the lever on your fuel sensor mechanism.