Watch out for your Throttle Position Sensor (TPS) when jetting

[Woody_393]

THROTTLE POSITION SENSOR

The throttle position on bluedog's quad broke off.... the three wires just broke off, they look like standard, thin copper-stranded wire, a black one, a blue one and a black and blue one. The wire pulled out from the little switch. I guess with bending back and forth they break just like any wire. They go into a hard switch that is attached by a screw to the side of the carb that rotates with the change of throttle to send a signal to the carburetor.

The wires are actually pretty delicate when hooked up to that heavy carb, and knowing this now it might be better to either elongate or lengthen the wires to make jetting easier or to unplug the switch TPS before rejetting. PULLING on them can either:

1.. move the TPS and throw it out of whack. or
2. Break the wires off. (you don't even have to pull that hard, the carb can just slightly slip while in the twisted position).

We thought we would just walk on down and buy another one for 19 bucks.

Well, at Radio shack that is what they cost, but for the Yamaha, the part is 150 dollars. I think Labor in Japan is a bit higher than here, or it must cost a few bucks to ship it from Japan, being that it weighs almost one whole ounce!

The sensor hooks on to the side of the carb and senses the position of the throttle, and sends back to the computer a voltage from 0.7 volts to 5.0 volts. This is done by a little rotating switch called a variable resister, of which you can buy a pack of twenty at Radio shack for 4.99. But the Special Yamaha resistor costs 150 dollars, cause it is encased and made tougher by some plastic that is worth 17 times the price of gold by weight.

So BE CAREFUL and don't yank on the TPS! This is not the TORS unit, the carburetor needs to have this information for timing advancement or you will lose power. And we don't want to lose power!

So you broke it, what do you do? Remove it and see if you can salvage it and solder it, but the wires break off at the edge and it is HARD to get enough to solder. We will be putting JB weld on the point where the wires enter the carb on White dogs quad, so they can keep bending right at that edge. we are also going to lengthen the wires by 4 inches to make it easier to jet.

Anyway, watch out! You know, you should take a felt marker and MARK the POSITION of your TPS where it sits RIGHT NOW, cause if you ever accidentally move it, then the voltage goes incorrect and the quad won't idle right nor run right. Even pulling on it slightly can throw it out of whack.

To reset it you have to get a voltmeter that reads up to 20 volts and put the negative on the black wire and the positive on the blue wire, then turn on the key to the quad, loosen the screw and move the TPS around till the VOLTAGE reads 0.7 volts or real close to it, then re-tighten the screw. VERY EASY but could cost you 50 bucks to have that done.

How do you hook up the meter? At the plastic clip you can , with two peoples help, get the probe to touch through the plastic connector. Another way is to use two very thin sewing needles, put one into each wire, and use an alligator clip to measure the voltage. very easy.

We may have to shoot a vido on it!

Anyway thanks! and this has been an update on what to watch out for for the TPS.

If you rejetted and it doesn't run right, this is probably what they will check to make sure it isnt something easy.

I'll bet with time everyones goes out and needs readjusting..

Might as well adjust it tonight!

THANKS AGAIN

HERE IS HOW IT WORKS (those who understand schematics. (About 1 dollar worth of parts) that is 15000 percent profit.

[Woody_393]