G9 ELectric 36V Hard Acceleration Prob

[ejallison1]

Need help diagnosing what the problem is with this (1991) G9 electric. When initially pressing the accelerator it takes off like a jack rabbit (wide open throttle) instead of a nice smooth controlled acceleration. This problem started suddenly. If press the accelerator from a dead stop it will squeal the tires.

In researching this I am thinking it has something to do with either the mechanical speed controller or the "throttle sensor". Fairly mechanical but am definitely a newbie on these carts so if I am on the wrong path or need to consider another potential problem I'm all ears.


The leading edge of the metal piece on the arm that moves when the accelerator is pressed is slightly burgered but does not have any arcing on the contact areas. The cables that run from the speed controller to the different points on the large resistor coil that sits in the middle of the battery bay seem good. Is it possible that either the big resistor coil itself has fried or that the clamps that are the attachment points have given out.

I don't know where the throttle sensor is located but according to the electrical schematic from Yamaha it is suppose to have one. Could the throttle sensor cause this type of problem? How do you test it?

I am thinking the big solenoid that passes current to the speed controller is not the problem since it is passing current?

I can find the metal contact pads for the speed controller but if the resistor coil itself needs replaced where can I get one or are they unobtanium.

Any suggestions greatly appreciated.

[cgtech]

The arm is moving smoothly? If you have resistor coils, you have no "speed sensor".

[ejallison1]

Thanks-one less potential problem not having a throttle sensor!

The arm seems to move smoothly. I ordered the movable arm and the metal pad that is attached-should arrive in a couple of days. As I said there is a small burgered up area on the leading edge of the metal pad on the moveable arm- can I put that on a wire wheel to clean it up a bit.

I'm guessing that if the above doesn't cure it then the coil itself or the resistor studs may be bad? Am going to recheck the cables again. Also put it back up in the air and have a helper help with the accelerator petal and get some readings with the multimeter at each resistor stud.

Any suggestions on what to check greatly appreciated!

[cgtech]

Dont allow the motor to spin at full speed with the wheels up in the air (no load). The motor can be destroyed by over revving.