3 wheel EZgo troubleshooting

[TheOldMan]

I purchased a 3 wheeler from an estate sale, and replaced all 6 batteries. It has a "flat place" in the throttle. If you ease down on the pedal, it will go past and spin the wheels as it takes off. If you hit a bump or push the pedal too far, as to climb a small hill, or try to start and stop quite a few times, it will not go forward until it kinda cools off a bit. Seems to always move in reverse.
Where do I start to look for the problem?

[JohnnieB]

The first thing would be to figure out what type drive system, controller or Resistor.

[TheOldMan]

How do I tell, and what is usual for a 3 wheeler?

[JohnnieB]

Originally Posted by TheOldMan

How do I tell, and what is usual for a 3 wheeler?

Does it have resistor coils in a box between the batteries, or mounted behind the battery box

[yurtle]

If it's a resistor cart, you may have a bad/dirty connection on the throttle switch. You can download the Owners, Service, and Parts manuals from the Stickies.

[scottyb]

Likely it's resistor coil drive. My guess is you have 2 problems working hand in hand. One the speed wiper has a burnt contact or resistor coil is broke and the other problem could be a bad contact in the F&R

Both of these devices need to be dismantled and refreshed or replaced during regular maintenance.

[TheOldMan]

Finally got a chance to look at this thing. There are no resistor coils. The s/n is
957644 if that helps any. Looking at the stickies, I'd say it's a series, There's a large plastic cover held on with a wing nut that when I remove it, I find a micro switch That is activated by the throttle pedal, and is mounted next to a
large cube w/several wires on top. and cooling fins on the back. When depressing the accelerator, the microswitch picks the solenoid (click), then there is considerable movement before the motor is engaged. What I would call a "flat spot" in the speed control. This flat spot is present in both forward and reverse, however the loss of driving power seems to be only in forward.
I've looked at the schematics in the stickies, but really don't know which one I have.

[kernal]

957644 indicates a 1996 Medalist gas. Are you sure you got the numbers right?

[TheOldMan]

Update! S/N 957644 and the metal body tells me this is a 1995. If so, it has to be a series rather than a dcs or PDS. When I bought and installed new batteries, I replaced all of the connectors I could find that had any hint of corrosion. I've been through the troubleshooting guide as listed in the stickies, and I find no problem.
What I do see, is that where the throttle rod comes back from the firewall, when it actuates the micro switch, it has a kind of bell crank arrangement that turns a spring returned shaft going into a control box. I'm assuming that is a potentiometer of some sort. The end of that shaft has a screw driver slot, and the bell crank is a pinch connection. I'm assuming that is an arrangement to allow the throttle rod to start potentiometer movement immediately on activating the micro switch. I don't want to start adjusting things, or removing parts until I have more information.
How about a theory of operation of how all these parts work together, or a schematic rather than a wiring diagram. Then I could maybe see what it's supposed to do.

[JohnnieB]

Sounds like you have a Pot-Box type throttle. (0-5k potentiometer)

The attached schematic may not be exactly like you cart, but it ought to be close and it does show how the Pot-Box works.

To check the throttle, remove the small black and small white wires from the controller and measure between the wires with an Ohmmeter.

F/R selector in Forward or Neutral
Pedal up should read about Zero Ohms.
Slowly press pedal to floor.
The Ohmic value should increase smoothly to about 5,000 Ohms.
If there is any jumps over 7,000 Ohms, the controller will sense that as a bad throttle signal and shut down.

F/R selector in Reverse, you should get 0 to 2,500 Ohms.
(A microswitch on the F/R switch assembly places a fix 5k resistor in parallel with the 0-5k pot)

If possible. post pictures of cart.