Genie S-60 dies when revved up

[metalman]

I have a 1998 S-60 dual fuel with an LRG 423engine, serial #2784. The problem that I'm having is the machine will run fine on turtle mode, but when I switch to rabbit mode or depress the pedal in the basket, the engine will spit and sputter and stall. It always starts right back up again. I have ran a bottle of sea foam through the gas tank, thinking that it may be an ethanol issue. I have also changed the coolant temp sensor. Any ideas or suggestions would be greatly appreciated. Thanks

 

[willie59]

Zenith carburetor?

 

[metalman]

Not sure, I will have to look

 

[willie59]

If it does, can't say for sure it's your problem, but most Zenith carbs have a vacuum operated throttle primer. It's a small square plate on the side of the carb body that's held in place by 4 small machine screws. Diaphram could be bad, one of the check balls is malfunctioning, or the drilled passages that feed or leave the chamber could be clogged.

 

[metalman]

Thanks, I will check it out tomorrow and let you know.

 

[metalman]

Hi Willie, Yes it is a zenith carburetor. I took carb apart and cleaned it, held diaphragm up to the light and didn't see anything, I didn't see any check balls that you spoke of. I also replaced the fuel shut-off solenoid, because the wire on the old one had some corrosion from where it looked like someone had used a circuit tester. The machine runs a lot better, but now the engine starts loping and acts like it wants to stall when you try to drive it or use more than one boom function at a time. When it starts doing this if you let off the joystick, it straightens right out and runs fine until you put it under load again. Any ideas?

 

[willie59]

Yes, you need to adjust the Gain in the Precision Governor control box. It's a black box mounted somewhere in the engine compartment, roughly 8" long x 5" wide. Remove the control box from its mounting and flip if over to the backside. You'll find 4 phillips head screw holding a metal cover on the back of the control box, remove the cover. Inside you'll see a printed circuit board. There's typically 3 trim pots on that circuit board, High RPM, Idle (or Lo), and Gain, sometimes there's a 4th trim pot AUX. The High and Idle trim pots are typically near the edge of the circuit board, the gain is typically near the center, you should be able to read GAIN printed in small letters on the circuit board. Turn the Gain trim pot adjuster CCW just slightly, it doesn't take much, really a tiny bit of a turn of the screw to make a big difference, turn it CCW just enough to make the engine stop loping.