10
Engine
Safety Gauges
The engine is equipped with instrument panels which contain shutdown gauges for High
Engine Coolant Temperature and Low Engine Oil Pressure. The fault light for the Air
Fuel Ratio controller indicates malfunction of the controller. Causes could be the O2
sensor needs replacement but commonly the unit just needs the power to be cycled. This
is easily accomplished by tripping and resetting the breakers in the back of the panel.
Fuel System
The engine fuel system is simple to adjust using the supplied gauges and LCD readout.
The Fisher S402 regulator is used to regulate the fuel pressure. Set at 17” H2O as
indicated by the Fuel Press gauge on the instrument panel.
Powervalve limits the maximum horsepower output of the engine by restricting the gas
flow. The initial setting is 7 mm (9/32 in), measured from the top of the adjusting screw
to the top of the nut.
Fuel ratio is adjusted by removing the top cap of the Maxitrol and turning the adjuster.
An initial setpoint is 10 mm (3/8 in) measured from the top of the Maxitrol to the top of
the adjuster. Turning the adjuster downwards richens and upwards leans the mixture.
Adjustment
If the mixture is badly out of adjustment set the power valve and mixture to the stock
settings above. Otherwise begin at the next step.
1. Remove one of the wires to the solenoid so there is no adjustment by the air/fuel
ratio controller. Ensure it does not touch any metallic parts or it may blow a fuse.
2. Bring the engine to idle.
3. Adjust the mixture until the light on the AFR Controller blinks from red to green.
If it is solid red then lean it, and if solid green richen it. Move in small
adjustments, 1/8 turn, and after each adjustment seal the top of the Maxitrol to get
an accurate reading. Repeat until the color of the LCD has just changed. Replace
the Maxitrol top cap.
4. Plug in the wire previously removed.
5. The duty cycle LCDs should indicate a duty cycle and the single LCD should be
blinking from green to red.
6. Bring the compressor up to power.
7. The duty cycle should be around 50% and the green-red LCD blinking back and
forth.
8. If the engine leans out (goes solid green) or the duty cycle goes to 0% the power
valve is set too far in. To allow more gas turn out the power valve in small
increments until the duty cycle rises and the blinking returns. Lock it in place.
9. A few iterations may be required to get it right. On the second try start back at the
idle setting with the solenoid wires both connected.
10. You now have the mixture set to stoichiometric across the rpm/power band. The
goal of this procedure is to have a green-red blinking LCD with about a 50% duty
cycle when the compressor is at operating conditions.
