Diagnostics>Diagnostics using the Clear Cover

Fuel level is not to the top of the fuel filter.

Normal - Do not change the filter.

Fuel level is at the top of the filter. Low power.

Change the filter at the first available opportunity.

Fuel level is at the top of the filter and looks to be full of wax.

Change the filter - Run engine for a minimum of 25 minutes at idle. Do not run at full RPM.

Bubbles are seen flowing in with the fuel.

Check all fittings and lines from the fuel tank to the Fuel Processor. Check lower and upper collar o-rings.

There is a power complaint and the fuel level is below the collar.

Check for a missing grommet at the lower end of the filter or missing/broken spring at top of filter.

Water is noticed in the cover.

Drain the Fuel Processor. Do not drain with the engine running. Drain a full cup at a time. Restart the engine -- shut off engine and continue to drain and restart until ALL water is removed. If engine coolant is visible, follow proper engine pressure testing procedures to determine root cause.

Fuel drains back to the fuel tank when changing the fuel filter or draining separator.

Remove the check valve assembly. Clean or replace and retest.

No engine coolant (Fuel Pro only).

Check for closed cutoff valves at the coolant lines to the Fuel Processor. Make sure the cab heater valve is open.