Troy-Bilt 78 Manual De Usuario

There are four failure modes for the EVAP system:

•

A leak in the system - will allow dirt ingestion.

•

A blockage in the system (between the canister and the fuel tank) - acts a plugged vent.

•

A blockage in the system (between the canister and the control panel) - The canister can not purge its 
vapors.

•

Charcoal canister poisoned (raw fuel in the canister) - prevents the canister from absorbing fuel vapors.

NOTE: The only failure mode that will affect the operation of the engine in a way the operator will notice is a 

blockage in the system.

To test the system for a blockage:

1.

Remove the fuel cap.

2.

Clamp off the hose that runs from the canister to the 
control panel. See Figure 4.12.

3.

Attach a vacuum pump to the vent port of the char-
coal canister. See Figure 4.12.

4.

Apply a vacuum to the canister.

NOTE: When applying the vacuum, squeeze the 

pump slowly. Too much vacuum can close 
the roll over valve giving a false reading.

5.

If the canister does not hold a vacuum, the canister 
and the roll over valve are working properly.

NOTE: If the canister does hold a vacuum, test the 

roll over valve to determine if the roll over 
valve or the canister is at fault.

Charcoal canister

For Parts Call 606-678-9623 or 606-561-4983

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