How to switch dual fuel portable generator between gasoline and liquid propane?

Dual fuel portable generators can easily be switched between a gasoline or liquid propane fuel source. This article describes the process in detail.

Environment

This procedure applies to dual fuel portable generators that are designed to run on either gasoline or liquid propane. To determine the correct fuel source for your generator, consult the owner's manual: Where can I download a user manual for my Generac portable generator?

Note: This article does not cover the complete start-up procedure for dual fuel generators. Before starting the generator, make sure oil levels are correct. To ensure you are starting the generator properly, reference the owner's manual.

Before starting

• Use only standard 20- or 30-pound capacity LP cylinders with Type 1, right hand Acme threads with duel fuel generator.
• Verify qualification date on cylinder has not expired.
• Do not use rusted or damaged cylinders.
• All new cylinders must be purged of air and moisture prior to filling.
• Used cylinders that have not been plugged or kept closed must also be purged.
• The purging process should be done by the propane gas supplier. (Cylinders from an exchange supplier should have been purged and properly filled by supplier). 

To switch from gasoline to liquid propane:

Note: LP vapor 1st stage regulator inlet pressure is approximately 30 psi at 0 °F, and 218 psi at 100 °F.

1. Remove safety plugs or caps from cylinder valve, generator mounted regulator, and regulator connecting hose ends.

2. See Figure 2-14. With LP tank valve closed, attach LP regulator connecting hose into valve. Turn plastic coupling from the hose right (clockwise) to tighten hose assembly onto LP tank.

3. See Figure 2-15. Connect opposite regulator connecting hose end to generator at mounted LP primary regulator with the 19mm wrench. 

4. See Figure 2-16. Turn LP tank valve ON and check for leaks by spraying soapy water to check connections. If bubbles appear, become larger in size, or increase in number, a leak exists. If a leak exists, this must be corrected before using generator. Contact your local IASD for assistance.

5. Before starting the generator, Turn engine GAS/LP dial to LIQUID PROPANE. 

To switch from liquid propane to gasoline:

1. If a propane tank is connected to the generator, verify its valve is turned OFF.

2. Disconnect the hose from the generator and the propane tank cylinder.

3. Turn the engine GAS/LP dial to GAS. 

4. Fill the gas tank with clean, fresh, unleaded gasoline. It's important to use fuel with a minimum rating of 87 octane.

Additional reminders 

• Always position cylinder so the connection between the valve and regulator won’t cause sharp bends or kinks in hose. 
• When transporting and storing, keep cylinder secured in an upright position with cylinder valve turned off and the outlet plugged.
• Keep cylinders away from heat and ventilated when in a vehicle.