Should I use Sea Foam before starting a jet ski that has been sitting? [SOLVED]

Great question, Jeff.

Whenever a tank of gas sits for a long time (longer than 6 months), the gas can degrade and form varnish and residues. These residues can plug up a fuel system and cause the engine to run very poorly (and sometimes not want to start at all).

Sea Foam cleans the residues and varnish so the engine can run well. It would definitely be a good time to use Sea Foam. Marine PRO (made specifically for marine engines) would be the best Sea Foam product to use.

Here’s what I’d do: first, start by draining the fuel tank. Three-year-old gas will be pretty degraded, so you’ll want to get it out of there. Then, add a gallon of fresh non-oxygenated gas along with a can of Marine PRO. Start the engine and let it run for 10-15 minutes. Then, let turn it off and let it soak overnight. Start the engine back up, and take it for a good hard run on the lake.

If you don’t have time to let it sit overnight, just go for a ride after adding the fresh gas and Marine PRO.

The high concentration of Marine PRO in the fuel will do a good job cleaning up any varnish or residues that have formed in the fuel system.

After that, fill up the tank with fresh fuel and add 1 oz of Marine PRO per gallon for preventative maintenance.

Hope that helps and let us know what happens!