Good question, Wayne. If the sputtering is caused by fuel gum/varnish, Sea Foam will help clean it up and help overcome the sputtering.

Here’s what I’d do: Wait until you have a low tank of fuel (1-2 gallons). Then, add a full can of Marine PRO to the fuel. Run your boat at least 20 minutes if you can (just don’t run out of gas!), and don’t be afraid to run it hard. After that, refill your fuel tank as normal.

Here’s a (rather lengthy) explanation of why a high concentration works best. For upper engine cleaning (fuel injectors/carburetor circuits & chamber deposits that can affect running performance), it works much better to add the full can to a low amount of fuel for two reasons, 1) the cleaning concentration is considerably greater and, 2) the cleaning effect will start much faster with greater effectiveness. If you were to add Marine PRO to a high volume of tank fuel, it might take several hours of engine running for a lower concentration of the treatment to work its way through the fuel lines and through the engine. Understanding the concentration approach will go a long way in terms of understanding how Sea Foam’s engine products work for overcoming fuel residue restrictions or a rough-running engine. Pay attention to starting, smooth idle, throttle response, hole shot, acceleration, and top speed. The #1 cause of each of these issues is heavier suspended fuel gum and petroleum varnish that restricts fuel passageways. The most important thing Marine PRO does is liquefy and clear away sticky gum and varnish restrictions so the engine can go back to starting fast and running strong.

Hope that helps!

Thanks for the question!

The important thing is that the engine runs and uses up the treated fuel. Driving until almost empty with the Sea Foam-treated fuel lets you get the most out of a can of Sea Foam. We recommend driving for at least 10–20 miles before refueling. That gives the Sea Foam time to circulate and clean.

If you can’t drive it, let it idle for at least 10–15 minutes or so to start pulling the treated fuel through the system. On a small engine, you can let it idle for 10-15 minutes as well.

If you added Sea Foam to the oil, drive the vehicle 100–300 miles before your next oil change so the Sea Foam has time to circulate and reliquefy oil residues that will drain out with the old oil.