Engine Dieseling

My engine is a 4.3L Volvo carbed.

I have noticed some serious dieseling on my engine after stretches of watersports such as pulling tubers behind my boat. When I go to shut off my boat, it diesels for up to 10 seconds after I shut it off.

The manual calls for 87 octane fuel.

I have noticed that it helps when I run premium fuel (92 octane) instead of the recommended 87 octane.

It also helps when I idle the boat for a couple minutes after pulling riders.

The problem I have with relying on idling the boat to minimize dieseling is that when I am circling back to pick up lost tubers or wakeboarders, I like to shut the engine off as I near them for safety reasons. It's just not feasible to sit there in the water and idle for 3 minutes before I collect the riders.

I was going to try running a bottle of Seafoam through the fuel and/or maybe adding some octane boost to the fuel when I am using 87 octane.

Anyone have and experience with this type of thing?

Re: Engine Dieseling

its recommended to idle it a bit before shutting it off.

dieseling is somewhat normal in many boats used for watersports. I used to shut off in gear