run on

[mecanik1975]

2007 tahoe q4 with 4.3 liter…after cruising the lake at any speed for any length of time…engine will “diesel” unless allowed to idle for at least a minute???

 

[Scott Danforth]

check your timing
check your carb if you are running rich

 

[QBhoy]

This can happen if the fuel isn’t in great shape

 

[achris]

2007 tahoe q4 with 4.3 liter…after cruising the lake at any speed for any length of time…engine will “diesel” unless allowed to idle for at least a minute???

Allowing a minute or so after a hard run (for the engine to 'wash off' extra heat) is Merc's recommended fix for run on. My dealership spent DAYS with the Merc specialists both in this country and at head office in FonDaLac trying to solve this run on issue. Even to the point of programming up a new TB-V module and having it flown directly to us... They also produced a special kit for the carb that closed it even tighter when the key was turned off... We pulled heads off looking for carbon deposits, we had valve guides machined to decrease friction. Nothing helped, so they just instructed that owners be aware of the issue, and allow a minute or so for the engine to cool before shutting down...

Chris...

 

[mecanik1975]

Allowing a minute or so after a hard run (for the engine to 'wash off' extra heat) is Merc's recommended fix for run on. My dealership spent DAYS with the Merc specialists both in this country and at head office in FonDaLac trying to solve this run on issue. Even to the point of programming up a new TB-V module and having it flown directly to us... They also produced a special kit for the carb that closed it even tighter when the key was turned off... We pulled heads off looking for carbon deposits, we had valve guides machines to decrease friction. Nothing helped, so they just instructed that owners be aware of the issue, and allow a minute or so for the engine to cool before shutting down...

Chris...

believe it or not, that sounds reasonable…BUT its scary while trying to pick up a down skier when the engine wont shut off. lol

 

[achris]

believe it or not, that sounds reasonable…BUT its scary while trying to pick up a down skier when the engine wont shut off. lol

I hear this a lot... I guess in the early days when control boxes didn't have an interlock mechanism, then the lever could be accidentally bumped into gear, that's a fair call. Shutting the engine off gave a level of safety, but not now, not with an interlock on the control box. It is IMPOSSIBLE for the lever to be accidently bumped into gear. Just pull it into neutral and get your skier aboard. Whatsmore, the driver shouldn't be leaving the helm anyway, so the risk of the lever being knocked should be zero...

As I say, don't shut the engine off while picking up skiers, it's completely unnecessary!

Chris...

 

[Scott Danforth]

key off in gear will kill the motor and not run-on.

 

[achris]

key off in gear will kill the motor and not run-on.

Not always... I've seen boats keep running on while in gear...