1998 Mercury 135XL dies at idle speed

Repair or modification of Boston Whaler boats, their engines, trailers, and gear
JimL
Posts: 1
Joined: Sun May 07, 2023 12:31 pm

1998 Mercury 135XL dies at idle speed

Postby JimL » Sun May 07, 2023 2:19 pm

My 1998 Mercury 135HP 6 cylinder engine runs fine at higher RPM but dies when brought back to idle. Launched the boat yesterday and ran it at 2500 RPM for about 20 minutes before pulling back to idle. It ran for about 2 minutes at 800 RPM before slowly decreasing to below 600 RPMs sputtering and dying. Despite being warmed up, it wouldn’t start back up until I let it sit for a couple minutes and heavily reprimed but it still wouldn’t run at idle.

Just had the boat in over the winter for replacement of the infamous plastic drive gear for the oil injection system. Any thoughts on likely cause of problem?

msteinkampf
Posts: 37
Joined: Tue Nov 15, 2022 4:05 pm
Location: Alabama/Louisiana

Re: 1998 Mercury 135XL dies at idle speed

Postby msteinkampf » Mon May 29, 2023 9:53 am

Is this the carburetor version or the direct fuel injection (OptiMax) model? My review of the parts list on Crowley Marine indicate that both models were available in 1998.

M
1990 Montauk 17’ w 1991 Mercury 90 HP outboard
1995 Aquasport Explorer 245 w twin 1995 Yamaha 150 HP outboards

MarkCz
Posts: 131
Joined: Sat Jan 27, 2018 3:44 pm

Re: 1998 Mercury 135XL dies at idle speed

Postby MarkCz » Tue May 30, 2023 4:14 pm

How old is the gasoline fuel in the fuel tank?