DT 140 -will not rev up and plain out- ok in idle tho

[Tcorbeil]

I have a 1986 DT140.

The motor fires up easy and idles perfectly. While it is out of gear I can rev it without any issue.

One I put it into gear and try to rev up the motor seems to bogg and not rev up... I was not even close to being able to plain out and I gave up and came back to the dock.

Motor is on a 15.8 bowrider so there is no issue on weight.

The motor was fogged through the winter..
So I am thinking possibly
1- The plugs are fouled??
2- The carbs needs cleaning ? ( high speed jet or something clogged?)


anyone have some thoughts?
The motor runs perfect idling in gear and out of gear.
I can rev the motor up while out of gear no problem.


Only issues is when the motor is underload and trying to accelerate.

Thankyou for any input. I do not have a ton of experience with outboards.. but have seen similar issues on my buddies boat and think it could have been foulled plugs..

Compression has been checked.. 135 -140 in all 4 cyls.
Brand new fuel was being ran out of a jerry can.. so no chance of sludge getting sucked up in old gas tank
Oil was older that was in tank.. Any chance of the oil getting sludged due to age?

Thanks in advance for your help

[Tcorbeil]

No one have any thoughts on this???

[blaze318]

similar issue

I bought my 1988 dt140 back in march. Ran great on muffs but crappy in water. Took it to repair shop had carbs rebuilt and cleaned worked ok after that but now having similar issues again already. They also had to put a new choke silenoid water pump and a plastic tube in the fuel pump. Now she is spitting and sputtering again and wont get speed. About to junk it I think.