Hello, I have a 2000 Tohatsu M40C I have fixed a couple problems on but still has an issue that I'm trying to figure out.
When running on muffs or in a 50 gal barrel it will start and idle smoothly in neutral or forward gear all day.
When I take it take it out on the lake it does good, runs smooth, goes about 32mph (GPS) at WOT...but after running wide open for about 4-5 minutes it starts surging/cutting out, and usually gets progressively worse until it dies completely. If started back up immediately it will idle roughly and try to die. Once you get it back going it will run ok and if you run it about half throttle it will not have issues but if you run it back wide open it will start surging again after a few minutes.
A little background:
Compression checks good with engine cold AND with engine warm.
I have replaced the water pump housing and impeller (it needed that anyway).
Temperature tested the thermostat.
Has good stream of water from the indicator and water coming out of exhaust idle relief ports.
After running WOT for several minutes you can hold your hand on the head for several seconds so it is not overheating.
Replaced the complete carburetor assembly because I found one of the ears that hold the pin for the float was broken off.
Have had the prop refurbished / repaired at a prop repair shop.
Any ideas of where I need to go with this? I'm thinking that the fuel pump could be having problems possibly or maybe the coils are heating up and then cutting out... not sure if either of these would be a common problem?
When running on muffs or in a 50 gal barrel it will start and idle smoothly in neutral or forward gear all day.
When I take it take it out on the lake it does good, runs smooth, goes about 32mph (GPS) at WOT...but after running wide open for about 4-5 minutes it starts surging/cutting out, and usually gets progressively worse until it dies completely. If started back up immediately it will idle roughly and try to die. Once you get it back going it will run ok and if you run it about half throttle it will not have issues but if you run it back wide open it will start surging again after a few minutes.
A little background:
Compression checks good with engine cold AND with engine warm.
I have replaced the water pump housing and impeller (it needed that anyway).
Temperature tested the thermostat.
Has good stream of water from the indicator and water coming out of exhaust idle relief ports.
After running WOT for several minutes you can hold your hand on the head for several seconds so it is not overheating.
Replaced the complete carburetor assembly because I found one of the ears that hold the pin for the float was broken off.
Have had the prop refurbished / repaired at a prop repair shop.
Any ideas of where I need to go with this? I'm thinking that the fuel pump could be having problems possibly or maybe the coils are heating up and then cutting out... not sure if either of these would be a common problem?