Motor Problem

[Lasty]

I have a 40hp Johnson (2 stroke) which only has 4 hours on it. When we were out today it started reving and racing like it had dropped out of gear and we lost power and then the power would return and we would surge ahead. When we got home and were flushing it it was idling really rough and then stalled.

I will be calling the dealer tomorrow but was wondering if anyone had any ideas what might be the problem?

[domza]

i used to get that problem on my boat. Although mine is over 20 years old, i can't see it being the same problem.

a simple tune of the carby fixed the problem.

i also got an increase in revs when i prime the bulb when the motor is running.

i would go straight back to your dealer and claim it on your warranty.

[Shark Bait]

When 2 strokes are starved of fuel their revs increase before they stop. Ever heard your 2 stroke mower run out of fuel. Ever disconnected the fuel tank from your 2 stroke outboard to run the carby dry for storage. They speed up just before they stop.

Next time it happens, it may be worth looking at your fuel supply. First up, while the motor is still running prime the motor with the primer bulb. If this helps, or the primer bulb feels flat when you squeeze it, your motor is starving for fuel. If this happens, try the following.

Loosen your fuel cap to make sure there isn't a vaccum in your fuel tank. If there is a vaccum, your fuel tank breather is blocked & your motor can't get fuel. I've left my breather screwed shut before. My fuel cap had a good seal so my motor eventually stopped.

Next up, check your fuel line isn't kinked. This has also caught me out.

Good Luck,

Rick.

[bisso]

When 2 strokes are starved of fuel their revs increase before they stop. Ever heard your 2 stroke mower run out of fuel. Ever disconnected the fuel tank from your 2 stroke outboard to run the carby dry for storage. They speed up just before they stop.

Next time it happens, it may be worth looking at your fuel supply. First up, while the motor is still running prime the motor with the primer bulb. If this helps, or the primer bulb feels flat when you squeeze it, your motor is starving for fuel. If this happens, try the following.

Loosen your fuel cap to make sure there isn't a vaccum in your fuel tank. If there is a vaccum, your fuel tank breather is blocked & your motor can't get fuel. I've left my breather screwed shut before. My fuel cap had a good seal so my motor eventually stopped.

Next up, check your fuel line isn't kinked. This has also caught me out.

Good Luck,

Rick.

i always thought that was the case with two strokes, however, i think the new models with direct oil injection dont do the same as the older premix models insofar as the higher revs before starving of fuel. i have a 2006 model two stroke and if i disconnect the fuel line in simply chugs until it runs out of fuel. (quite painful really). i would be definately taking it back to the dealer to be checked. another option is to get the dealer to come out on the water with you and see what is happening, it might be something very simple..... i have been through this one before, it was simply a loose carby linkage that you cant see at idle and it only occurred under load to the motor.... hope that helps.. cheers and good luck with it.

[Lasty]

It has been back to the dealer who says he tested the motor and there is nothing wrong with it. He said that the pertol tank cap prrobably has a really good seal and that I didn't loosen it enough. I am a bit sceptical as the time the fuel line was accidentially disconnected while flushing the motor it just purred until it stopped. I will be going out again later this week and time will tell, however I might flush it again before I go and see how it starts and idles from cold!

[SUFFO]

Try checking all your spark leads are connected firmly at the plug.It could be a loose connection on just one of them.

Cheers

Suffo.

[Lasty]

After being told by the dealer that there was nothing wrong with the motor and I just hadn't loosened the fuel cap it happened again.

I went out today and ensured that the fuel tank cap was very loose. The motor went fine early in the morning without being pushed but when the wind and waves came up every time I went over 3000 rpm the motor seemed to rev but we lost power. When I throttled it back the power came back. It was fine below 3000rpm but when I tried to take it over 3000rpm the motor increased to 4500 to 5000rpm and once it went from 3000rpm to 6000rpm wiothout any increase in power.

When this happened I checked the fuel lines and it all seemed OK. However I have noticed that the connection between the hose and tank seems a little loose and after it clicks in there seems to be about a 5mm gap. Also I connected the hose to the tank at home but when we reached the ramp it had come off. This happens regularly and I was wondering if that is where the air maybe getting into the system and starving the motor of fuel?

Anyone else got any other ideas as I don't want to take it back to the dealer again if it is something stupid that I am doing.