Engine dies at WOT

[lockieboi]

15 HP Johnson - YouTube

Filmed on a Phone so not the best quality.

Any thoughts on the problem welcome

The fuel line has been checked from the intake to the carb and the carb cleaned.

Thanks for your help

[Peter_C]

Sure sounds like a fuel related problem with the way it slowly dies. An electrical fault will typically shut it down right now, like pulling the kill switch. Run it full throttle and pull the kill switch and you can see if it sounds different. I wished you would have kept recording for another 30 seconds. How did it recover once restarted? Could you try priming the fuel bulb right as it is dying? Looking for maybe an air leak or a defective fuel pump. Leaning towards the defective fuel pump, but there are still tests to perform.

[lockieboi]

Originally Posted by Peter_C

Sure sounds like a fuel related problem with the way it slowly dies. An electrical fault will typically shut it down right now, like pulling the kill switch. Run it full throttle and pull the kill switch and you can see if it sounds different. I wished you would have kept recording for another 30 seconds. How did it recover once restarted? Could you try priming the fuel bulb right as it is dying? Looking for maybe an air leak or a defective fuel pump. Leaning towards the defective fuel pump, but there are still tests to perform.

Thanks for your reply.

I've pulled the kill cord at WOT this morning and it dies straight away so yes it's a different sound.

[batfalcon]

Do you have normal running temperature at the engine? You can check it if you put your hand under the indicator and feel the temp of the outgoing water.
First of all, is there any water pumping out from the indicator?
And second, do you feel it extremely hot, or not?

After she died, I saw that she started right up. Did she run smoothly and died at the wot a few minutes later, or she couldn't idle at all?

[lockieboi]

The water coming out the tell is hot and the leg is also hot but I'm told this is normal?

After it starts again it will continue to run at WOT for another couple of mins before cutting out.

It is fine at 3/4 throttle.

[Peter_C]

Do you have a another fuel line and fuel tank you could try? From the fuel tank, all the way to the motor connection, reuse nothing.

At this point I would tear the carb down and throw it in my ultrasonic cleaner and blow all the ports out. Put it back together and run it again. Could be something intermittently getting into one of the jets, or something strange like the float getting stuck, in the up position (Never seen that before).

If it were me and I exhausted all other tests I could think of, I would replace the fuel pump. The issue is caused by fuel starvation, and there is not a lot on a motor that small to cause this issue.

[batfalcon]

Originally Posted by lockieboi

The water coming out the tell is hot and the leg is also hot but I'm told this is normal?

After it starts again it will continue to run at WOT for another couple of mins before cutting out.

It is fine at 3/4 throttle.

Water must have a temp that your hand can stand. Not above 45 C. The leg will be a little hotter than this.

I an thinking of 2 possible reasons:
1. What Peter C describes. For some reason fuel is not enough at wot.
2. If the engine has some electronic device and runs too hot, then possibly some command is given to reduce the rpm or even to slow her down to 0, in order to avoid any damage.

Finally make the following:
At the very instant that she reduces rpm, cut the throttle to half. What happens then?

[Peter_C]

Have you tried the propane injection for a few seconds while it is dying? Use a torch (Not lit DUH!) or the hose part from a camp cooking stove or whatever you can rig up to add a "little" propane as it is dying. This confirms fuel, which also rules out an overheat circuit. You could also get your buddy to prime the fuel system as it is dying.

There have been some good ideas thrown out, now go test them and report back to us.

[lockieboi]

Originally Posted by Peter_C

There have been some good ideas thrown out, now go test them and report back to us.

Thanks for all the help, I will try what's been advised.

[actions]

Whitstable marine have always been very good to me and even had the mechanic come out with me when i had a problem with a previous engine. Id pop back and tell them you still have a problem and Im sure they will help all they can especially if you've already paid and its still not right. if you can speak direct to the mechanics as its always easier to explain direct.

Sent from me!