carb troubles?

[myfirstboat1984]

My boat has been trying to quit on me when under heavy stress, but I have been purposely not pushing it hard, to avoid the problem. The engine starts to die. It sounds like it just stops firing. If I back off on the throttle and slow down, I can usually keep it running, and most of the time, ramp back up to an acceptable speed.

This weekend, it got worse, and the engine started wanting to quit at lower and lower rpms/load, and even at idle. It was running so bad, I brought it into the marina. I got a tip from a guy at the marina to try a can of carb cleaner/tune up. As the can instructed, I sprayed it into the carb while it ran. I emptied the entire can into it, white smoke coming out the exaust and all, and then shut off the engine for 30 minutes.

After that, we took it out and it ran better than it had ever before. It had better pick up, horse power, and did not bog down, even under the heaviest stress I could put it under. I was so surprised. It did good like that for about 3 hours. Then, the old symptoms came back.

Any clues as to what could be going on here?

Thanks!

 

[myfirstboat1984]

Re: carb troubles?

Diagnosed the problem as a carb issue. Sprayed cleaner around the outside of the carb and got some changes in the idle, signaling some kind of gasket leak.

Went ahead and did a carb rebuild. Took time, but only $25 in parts. It was in bad shape. Half the gaskets were completely corroded away and the needle was sticking pretty bad.

Took her out on the lake yesterday and she's purring now.

 

[Bondo]

Re: carb troubles?

It was in bad shape.

Ayuh,... No Surpise,... Glad to hear you've got it sorted out...

 

[myfirstboat1984]

Re: carb troubles?

I am a little embarrassed, but I posted a success too soon. I have to add some bad news to the results of the carb rebuild. She really IS purring now. The idle is much smoother and she's sounding better. Improved horsepower, and so on. So, the rebuild was a success.

I guess I didn't want to push her too hard the first time back out, but when I started doing that more today, I rediscovered the initial problem. While under higher rpm, WOT, heavy load, the engine rpms fluctuated up and down, engine stopped firing smooth, and if I don't let off the throttle, it dies.

I was starting to analysis fuel delivery, when I got sidetracked by the carb rebuild. So I will continue with troubleshooting and try to find the issue. Next up, fuel pressure test.

Still confused as to why the can of carb/engine tune-up spray caused it to run so great for a while the other day. Maybe just unrelated. Maybe a combo of problems!