Old Outboard Engine Help

[racer2c]

I’ve been helping my sister and her boyfriend troubleshoot an issue they are having with their old 4 cylinder outboard. The engine starts and idles great in and out of the water but underway once on plane it will lose power and stall after about 30 seconds. It always starts right back up again and idles fine.

So, my shadetree mechanic instincts tell me to have them first rebuild the carbs. This engine is 30 years old and they got it from a guy who had it sitting in a field for the last 5 years. Boyfriend put new plugs in and replaced all the fuel lines. He did tell me that they had an issue with the tank vent but he didn’t articulate what exactly that problem is. After doing some reading around the web I’m going to have him check the primer bulb when it stalls to see if it is hard. I’ve read that air getting into the system will cause this problem or also indicate a fuel pump problem although it has no problem with full throttle on earmuffs.

Fuel filters, plugs, starter solenoid, and all fuel lines have been replaced.

Besides rebuilding the carbs and checking the primer bulb, any other suggestions?

[seapuppy]

ok..if you haven't checked the tank....there is a screen at the pickup that gets crapped up...it will allow the engine to run all the way up to red line with no load ...but start drawing a load on it and it will definitely stall....so...if you have replaced the fuel filter...(hopefully it's an inline filter)...then it has to be either the bulb cracked or the pickup in the tank itself....


had something similar to that happen on my boat...a small piece of junk would block the inline filter.....when I would fall off plane and drop the throttle to idle...it would idle fine..run up to about 4k rpm and then stall...replaced the filter...boat and engine has ran fine ever since....
another thought is you may have a bad filter...manufactured wrong from the get go...check it out..

SP.

[racer2c]

Thanks SP!

The more I think about it, the more I think it is a fuel filter/bulb/pickup issue.