86 Johnson 150 dies under load

[bugeyedmuleskinner]

Help! my '86 Johnson 150 has started dying at high speed. I can pull it out of the hole and it will run for 400yds but then it dies. I can keep it running if I hit the electric choke, barely. Starts fine and runs good when not engaged. I cleaned the carbs, didn't fix it. The fuel pumps only 2 years old so I wouldn't think its bad. Any ideas?

 

[HighTrim]

Re: 86 Johnson 150 dies under load

Welcome to iboats.

The fact that it smoothes out when you choke it indicates that the high speed jets have crap in em. Did you remove them, and fully clean them, during the carb cleaning and rebuild? If not, I would do it again. You will need a specially made tool for removing the jets. Pic is compliments of FR.



Other things to look at are the fuel tank vent and the anti syphon valve, they are notorious for sticking in a semi closed position. Also ensure that there are no air leaks in the fuel line, and all connections are tight.

 

[emdsapmgr]

Re: 86 Johnson 150 dies under load

Your engine may be using more fuel than the fuel system can deliver. It runs just long enough, till the bowls run out of fuel, then it slows. As High Trim mentioned, it could be a weak fuel pump, fuel air leak, line restriction, bad anti-siphon valve, etc. Insufficient fuel flow for sustained high speed. Try pumping the fuel line as it gets ready to slow down. See if it will keep running full speed.

 

[bugeyedmuleskinner]

Re: 86 Johnson 150 dies under load

I'll start with the carbs again and go from there. The removal tool pics were great. Appreciate the hints. BMS