Motor shuts off underload

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FishingFreak13
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Motor shuts off underload

Post by FishingFreak13 »

Before the end of the season last year I purchased a used 2001 Merc opti 135. The dealer i took it to ran it on the muffs and checked it out and everything was fine. When I took it out on the water the next weekend it would turn on first turn every time which is good. They told me to let it idle for a good 10 minutes since it had been sitting for a while. After doing that I proceed to go up on plane and the motor would shut off almost like it was bogging down. After trying it a few more times I gave up and put the boat back on the trailer. By this time it was to late in the season to take it back and have it looked at. Before i take it in this spring I was wondering if anyone has had an issue like this before. When i pulled the plugs to winterize it they were charcoal black so i figured that isn't good and have new ones to put in in the spring (ill get the shop to do it because mercury seems to love putting the bottom plugs in impossible spots). Seeing as it is probably more than just old plugs I'm thinking that it might not be getting enough fuel that it needs when its under load. Just wondering if anyone has had this happen before or has any insights on what the problem(s) might be before I take it in.

Thanks, Brian
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Lvace
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Re: Motor shuts off underload

Post by Lvace »

my guess after seeing the same thing happen to 25hp yamaha is fuel starvation issue. The carb was removed and cleaned and the motor ran perfect after that! The yamaha had sat in a basement for 10 years give or take!
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Yakster
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Re: Motor shuts off underload

Post by Yakster »

dirty carbs or air being pulled in.
Check fuel lines for any cracks and ends are tight on the barbs.
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Troutskiii
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Re: Motor shuts off underload

Post by Troutskiii »

My little Honda outboard has an identical issue, it will idle all day long, in a barell it will throttle up without issues but as soon as load is put on it starts to stutter and bog.

Chased the issue last summer, buddy of mine replaced and serviced fuel system still does it.

I hope you figure it out, nothing more annoying then a motor not running how it should. What area are you in? Could maybe recommend a marine mech depending.


Cheers,
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CNs
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Re: Motor shuts off underload

Post by CNs »

Run some seafoam or quickleen through the motor . Follow directions about the amount.
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jjcanoe
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Re: Motor shuts off underload

Post by jjcanoe »

Had a pair of similar situations a few years ago,
1. fuel tank not full, the hose inside the fuel tank was towards the front, so when I had the bow up in the air a bit it would suck air, ran fine when the boat was more or less level
2. fuel tank full, had some wear on the connection where the fuel line connected to the motor and it, again, was sucking air. It was fine at idle or trolling speeds, however when the motor throttles up the suction was enough to compromise the seal and grab some extra air, shutting it down
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So long, and thanks for all the fish.
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scarkner
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Re: Motor shuts off underload

Post by scarkner »

CN wrote:Run some seafoam or quickleen through the motor . Follow directions about the amount.
X 2!!!

Seafoam is magic.

I had a really dirty engine a few years ago I bought used. I put it in as strong as I could and let it sit for a short time. The way I do it is to fill the external gas-line with it (by opening the drains on the carbs and using the primer bulb in the gas line to draw it into the carbs (with the gas line disconnected from the tank and inserted in the seafoam which was in an empty gas can). I then turned over the engine (without starting) and let it sit for about 15 minutes. I had mixed the rest of the can into the regular gas, started the engine up. This might not work for you, you should probably just follow the directions... but I am not a "directions" kinda guy.

You could actually hear when the jets cleaned out. The engine went from a rough idle to smooth and throttled up great. It was like a performance on/off switch.
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Daboss
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Re: Motor shuts off underload

Post by Daboss »

X3!
Damn right I'm good in the sack...I can sleep for hours!
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