120 mercruiser bogs out after 10 min. please help

[stillstrokin10$$]

I have a mercruiser 120 that bogs out when i reach high rpm or when the engine has been running for about 10 minutes. I replaced the carb, fuel filter, flame arrestor, fuel, and pretty much anything fuel related. It really seemed to me that i had a fuel problem but i guess not. I am stumped. It also wants to bog out when i get out of idle but it goes back to normal when i do get out of idle . I have new spark plugs, oil and oil filter, distributer cap, rebuilt outdrive, new fuel lines, new exhaust manifold , new starter and alternator.
It seems like when i bog out on the lake and let the engine sit for 30 minutes it will give me about another ten minutes of 4,000 rpm use before it bogs down again. If i only let it sit for a few minutes it wont run much past idle speed. The temp is good and it doesnt run to hot . can anyone help with my problem. Thanks for reading

 

[v8power]

Re: 120 mercruiser bogs out after 10 min. please help

I know they are no where near the same thing but, I had a waverunner that did the exact same thing. The fuel tank was not venting properly and was creating a vacuum in the tank. loosen the fuel cap when it bogs down and see if it hisses or sucks in a bunch of air when you crack it open. or look at the fuel tank and see if it is collapsing. (if you can get to the tank)

Good luck.

 

[cr2k]

Re: 120 mercruiser bogs out after 10 min. please help

Check to see if your coil is heating up too. Distributor wire goes to the - terminal. I have seen coils hooked up backwards work like you mention.. they get hot and quit.

 

[Bondo]

Re: 120 mercruiser bogs out after 10 min. please help

Ayuh,.. The Dying after 10 minutes sounds like a tank venting issue...
The Bog coming off idle is a Carb issue...