2008 9.9 4 stroke

Forbsey10

Active Member
Need advise on a 2008 9.9 bigfoot merc
Starts fine idles fine but when you power up
it starts to run rough. Had a mechanic check
carb and spark most everything.
Any suggestions
 
It's not clear what you meant by checking the carb but I would clean the carb as that is a common solution to the problem you seem to be reporting. Here is a video on the steps needed if your handy with the wrenches.
 
Next I would confirm the fuel pump diaphragm. You could see excess fuel on the surface of the water if running in a pail. Even squeezing the prime bulb won't always confirm a bad pump. I've seen this stump a marine mechanic once. I ended up bypassing the fuel pump altogether, hooking the fuel line direct to carb after the filter (or however yours is set up) squeezing the ball while running made it run perfect.

Or plugged jet is the usual suspect...

Good luck!
 
Last edited:
Thanks for the reply i have cleaned the carb changed plugs filter
had a mechanic check the compression even he was stumped might try
by passing fuel pump see if that makes a difference
 
I have the same motor but it's a 2000, had some issues a couple years ago. Wasted money rebuilding the carb, didn't work, ended up buying a new carb which is what I should have done in the first place.
 
x2 on the just put a new carb on. WAYYYYY faster. I live down south and ordered mine online.
 
Anyone out there can find me a carburator
part #856919T2 or have any ideas what i can replace
it with. Hard to find seen one in the USA but won't ship
to canada
 
Anyone out there can find me a carburator
part #856919T2 or have any ideas what i can replace
it with. Hard to find seen one in the USA but won't ship
to canada

https://www.boats.net/catalog/mercu...u-1b226999-usa-cat-90-803183-323cc/carburetor

Boats.net is easy to deal with and they ship to Canada. The Carb you're after is in stock. Its the last Carb listed under description #1. $267.58 USD.

Heres the link with a photo..
https://www.boats.net/product/mercury/856919T2?ref=43564bcb69bb7381562a7cbfda81e7ab71791016
 
2 years ago I was getting ready for my trip to Port Renfrew and started my 9.9 yamaha and it would not run good at higher throttle. I called the dealer and asked if he could get me in to look at it and he was swamped. He told me if I would remove it and take it to him, he would put it in the vibrating cleaning wash over night and it should fix my problem. I did and it did fix the problem. Just thought it might be something you could consider.
 
Thanks tried everything mechanic thinks thats the problem
Cleaned it and ran seafoam thru it doesn't make a difference
 
Thanks but tried to buy from them and told me only sell in the USA

That’s bizarre. Maybe it has something to do with Mercury parts. I’ve ordered thousands of dollars of Yamaha parts through them and never had an issue. Another way around the shipping issue would be to get it shipped to a postal service in Blaine, WA. I use 5D parcels and it couldn’t be easier. $2 to hold your package, quick and easy pickup.
 
When I had a mercury it never took weeks to get parts through the local dealer. Usually a day or two. Prices were not very good, but by the time you add shipping from the us, duty taxes etc and only having too wait a couple days instead of a couple weeks it was worth it.
 
Need advise on a 2008 9.9 bigfoot merc
Starts fine idles fine but when you power up
it starts to run rough. Had a mechanic check
carb and spark most everything.
Any suggestions
Few years ago a guy told me about a product recommended to him by a small engine mechanic, its called Star Tron. I get it a Canadian Tire in the marine section, its a fuel stabilizer as well as a cleaner. I use it in every small motor I have and it works great. All these newer motors have super small jets and even a tiny spec buggers things up. This stuff works great can’t recommend it enough. I’d give it a try for sure.
 
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