9.9 Mercury Troubles

Riggen&Jiggen

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So I have a 2015 9.9 Mercury pro kicker and I have had troubles with it for about 2 years now. I brought it in a couple of times and they say the jets were gummed up and that I need to run it out of gas each time after using it so it does not happen. Well I thought that was bullshit. You should not have to do that during the summer. I started having issues again this summer. At home I put the muffs on it and tried to start it with out the fuel line plugged into the motor. It started right up and ran flawlessly. So I plugged the fuel line in to run it longer. As soon as I plugged in the fuel line it started to sputter and quit. I could not get it to stay running. So I unplugged the fuel line and after a few trys it started to run again. So I let it run until it ran out of fuel. I plugged the fuel line back in and started it but same shit. So unplugged it and wouldn't you know it ran perfect. After a minute I plugged the line back in and finally it stayed running. I left it on for about a 1/2 hour with no issues. Get to the lake this weekend and same issues. So I replaced the buld and the fuel line connector thinking it was getting air or something. That has not fixed the issue. Anyone have this happen before? What the hell is going on? It seems that to have it run I have to unplug the fuel line, let it warm up and then plug the line back in and it will run fine.
 


reddevilwoodsman

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Some of the symptoms sound a lot like the symptoms of a plugged fuel vent. How is your fuel line plumbed? Does it go directly to the tank or is it tee'd into the main motor gas line?
I have a 2011 9.9 Pro Kicker and when it was brand new, it was very touchy. I ended up taking the carb apart and cleaning it but I had to do that only once or twice in the first season that I had it. It's worked fine since. I've read all of the things about you have to run them out of gas, etc., but I have never done that and it's ran perfectly since 2011 when it was brand new. I thought having to run them empty of gas after each use was B.S. too. I add Mercury fuel conditioner every time I fill gas, add STA-BIL and run it through prior to storage every winter. I don't even run it out of gas prior to winter storage and it always takes right off every spring.
 

Riggen&Jiggen

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Planning on opening the back of the boat up to look where the line comes from the gas tank. 1 gas tank supplies gas for both the big motor and kicker. What puzzles me is why does it run great at all if it is something to do with the carb? I had them go over the carb twice in the past. My hunch it is not carb related. I always put seafoam in with the gas and always use 91 oct. with no ethanol.
 

riverview

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they told you to unplug the fuel line and run the carb out of gas so there isn't any fuel to dry out in the jets (which are very small on a 9.9) you shouldn't be running ethanol in your outboards anyway so you shouldn't have to run it out of fuel every time you run it. Not a bad idea the last tiem you run it in the fall though. I tell people to run the fuel out of all there small engines if possible. It solves a lot of carb problems. sounds to me like you have a float needle valve sticking open and when you plug the gas tank in the motor floods out. I would get a new needle and seat and clean the carb.
 

eyexer

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it's not your carb. you may have an obstruction in your primer bulb or something just isn't right with that. I'd throw on a new primer bulb first. If your main motor shares the same tank and runs fine the vent isn't the issue either. Is there a valve you have to switch from main motor to aux motor by chance?
 


wslayer

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I think riverview has it pegged. Happened to mine a few years ago. Had to clean carb completely.
 

Sum1

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With ours the big motor ran like shit when Moritz added the kicker. Russ added a fuel shut off valve going to the kicker and both engines now run great. When you go back and forth between engines you get air in the lines or something I can’t remember what it was. Call Russy baby booby at boat works, explain what is happening and he’ll tell you how to fix it instead of speculating. Save yourself time and money.
 

eyexer

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If you want go keep troubleshooting it go buy a clear bodied fuel filter and install it after the primer on fuel line. Then run it and see if the fuel supply is good
 

WormWiggler

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With ours the big motor ran like shit when Moritz added the kicker. Russ added a fuel shut off valve going to the kicker and both engines now run great. When you go back and forth between engines you get air in the lines or something I can’t remember what it was. Call Russy baby booby at boat works, explain what is happening and he’ll tell you how to fix it instead of speculating. Save yourself time and money.

Russy baby booby this thread got creepy quick
 


SDMF

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I think those have a foam air cleaner under the hood, check that if you've been trailering on gravel.

If you're flooding by attaching the line, could be due to restricted airflow through the foam filter. Just a thought on a potential simple fix.
 
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Green19

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I feel your pain RigJig, I know your pain. Brand new 2017 9.9 Pro-kicker. Yes it professionally kicked my ass from first day out. I went through hell and back in into Hades again figuring this out. Similar symptoms with mine but there were too many things that happened along the way with the three repair shops to figure out what happened, if anything, at the factory. I seriously wanted to rip the thing off and dump it to the depths of hell. A year and a half of trying this and trying that.

A couple things I learned in the process.
1. There isn't a need to drain the carb of fuel during the season. I got different reports on doing this or not doing this from dealers and buddies. I don't do it anymore until end of season, which is never for me it seems.
2. If there is gas in the oil(you can smell it), you have other issues. Take a look at the fuel pump. This was the clincher problem for me. Once this was done the little fierce kicker ran like a kitten. After all the carb repairs and needle replacements and all the other BS, it was the fuel pump.
3. Ran like a kitten until after about 20 hours. Then it started running like crap again. So I changed the oil and plugs every 20 to 25 hours of use. I thought I was going to have to live with this. But my buddy has the same motor and year and his ran like a dream from day one. Never had to mess with his all season long. I got a motor that was demon spawn. Until...
4. I got this tip from a tech in Fargo, I strongly suggest removing the fuel line at the end of each day on the water. I just put the provided rubber motor fuel line (male) on and wrap the connector (female) with a dog poopie bag and rubber band it so it stays clean and dust free. Why? because if the gas vent isn't working the expansion pressure will push gas into the carb and excess gas will find its way to the oil.
5. Since this tech fellow told me this tip, I can run this thing for months now! (unless I forget to disconnect the fuel line)

So after several trips to various shops trying to isolate the problem it basically was the fuel pump and venting not working like it should. All but one of these trips were under warranty. Mercury would not warranty that one for some reason.

Now to figure out why my gas vent isn't working like it should.
 


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