2006 mercury 9.9 just will not stay running

[markpatrick]

Every year this motor has been great. this year it just will not run. It started by running poorly and only running when choked. I brought it in to the shop and they told me there was water in the gas. They took the carb off and cleaned it out and said that I was good to go. I brought it to the marina got out away from the boat and it died. would not restart. Towed it in and tried round 2. Now it would only run with the primer ball. after that fuel was burnt the engine would shut off. I brought it back to the shop and they told me that the fuel line had failed (the one off the tank). I had that replaced. They test ran the motor and said that it was good to go. I picked it up and brought it back to the marina. 2nd pull it started and ran great. Revved the motor and it responded well. While running noticed that there was a lot of either oil or gas in the water...not sure if just residual from oil that spilled out of the motor. After about 10 minutes the motor stalled. it would not restart. I left it alone and tried it next day. 1st pull it started and did the same thing. I am just at a loss.....

[matth121]

after your 2nd trip to the shop, and it stalls after 10 mins- did pumping the primer bulb help? I'm gonna guess that it didnt. is there any fuel inside your cowl? maybe its dripping from a line, although you think the shop would have seen that. Is it pumping water ok, not overheating? Again, if they tested it, they should have noticed if this was the case. I'd bring it in once more, and if theyre any kind of decent guys, they should be willing to test it again for free since I'm sure youve paid them twice already and they keep telling you that its good to go, but obviously isnt. Best of luck

[markpatrick]

I have not noticed any fuel in the cowl area. I went down to the boat last night. I started the motor again and it ran great for about 10 minutes. I put it in gear and put a load and no issues. Then it just stalled again and would not restart......very odd. It is pumping plenty of water and the oil level is good. I still have to get it back to the shop I just havent had the time. Luckily last night I resisted taking a ride. It fools you because it runs no perfectly right until it shuts off. when it does shut off hitting the primer ball does not make a difference. The ball on the fuel line is still hard

[Texasmark]

You may not be chasing a fuel problem. Ignition coils have failed me in much the same manner as you describe your problem. Not saying that you didn't have fuel problems, but you could have had 2 issues. Possibly you got the fuel issue solved and now the (possible) ignition problem surfaces.

Thinking about what I said, that 9.9 probably has 2 cylinders and 2 pulse packs so the loss of a coil would shut down one cylinder not both....however triggers coming from electronic circuits could, or under your flywheel, your stator, being a magnetic device might also.

Buttt fuel affects both and it could still be a fuel problem. The reason I personally wouldn't be chasing fuel on where you are now, is that 10 minutes running under load seems that the engine is ok.....another thought. If your fuel tank vent is not working properly, 10 minutes of running could produce enough vacuum to keep your fuel pump from being able to pump adequate fuel to keep the engine running. Over time, what venting there is, has time to allow the tank pressure to stabilize and you get another 10 minute run. Just loosen, or remove your tank fill cap (if safe to remove) and see if you solve the problem. The vent hole in the fill cap is pretty small and can get clogged easily......I had one on my riding lawn mower using a plastic tank and it sucked the tank into a wad Ha!...so I know it can happen.

HTH

Mark

[CharlieB]

Is this a 4 stroke?

Have you checked the oil level?

A bad diaphragm in the fuel pump will fill the crankcase with gas, flooding the motor in a short time.

[markpatrick]

Very interesting with the possible ign problem. The fuel vent is working. I did try to take the cap off just to make sure that did not make a difference. As you mentioned with the coil if one shut down it would seem like it would still run. I just dont know what to do to test the other items? When it is running it runs strong.......good times! any suggestions on what I could do to test next?

[bluebear57]

i had a very similar prob with my out board for months, i checked fuel pump,carbs,fueltanks,wiring plugs etc. and finally found out by testing all ele componates that ths trigger and stator were defective replaced them prob solved there is a way to test them hav e your mechanics might be the answer lonnie

[Texasmark]

I had a CD Module with a thermal problem once. It failed when cold, but after the engine warmed up somewhat (running on the other two cylinders) it started working and worked fine the remainder of the outing. I thought I just had a cold natured engine till one day I decided to do an electrical test when I was at home and the engine hadn't been operated and found it.

Yours may be just the opposite. Maybe you could make electrical tests on your electric/electronic components and then run your engine on muffs till it quits, then run the tests again and compare data.

Mark