Won't start when trimmed up

[T-Bone]

I have a 1992 115hp Mercury. I have run this motor hard for 17 years and never had any major problems or shop time. Change water pump, plugs regulary and put a starter on about eight years ago. Last year it would not start unless the motor was trimmed all the way down. The motor would turn over fine and as soon as I trimmed it down it would start. Any ideas what the cause would be and the fix?

[Hot Runr Guy]

I had an old V-6 OMC that was the same way, my guess is that the carb floats won't let the needle & seat properly seal at that angle, so maybe the carbs are flooding. Just for kicks, when it's tilted-up, will the primer bulb stay hard?
HRG

[T-Bone]

The boat is in the garage waiting for soft water. Never thought about checking the ball firmness, that'll have to wait til March. Any body have any idea the cost to rebuild the carbs. The motor runs fine, just that little quirk that is sometimes irritating.

[scl73]

I had a V4 115hp Johnson that did the exact same thing and it was the float. Not sure on the price, I had a friend fix mine.

[yarcraft91]

Sounds like this is a recent problem in a motor you've had for a long time, so it's a maintenance, not design, issue. Before you have someone rebuild the carbs, run the Seafoam shock treatment on the engine and see if that corrects the behavior. It will not harm the motor, will de-carbon the engine and clean the fuel system. I do this annually on my small gas engines.

One of many places describing the Seafoam shock treatment:
http://www.tx.rodngun.com/forum/topic.asp?whichpage=1&TOPIC_ID=14931𚌍

[TomP.]

At that age I would also look at the wiring may have a frayd wire that is grounding or broken in the starting system. When the motor tilted down making contact and up loose contact. Like a neutral start wire etc.

[ffishman]

I have a 96 150hp Merc. Mine has been like that since the day I bought it.

[larrym]

I owned a 2000 125 at one time and, like ffishman, mine did that from the time it was new. I experienced it the first time I started it at the boat ramp and another boater said I needed to have the motor level. When I did it started at once and my dealer later confimed that was true. Another in our group now has one and has the same experience. Once started they of course will run fine when tilted.

[T Mac]

None of the carbed model outboards like to start when tilted up.
But... you may want to run some Yamaha "ring free" through the motor... you may not be getting as much compression as you used to...so it it isn't drawing air and fuel across the cylinders as well is it could.
Try the "shock" treatment.

[T-Bone]

I have been using seafoam in my fuel for two years now, never tried the shock treatment. Guess I'll try the ring-free and then the shock treatment when spring comes and see what happens. In years past when changing spots I would accidently start the motor trimmed up and rush to trim it down. Thanks for the ideas, I can live with it but sometimes it's annoying.