Merc hard start and idle problems

[Diane]

Hi guys. I finally got my 76 Trimate II in the water and now my parade of questions begins!

I've got a 1985 3cyl 2 stroke 115 hp Merc outboard.

The first time I tried to start the motor it started only if I had the throttle advanced and sprayed starting fluid into it.

Ran it for a bit and then took it out and revved up and varied the speed and all was well until I brought it down close to neutral. It cut out at low idle but started up again two out of three times. Still preferred starting with the throttle advanced though.

Next day I went back to the slip and tried again and it was almost impossible to start. Several tries later with throttle advanced and starting fluid and it finally caught. Same problem but once it died down at low idle, I could only get it started after about five tried.

Choke seems to work.. I see and hear it. The carbs are newly rebuilt. Gas/oil mix is new. Plugs look clean.

I just bought the SELOC repair manual.

So any ideas of how to get this motor starting more easily and running better at low idle?

Oh... I love the mate. Gets up on plane in no time and is absolutely fun.

Thanks for any help.

Diane
Ithaca, NY

[Chris E]

Are you sure it's a 3 cylinder 1985 merc 115?
If i'm not mistaking, mercury has never built a 3 cylinder 115, either 4 cyl or the "tower of power" 6 cyl only. If the engine is an 85, then it's probably a 6 and if it is - you MUST start the engine level. If you try to start with the engine trimmed, it won't start. Fuel leaks out of the carb when trimmed and therefore doesn't make it into the crankcase (top carb i believe) This may have something to do with your hard starting. Also check for water in your fuel tank - pretty common and will give you the symptoms you describe. Also make sure your spark plugs are fresh.

[Eriktheviking]

I'm no outboard expert but heres a couple ideas.Did you Do a compression test? Sometimes when they're tired ,(low compression) they only like to start with starting fluid. You got fresh fuel? Those engines don't like old gas.The primer bulb working? Good luck

[jkeiper]

http://www.checkmate-boats.com/infopop/emoticons/icon_confused.gifNot sure what engine you have. Merc. didn't make a 3cyl. 115. If it is a 1985 it should be a 6cyl. Post a ser.# and we can figure out what it is.

Regards,

Jim

[jkeiper]

http://checkmate-boats.com/6/ws/,s,8626072361/Graemlins/brickwall.gif oops. Chris E. already said what I did.

Jim

[Enforcer 24]

I am no expert on OB's but you said the carbs were rebuilt. Has anyone "tuned" them in? Two strokes are funny when it comes to the mixture screws for the low speed, high speed and idle screws. (both for air pressure and velocity going through through them, hence hard starting, bad idle) Not sure how many carbs you have but I would sugest getting it to run and sync the carbs first. A compression test would be good to do also. 100 psi and up per cylinder is good. Also, maybe the fuel pump is getting weak or you could have weak vacuume pulse to the pump, which would mean low compression being as the base makes vacuume for the pump to operate. Do a compression test first though. If possible, do it AFTER the engine is warmed up (normal operating temp.) and throttle wide open. (unhook coil wire also while doing this so ignition doesn't get burned out) Hope maybe this helps a little. I only know 2 strokes from snowmobiling (10 years worth) and not from boating so this is what I would do on my sled and am thinking an OB would be the same. Good luck and hope maybe something helps I posted.

Oneida Lake, NY

[Diane]

Sorry.. typo. It's a 6 cylinder.

Thanks for these ideas so far. If the thunderstorms ever stop, I'll be able to do some diagnosing. The gas is fresh, the squeeze bulb gets hard. I didn't do compression testing...have no specialized tools. The plugs are from last year but I pulled a couple and they looked brand new.

Diane