115hp mercury--no power

Betty

Recruit
Joined
Aug 16, 2003
Messages
1
We have a 1971 115hp mercury outboard. It has no power. It starts okay and runs in idle. It revs up in nuetral. But when we take it to the lake, it has no power when you put into gear to "go".
 

ZmOz

Captain
Joined
Aug 13, 2003
Messages
3,949
Re: 115hp mercury--no power

I am having the exact same problem with my '74 150hp. I'm pretty sure it's not getting enough fuel for one reason or another, but I don't know why yet.
 

Gold Bear

Petty Officer 1st Class
Joined
Sep 26, 2001
Messages
224
Re: 115hp mercury--no power

Betty<br /><br />Quite often these engines will stall or hesitate badly when you put it in gear and advance the throttle if the idle mixture screws on the carbs are set to lean. Try this...open each of the carb mixture screws 1/4 to 1/2 turn and see if that helps. These mixture screws should be opened up enough so the engine does not hesitate when trying to get the boat up on a plane.<br /><br />Good Luck,<br /><br />Gold Bear ;)
 

dkwalker

Petty Officer 3rd Class
Joined
Aug 8, 2003
Messages
96
Re: 115hp mercury--no power

I recently purchased a rebuilt 115 and the mech. that sold it to me is wrestling to make it run right... I have gotten some quick insight - maybe I can help.<br /><br />My engine starts and idles fine, but much above 2200-2400 it starts to crap out and just goes doggy. Almost like it's only running on two cylinders.<br /><br />There is the "switch box", a solid state package that mounts on the inboard portion of the engine, about 4" by 5" and 1" thick. 7 wires go to it. No change when they swapped that out.<br />But early on they have been afraid its the stator. This is the stationary coil portion of a magneto and maybe charging system. The stator is located beneath the flywheel. The magnets that are the other half of a magneto system are in the flywheel.<br /><br />I am told the ignition system has kinda/sorta two levels- the low end and the high end. On my engine, the low end goes up to about 2200-2400. Above that, the high end takes over.<br /><br />I can tell you, my engine sounds like it's a fuel problem, but these are the guys that work on and rebuild these motors for a living. I heard the chat between them and they say it acts just like the bad stator problems they have had in the past.<br /><br />Long winded here, but maybe I have helped you out.<br /><br />dw
 

ZmOz

Captain
Joined
Aug 13, 2003
Messages
3,949
Re: 115hp mercury--no power

I got my problem fixed, I rebuilt the fuel pump ($4 diaphram kit) and sprayed about half a can of Seafoam "Deep Creep" into the carbs while it was running. Works great now...does 50mph without any trouble.
 

dstuard

Petty Officer 2nd Class
Joined
Mar 12, 2003
Messages
186
Re: 115hp mercury--no power

I had the same problem with my 1983 115 HP mercury. Turned out to be the stator. Runs like a champ now.
 
Top