115 mercury fires on two cylinders at wot

T

TR17

Recruit
Joined
May 4, 2009
Messages
1
I have a 1998 115 mercury that will not go to wot on all cylinders but idles fine. I can put it in reverse and rev up the engine and then go back in gear and it will run up the lake and is fine. but problem is when you back off and then throttle it back up it does the same thing, I know this engine fires on only two cylinders until the rpms come up and it acts like they are not firing. I have cleaned the carbs and run a external fuel tank and hose to see if that was the problem but with no luck.
 
V

verado7

Chief Petty Officer
Joined
Apr 28, 2009
Messages
511
Re: 115 mercury fires on two cylinders at wot

check your stator with an dvom set to ohms you can get the specs from a manual - could be an issue on the high side of the stator ,also do the same for trigger lastly the switch box .
 
The_Kid

The_Kid

Chief Petty Officer
Joined
Apr 18, 2008
Messages
447
Re: 115 mercury fires on two cylinders at wot

To help determine if the problem is fuel or electrical while it's bogging down try pushing the key in to open the fuel primer. If you pickup RPM you have a fuel problem. It could be the accelerator pump for cylinders 3&4 isn't working or is out of adjustment. There is also a small filter between the accelerator pump and the carbs.

My 95 Mariner 115 was doing the same thing last year and it turned out that the high speed jets were partially blocked. I could bump the key a couple of times and get up to full RPM. I pulled the carbs and gave them a good cleaning and a rebuild and my problem went away.
 
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