2008 Mercury 4 stroke 115 outboard issues

[Sid1955]

I have this 2008 Mercury 4 stroke EFI outboard sit for over a year, I did the tune up it ran great but would die after 10 minutes. Found out that I had to pump the bulb to keep motor running. Found out that the fuel pump had issues and i replaced both high and low volume pump since I was in there. After I put it back together the motor would not start. Starter went out which is hopefully unrelated but rebuilt the starter and then the motor started running really ruff. Got mechanic to visit and we trouble shot it down to cylinder 3 & 4 having no response when we pulled the wires off while running. switched coils which made no difference. changed spark plugs and sent in injectors per mechanics suggestions. injectors were clogged and in poor shape but re-calibrated and cleaned. I put the injectors back on not knowing which injector went where with no difference in the performance of the motor and the same cylinders 3 & 4 are not firing correctly. I know this because I pull the plug wires when running there is no change in performance. if I pull 1 or 2 cylinders the motor dies. Compression test shows all cylinders are at or over 200 and each cylinder seems to be getting spark. Any ideas out there?, because me and the mechanic are stumped. Any ideas would be appreciated!!

Serial# 1B452823
Model# 115F23HD
Family: 6M9XM01.73GE

[lpugh]

Please Read the sticky's at the top of the page and provide all info

[EuropeanAM]

Also a good idea to post this in the 4-stroke Forum (a couple more down the list), and provide the engine serial number. Thanks!

[Sid1955]

Thanks for the info guys. I will be back home Sunday and re-post with serial numbers. Much appreciated.