2008 115 hp mercury 4 stroke EFI bogging.

[Kansas115]

I have an issue seems my 2008 115fhp mercury 4 stroke EFI motor takes time to get to full rpms, the rpms drop off after a while then they perk back up. Sometimes it runs rough at idle and sometimes it doesn't. It doesn't miss or backfire but there is an issue. The oil had some fuel in it also. I changed the oil and filter, changed both fuel filters and put some treatment in the gas. Still has the issue. Anyone have any ideas on what my problem or problems may be?

 

[alldodge]

What is the motor serial number
Check your fuel pressure

 

[Kansas115]

My motor number is 1B693754. I rented a fuel pressure gage from Orileys and the fitting didn't fit the top fitting. I disassembled the fuel module this evening looking for cracked hose or something out of the ordinary (I don't really know what I'm looking for other than cracked hose or dirty screen). Still the same issue. Thank you for the response. Could it be injectors? I believe the issue is in the fuel module but who knows.

 

[alldodge]

Been looking at the parts break down for the motor and I'm unable to find the fuel test port. Normally its a Schrader valve which is under a cap, but seems its not there.
https://www.mercruiserparts.com/75-efi-4-stroke-1b366823-thru-2b0949

The service manual is 8M0085380 and would list how to test
I doubt its the injectors, most likely its fuel supply to the injectors. Could be one of the fuel pumps is weak, fuel pressure regulator or a fuel line restriction

 

[joeboater7]

make sure you have good spark on all spark plugs. if not, coils, powerpack, etc might need. A bad coil and bad power pack and me and othe techs try all kinds of fuel and carb diags with no fix. Always check spark in issues with bogging, rough running, etc.

 

[Kansas115]

I will put a regulator, internal hose, and float today and see if it helps. Thank you all very much for the advice! This has been frustrating but interesting, I have learned a lot.