2011 Mercury 115 4 Stroke - bogging down at mid/high throttle

[freetime72]

I have a 2011 mercury 115 HP four stroke serial number 1B843908

Started with having problems with bogging down at speed. It would troll all day long but sometimes and only sometimes at increased speed it just does not want to go.

Where I have gone so far........
1) Had the old foam style air filter, replaced with newer mesh style
2) Since it was fine at slow speed’s I was thinking it was not getting enough gas and changed both fuel filters
3) Change all spark plugs
4) Drained fuel pump separator to check for sludge...nothing
5) Check fuel lines for collapsing, look good.
6) Its an EFI so I put a new battery in.

Ive run it in between each step to test. Yesterday was the newest test with the battery. Started right up, idled perfect at the dock while I parked the truck. Backed up and sounded great, hit the gas and instantly knew it wasnt right. Backed off and she shut down, wouldnt restart. Back to dock with the trolling motor. Took it home and put muffs on. I can get her started again but doesnt stay running. Seems Im headed backwards, not closer to a solution.

Any ideas?

Thanks,
Dave

 

[rdrast]

Fuel delivery module failure. Extremely common on these motors it seems, and no replacement's are available.

 

[Glenn R Williams]

I haven't been into a 2011 engine, however if your engine is like mine (2007) I would suspect the mechanical fuel pump providing fuel to the high pressure fuel injector pump may need to be rebuilt/replaced.

if your mechanical fuel pump filter is up high on the engine, take the cowl off, and on the lake under acceleration have a buddy watch the fuel filter supplying fuel to the machanical fuel pump. If it goes dry you know your issue. If the level stays the same or just slightly lower, then your injector fuel pump is suspect.

before you change your injector fuel pump, run some high end injector cleaner through your fuel tank and see if that helps. You may have a clogged injector or two. They are easy to clean but require some mechanical ability. If you like I can walk you through that process.

hope this helps somewhat.

Glenn

 

[freetime72]

Getting somewhere positive today.
I decided to go back through everything again. After trying to start a couple of times and hearing the fuel pump kick in I disconnected the first fuel filter just inside the motor. It had no gas. This tells me the fuel pump wasn’t sucking it up or there was a clog. Disconnected the fuel line between the motor and the deck where it leads to the main fuel tank. When I tried to blow through the line I couldn’t. Nothing getting through. Replaced the fuel line and bingo! Fuel pumped sucked up gas and she fired, ran good. No clue how I missed this before.

Back to the launch, started and ran well but not superb. Was able to run all the way to full throttle and did for around 30 minutes up and down the river.
BUT..... I’m not getting the acceleration or top end I’m used to. RPM are a good 800 ish short of what it will normally do and overall speed was 5-7 mph short of normal.

Back home and pulled the plugs. All have a decent amount of carbon build up, 3 tips are white and one totally black.

I’m getting somewhere but not home free yet! I keep looking.
To be continued.....