Knot Pursuit

ok, last year my CC 222 with the mariner 3.0 225 (0617953) ecm 825753 2 PI42521202 ran awesome. I wasnt getting full RPM range but no problem with 23" prop at 5300-5400

I put her away for the winter, now she is running lousy No power at all.

List of what I have done.

New fuel lines from tank to motor
pulled carbs, tore down and cleaned (they were not dirty or gelled)
new upper fuel filter
New separator
new plugs (NGK) not champion, will be ordering the champion
Drained tank and replaced with new fuel (fuel tank is from 2011)


cant get over 2000, will not plane at all. sounds ok just no power.

I dropped the my 23" and went to my 21"
Still the performance hasnt really improved a all
wont go above 2500 RPM on load, wont plane up. I had my wife drive, I crawled up into the bow, it will plane in about 30 seconds, but can only get 3900-4000, but still not power like last season.

Where to next?

thanks in advance

Mr Maine

Does it have a mechanical fuel pump off the crankcase? I had an issue with a mariner, was the fuel pump flooding the engine, ran like crap with no power.

Knot Pursuit

I think it does, I will check that out. Thanks for the advice.

Dd24skater

Never buy Champion plugs for a Merc.....NGK only, I'd take a look at the check valves in the fuel pump, make sure your firing on all 6 too

BUP

iTrader: (9)

fuel pressure readings are ?

Fuel samples taken from your gas tank ?

Primer bulb and fuel line is new ? what brand did you buy ? does this new primer bulb go flat while running the engine ? How old and what was the condition of your last fuel line and primer bulb ? the reason I ask is about your old fuel line - Merc internally the fuel lines fall apart causing huge fuel restrictions that still can be your problem. Merc fuel line with the inner core is complete junk - they always fall apart. Also internally the primer bulbs chunk small pieces of rubber as well over time.

Problem with check valve possible stuck - is your exhaust very smokey ?

next info switch boxes and or coils - you need to spark test this motor and watch for all 6 to have a nice solid spark with a professional spark checker..

You really need to check fuel pressure - and run the engine on a portable fuel tank with fresh gas and a new primer bulb fuel line to see if that changes anything

Compression test ???

did you Link and sync the carbs after rebuild / reinstalled properly ???

What carb rebuild kits did you use and where did you buy them ???

before you pulled off your carbs did you mark them in the order they were installed on the intake ? They are installed in that order for a reason and need to go back in that same exact order.

Reed valves in good shape and are not broken and sealing ???

Many questions need to be answered to pin point this problem.

first and foremost I would check for spark then fuel pressure testing and run it on fresh gas and new portable fuel tank with new primer bulb and new fuel line hooked to the engine side taking your gas side out of the mix. This how I would proceed with the basic first then move on to the more indepth stuff.

BUP

iTrader: (9)

Wait a second you say ECM in your post ? Is this a carb app or a fuel injected app ? carb apps have no ECM

Knot Pursuit

Ok, here goes-

Fuel was 2-3 seasons old. when I first launched the boat. it ran lousy, I drained the tank dry and refilled with 58 gals of new gas. Added stabil, ect and replaced separator. Fuel from separator looked ok,

Still ran lousy

Fuel line from tank to separator, looked good. still replaced it because I had tons of it from another project.

Still ran lousy

Checked spark at all 6 plugs with spark tester. I DO have good spart across board.

Inspected ALL 6 coils and harness plugs for damage, none found.

pulled primer and installed new primer (quicksilver 3/8") and new 3/8 fuel line to the motor.

ran only marginally better. Primer does not go flat while running at any RPM, It stays nice and hard.

Replaced pugs with NGKs (same number NGK that came out of the motor)

no improvement.

Pulled all small fuel lines on the motor and inspected. All looked perfect. No cracking no dry rot no degradation.

pulled carbs one at a time, inspected no sediment, not gelled fuel no discoloration. Carbs were installed in original locations. ( no kit numbers at thsi time) I only changed out the gaskets. Needels and jets were clean and perfect. more of an exploritory surgery than rebuild. Was looking for smoking gun

no improvement.

Someone recommended that I check my mechanical advance. This motor does not appear to have mechanical advance, as it is controlled by the ECM From what I have been told, they only made the motors like this for a couple of years prior to going full EFI/ECM systems.

Pics are below.

mrv8outboard

One thing you can try is to use a spray bottle with 50:1 gas in it and spray it into the carbs under a load to see if it is lack of fuel. Did you remove the main jets to make sure they were not plugged?

Knot Pursuit

yeah everything in the carbs looked clean, like brand new actually. even all of the brass parts were still shiny and new looking.

BUP

iTrader: (9)

Floats did you weigh them and or do they sink in a test bowl of fuel ?

Your serial number for the engine is wrong what you posted

IMO it should be

0G17953? and I believe the last number could be a 5 ?

what you posted is completely invalid for any Mariner in post # 1 just saying

you will need this the correct engine serial # to buy the correct parts. I promise I know what I am talking about all about this. Good luck with it