1999 Force/Merc 75HP 3 Cylinder 2-Stoke Rough Running Issues

[pshelfo]

It is not a pump.

Boat left me stranded this past weekend and after fishing had a really hard time starting and when did - had to rev and rev and when put into gear died out.

I called a bunch of shops to take it in and no one will work on this motor any more. Got a hold of mechanic who took the time ask me my problem and told me he knew what it was. Said carbs on the motor have a type of “secondary jet” which is permanent and you can’t replace or clean. the rebuild kits for these carbs don’t come with any jet replacements so it kind off limes up. He shared he spent months figuring out this same issue and on 3 of similar Force motors he replaced with a type of carb and the motors ran great afterwards. Gave me a part number of 632061 but said might not be able to find.

Does this hold any weight? He seemed to know what he was talking about as the symptoms matched.

 

[The Force power]

I found "part number 632061" in about 20 seconds on fleabay (not sure if that is the correct one)
Can yours not just be cleaned?

 

[Nordin]

Seams odd to me why the carbs not can be cleaned.
OEM there is a WB-135A Walbro carb for top cylinder and WB-139A for middle and bottom cylinder.
You can pull main jet, main nozzle, idle mixture screw and welsh plug from the carbs and the welsh plug is stock at various websites.
Put the carbs in a ultrasonic cleaner and they will be clean.

 

[pshelfo]

Seams odd to me why the carbs not can be cleaned.
OEM there is a WB-135A Walbro carb for top cylinder and WB-139A for middle and bottom cylinder.
You can pull main jet, main nozzle, idle mixture screw and welsh plug from the carbs and the welsh plug is stock at various websites.
Put the carbs in a ultrasonic cleaner and they will be clean.

Seams odd to me why the carbs not can be cleaned.
OEM there is a WB-135A Walbro carb for top cylinder and WB-139A for middle and bottom cylinder.
You can pull main jet, main nozzle, idle mixture screw and welsh plug from the carbs and the welsh plug is stock at various websites.
Put the carbs in a ultrasonic cleaner and they will be clean.

Thanks for the reply! I have already cleaned the carbs twice (including dropping them into an untrasonic cleaner for an hour or so. The only thing I did not do is remove the welch plug a that seemed a little bit complicated and I read stories of them leaking after you try to reinstall. The last carb clean (after dipping in the ultrasonic cleaner) I made sure I hit all the holes and nozzles with with a hose (per cleaner instructions) and then carb cleaner, and then high pressure air. The only thing I could not remove was the main jet as as on these carbs it is fixed in the middle with no removal.

It also seems odd to me that you can't clean the carbs per this mechanic. Not sure what he meant by secondary jet.

 

[racerone]

Maybe it is not a carburetor problem ??

 

[pshelfo]

Have an update as still struggling. Found out that carb needles are sticking even after replacing with rebuild. Bought new OEM needles and started doing seat polishing process with q-tip, drill and aluminum polish (seats are permanent on these carbs). The odd thing is the q tips are coming out fully black even after running 20 cleans. I tried another carb and same thing. looking into the seats there is one side that look like rubber/carbon but the other parts of the circle shiny brass - very hard to see. This is a head scratcher as the videos online don’t have this issue. Either they are terribly dirty or there is some sort of rubber thing in side (which makes no sense). I stopped cleaning as I a worried I am hurting the seat.

 

[ct1762@gmail.com]

Have an update as still struggling. Found out that carb needles are sticking even after replacing with rebuild. Bought new OEM needles and started doing seat polishing process with q-tip, drill and aluminum polish (seats are permanent on these carbs). The odd thing is the q tips are coming out fully black even after running 20 cleans. I tried another carb and same thing. looking into the seats there is one side that look like rubber/carbon but the other parts of the circle shiny brass - very hard to see. This is a head scratcher as the videos online don’t have this issue. Either they are terribly dirty or there is some sort of rubber thing in side (which makes no sense). I stopped cleaning as I a worried I am hurting the seat.

its funny i am doing the exact same force 3 cyl motor - rare bird as its basically a 90hp with different jets. anyway i also noticed the needles have trouble coming off their seats. i jammed a pen brush on my dremel and got the hole super clean. then carb cleaner squirt. seals perfectly just make sure you blow into the fuel inlet nipples with your mouth to be sure they dont leak, and same for tipping carb right side up to make sure needles dont stick! you dont want to feel any resistance/needle must drop on its own. they should've added a needle clip to the float tang to pull it down.

 

[pshelfo]

I agree and wonder why the heck they made a carb with gravity needles!! I finally got the seats nice and polished and clean. The black q-tip issue appeared to be from the aluminum polish / Q-tip combo using the drill. When I used carb cleaner on the Q-tip in drill all came Clean. Tested and motor fired up as normal and have to take to lake and test. got mixed running results on ear muffs as still sputter some, I still wonder if I have air bubbles as when I kept squeezing bulb it ran a lot better. Thinking about changing primer bulb again. Fuel filter always has air bubbles in it and I am not sure if that is normal.

 

[The Force power]

I still wonder if I have air bubbles as when I kept squeezing bulb it ran a lot better. Thinking about changing primer bulb again. Fuel filter always has air bubbles in it and I am not sure if that is normal.

Maybe picking up air along the way?
Has the fuel-pump / diaphragm been inspected/replaced?

 

[pshelfo]

I think I found the riddle. I cleaned the seats with carb cleaner after the polish and they came out nice and shiny. Something with the Q-tip plus polish plus drill was turning the cotton black. Put new OEM needles in, cleaned and put all back together. Also got a new Sirius primer bulb and fuel filter (ditch the generic primer bulb I got). Also notice I had an oversized fuel hose going from fuel filter to fuel pump and got that nice and tight. Boat starts up much better and does not stall out or die on acceleration. Still fuzzy and I think is burning tool much fuel - motor does not have a high pitch sound at WOT so I think I have to mess with air/fuel screws next.