1990 Force 120 2 stroke loss of power high rpm

[Popeye_1990]

Greetings
I have recently benefited from advise given to me here. All has worked out well. Need to solve final issue with force.
Starts great...runs great til about 3500 to 4500 rpms. Motor starts surging. Acts like starving for fuel. I back off throttle almost to neutral and cleans up. I can squeeze the bulb when it starts acting up and It stops. I stop squeezing....surge returns.
Fuel pump? Carb adjustment? Bad fuel? Satan? Any ideas or input would be appreciated. Thanks in advance.

 

[Redbarron%%]

Replace/check the fuel pump diaphragm and fuel filter. Also make sure that the line from the tank and to the carbs has not separated (the internal sleeving) and is not blocking the fuel flow.
Also try to post your question before Jerry gets up early in the morning so that your question gets in front of him (!)

 

[The Force power]

As Redbarron already mentioned;
-start with the fuel pump
-replace the fuel-lines (if you have not done this)
-check the float settings
ALSO;
-check the vent on the tank

 

[Popeye_1990]

Gonna start with fresh fuel in portable tank to eliminate bad fuel...air getting in...check valve. If still does it...could carb be issue?

 

[The Force power]

We both gave you a few things to check..........but fresh fuel is never a bad idea
However if you prime the bulb and it seems to help, how's bad fuel going to be the culprit??????

 

[Popeye_1990]

We both gave you a few things to check..........but fresh fuel is never a bad idea
However if you prime the bulb and it seems to help, how's bad fuel going to be the culprit??????

Bought boat recently. Been sitting who knows how long with 25 gallons of fuel. Thought may be water. Grasping a straws.

 

[Popeye_1990]

We both gave you a few things to check..........but fresh fuel is never a bad idea
However if you prime the bulb and it seems to help, how's bad fuel going to be the culprit??????

Ok. Fuel...fuel line ....air getting sucked in all eliminated. Still drops power at around 4000. Feeling fuel pump. Not sure about carbs tho if worth atteopting anything. Haha...if I did I would k ow what I was doing. If fuel pump....new 9ne not available for this motor. Can I install low pressure electric fuel pump inline and just leave OWN fuel pump as is?

 

[Popeye_1990]

We both gave you a few things to check..........but fresh fuel is never a bad idea
However if you prime the bulb and it seems to help, how's bad fuel going to be the culprit??????

Haha...redbaron. I'll try on the early post. Missed that first read...

 

[Popeye_1990]

Ok. Fuel...fuel line ....air getting sucked in all eliminated. Still drops power at around 4000. Feeling fuel pump. Not sure about carbs tho if worth atteopting anything. Haha...if I did I would k ow what I was doing. If fuel pump....new 9ne not available for this motor. Can I install low pressure electric fuel pump inline and just leave OWN fuel pump as is?

pic of carbs. Not a clue what I'm looking at.

 

[racerone]

Could be some dirt floating around in the bowls.-----Could be dirt in a float valve.---=---Simple carburetors and ultra easy to work on.------If you own an older Force motor you simply have to learn these simple procedures or pay the man $100/ hr !

 

[The Force power]

If fuel pump....new 9ne not available for this motor. Can I install low pressure electric fuel pump inline

You don't need a actual fuel-pump but the inner-guts and that is still readily available.
take a pick of the pump and I'll look for the kit#
DO NOT install an electric pump as you could be building a bomb !!

 

[The Force power]

View attachment 350755pic of carbs. Not a clue what I'm looking at.

You could try first; removing the bowls and see if any debris is in the bowls.
second would be to remove all carburetors and clean the ports & see if the floats are set up properly if they're not? they either flood the engine OR starve the engine at high speed (because it is not letting enough fuel in the bowls fast enough for the demand

THIS SHOULD BE IN YOUR MANUAL

 

[Popeye_1990]

You could try first; removing the bowls and see if any debris is in the bowls.
second would be to remove all carburetors and clean the ports & see if the floats are set up properly if they're not? they either flood the engine OR starve the engine at high speed (because it is not letting enough fuel in the bowls fast enough for the demand

THIS SHOULD BE IN YOUR MANUAL

You don't need a actual fuel-pump but the inner-guts and that is still readily available.
take a pick of the pump and I'll look for the kit#
DO NOT install an electric pump as you could be building a b

You could try first; removing the bowls and see if any debris is in the bowls.
second would be to remove all carburetors and clean the ports & see if the floats are set up properly if they're not? they either flood the engine OR starve the engine at high speed (because it is not letting enough fuel in the bowls fast enough for the demand

THIS SHOULD BE IN YOUR MANUAL

Gonna pull bowls off next.

 

[The Force power]

HERE'S a parts manual

 

[Popeye_1990]

HERE'S a parts manual

Thank you very much!!!!

 

[Popeye_1990]

Gonna pull bowls off next.

Wow. Got some questions now...forgive the length of post.
Checked bowls. Extremely clean. Was surprising
Reassembled and took out. Ran fine on slow acceleration to 4000 rpms. Started to stammer. I wondered what would happen if I pushed throttle pass stammering. Boat surged then sputtered out. Would not restart. Thought would be stranded.
Pulled cowling started adjusting carb til it barely ran shaking. Pulled covers off front of both carb and wiped inside front of carb with my finger.
Grayish fluid built up in front.
Question 1 : what could this be?
Coming in I trimmed motor up and It started running smoother.
Question 2: Could position of engine be related to my issue?

 

[Popeye_1990]

Wow. Got some questions now...forgive the length of post.
Checked bowls. Extremely clean. Was surprising
Reassembled and took out. Ran fine on show acceleration to 4000 rpms. Started to stammer. I worried what would happen if I pushed throttle pass stammering. Boat surged then sputtered out. Would not restart. Thought would stranded.
Pulled cowling started adjusting carb til it barely ran shaking. Pulled covers off both carb and wiped inside front of carb with finger. Finally got back.
View attachment 350800 Grayish fluid built up in front.
Question 1 : what could this be?
Coming in I trimmed motor up and It started running smoother.
Question 2: Could position of engine be related to my issue?

Question 3: When I got in the intake manifold where top carb is mounted was covered with condensation and intake was cold to the touch. Is this normal?
I did find a leak where the fuel line connects to fuel pump. Pulled off..cut line and was about to put back on when I saw this.
Can't see well here but may be a crack or could be that way from manufacturing process.

 

[Popeye_1990]

Question 3: When I got in the intake manifold where top carb is mounted was covered with condensation and intake was cold to the touch. Is this normal?
I did find a leak where the fuel line connects to fuel pump. Pulled off..cut line and was about to put back on when I saw this.View attachment 350801
Can't see well here but may be a crack or could be that way from manufacturing

Next I adjusted on carbs for a while and finally got her running at idle smoothly. I touched nothing else. Normally when coming on power the throttle / shifter control is about half way pushed forward. After all adjustments...boat comes on power with the throttle / shifter control over 3/4 pushed forward. Transition from idling to power was smoother. Will know more tomorrow. Again sorry for long post.

 

[The Force power]

Wow. Got some questions now...forgive the length of post.
Checked bowls. Extremely clean. Was surprising
Reassembled and took out. Ran fine on slow acceleration to 4000 rpms. Started to stammer. I wondered what would happen if I pushed throttle pass stammering. Boat surged then sputtered out. Would not restart. Thought would be stranded.
Pulled cowling started adjusting carb til it barely ran shaking. Pulled covers off front of both carb and wiped inside front of carb with my finger.
View attachment 350800 Grayish fluid built up in front.
Question 1 : what could this be?
Coming in I trimmed motor up and It started running smoother.
Question 2: Could position of engine be related to my issue?

I'm not sure what you are adjusting on the carbs but
Adjust the mixture on the carbs. Set all low speed needles to about 1 1/4 turns out from lightly seated. Do not force as this will damage either the needles or the seats.
With the engine idling in neutral, turn each the needles in equally about 1/8 turn at a time. Give the engine a couple of seconds between each adjustment to stabilize. Adjust until the engine either "sags" or stalls. Note this setting.
Now go the opposite direction. Adjust until the engine runs rough, burbles, or stalls. Note this setting.
Set all needles to the average between the two settings: That is, for example, if it stalled at 3/4 turn out and burbled at 1 1/4 out then set all needles to 1 turn out.
Readjust idle speed to 700-750 RPM.
Take the boat out on the water and do a "hole shot"--Full throttle acceleration from a stop. If the engine "sags" then recovers and picks-up it is too lean. Open the needles about 1/16 turn at a time until the engine accelerates with no hesitation.
If the engine sputters or coughs or burbles, then clears itself and accelerates, it is too rich. Close the needles about 1/16 turn at a time until the engine accelerates smoothly.
I can NOT stress this enough! NEVER set the low speed needles less that 1 turns out no matter how poor the idle or acceleration. To do so will run the engine too lean and detonation and melted pistons at or near full throttle operation will result.

 

[The Force power]

Wow. Got some questions now...forgive the length of post.
Checked bowls. Extremely clean. Was surprising
Reassembled and took out. Ran fine on slow acceleration to 4000 rpms. Started to stammer. I wondered what would happen if I pushed throttle pass stammering. Boat surged then sputtered out. Would not restart. Thought would be stranded.
Pulled cowling started adjusting carb til it barely ran shaking. Pulled covers off front of both carb and wiped inside front of carb with my finger.
View attachment 350800 Grayish fluid built up in front.

Coming in I trimmed motor up and It started running smoother.
Question 2: Could position of engine be related to my issue?

Yes, because it affects the fuel-level in the bowls/float position