Force 120hp won't start

Maus01

Seaman
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Aug 15, 2023
Messages
65
Hello. Iam from the netherlands. I really hope someone can help me
I bought a bayliner with a 120hp force in it.
120ld91d sr nr
Compression on al 4 cilinders is 120psi.
Ignition seema to Be ok. Spark on al 4 plugs. It won't start. Rebuild the fuelpomp
It looks like there is no fuel comming out of the carbs. The primer gets hard. Also when i spray fuel in the back of the carbs... No luck. It putters en hicks. Flames out of the exhaust. Timing is set at 30 degrees wot. I bought the boat with a non running engine. So dont know what happend with it in al those years
Hope sombody can help
 

topgun3690

Lieutenant Junior Grade
Joined
May 7, 2019
Messages
1,034
You didn't mention the carbs.....did you clean/rebuild them, check the floats, etc.....install a clear inline filter between fuel pump and carbs to see if fuel is flowing or not. How long has this engine been "non running" ?
 

racerone

Supreme Mariner
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Dec 28, 2013
Messages
37,722
Pushing the key ( sluetel ) in and holding it in while cranking it over to start ?----Check the flywheel key too.
 

Maus01

Seaman
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Aug 15, 2023
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I took the carbs apart and ultrasonic clean them. The floots look okay. No leaks or so. No New parts, I Can't find a kit on the internet. Dont know how long it dit not run. I rebuild the intire engine. Every gasket, bearing is New.
 

Maus01

Seaman
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Aug 15, 2023
Messages
65
Pushing the key ( sluetel ) in and holding it in while cranking it over to start ?----Check the flywheel key too.
Tried that. The engine stands in my workshop. Shocking help a little bit. If i put my hand over the top carb(inlet) gas i floating out en the engine wil begin to sputter. When i do that at the bottum carb nothing happens
 

Maus01

Seaman
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Aug 15, 2023
Messages
65
Tried that. The engine stands in my workshop. Shocking help a little bit. If i put my hand over the top carb(inlet) gas i floating out en the engine wil begin to sputter. When i do that at the bottum carb nothing happens
Wat do you mean with flywheel key? (sorry netherlands 😉)
 

Nordin

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Jun 12, 2010
Messages
2,553
Have you checked the compression by your self or it is information from pre owner?
Have you checked the timing by your self ?
How have you stated you have spark at all three cylinders?
Do as topgun3690 and racerone says.
Clean the carbs and put a clear inline filter between the fuel pump and the carbs.
Check the flywheel key as back fire is one indication of a shared flywheel key.
The flywheel keys purpose is to set the flywheel to a fixed point to the crank shaft and it is for ignition/timing purpose.
You can check the flywheel key in two ways.
1. Set the throttle in lowest position (idle). Set the top piston in TDC (top dead center) by using a screw driver or a another bar to locate it. The zero mark on the flywheel should line up with zero mark at the timing plate.
2. Pull the flywheel and check the flywheel key.
 

Maus01

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Yes i have checked it all myself.compression spark etc. #carmechanic.. But dont know much about 2 stroke boatengine. The key as you called it is ok. Timing is correct. Tdc nr1 cilinder =zero at the flywheel. 28/30 degrees at WOT. It seems an fuel issue. Does annybody know where to buy a repair kit to service the carbs. Can't find any. FK10288 tomorrow i Will mount clear fuel lines. Maybe things get clearer than
 

The Force power

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Feb 3, 2019
Messages
2,330
Yes I have checked it all myself. compression spark etc. #carmechanic.. But don't know much about 2 stroke boat engine. The key as you called it is ok. Timing is correct. Tdc nr1 cilinder =zero at the flywheel. 28/30 degrees at WOT. It seems an fuel issue. Does annybody know where to buy a repair kit to service the carbs. Can't find any. FK10288 tomorrow i Will mount clear fuel lines. Maybe things get clearer than
You may not need a complete carb repair-kit, just a few parts out of it. MOST parts are available http://www.crowleymarine.com/mercury-outboard/parts/1544_7.cfm
ALSO..............You may want to follow the advice below;
Here's the old post (from the late Frank) that I have printed out & live by;

1.Disconnect the ball link to the carb cam at the timing tower. Disconnecting at the cam risks bending the cam. Move the cam away from the carb roller.
2. Loosen the screw(s) on the aluminum tie bar and let all carbs close completely, then tighten again.
3. Set the cam so that the scribed line is pointing directly at the black roller on the carb lever. If the cam has two closely spaced lines, set the black roller directly between them.
4. The black roller is held with an offset screw and nut. Loosen the nut and turn the screw until the black roller JUST touches the cam. Tighten the nut and re-attach the ball link maintaining the scribed line at the roller.
5. Adjust the ball link so that at full throttle the bottom carb butterfly opens substantially horizontally. Adjust the aluminum tie bar so all carb butterflies open equally at full throttle. They need not be perfect but should be rather close to horizontal for best performance.
6. Adjust timing to 28 degrees before top dead center at full throttle. ( STATIC TIMING / CRANKING SPEED )
7. Adjust idle speed to 700-750 RPM in the water in forward gear. Do this with the screw on the bottom of the timing tower. Loosen the locknut and adjust. Screwing in increases idle speed. Do this in small increments and let the engine rev and adjust itself before the next adjustment. A little goes a long way here. When correct, tighten the nut. Note that the scribed line on the roller will now be (usually) below the black roller a bit.
8. NOW we 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.
8A. 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.
8B. Now go the opposite direction. Adjust until the engine runs rough, burbles, or stalls. Note this setting.
8C. 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.
8D. Readjust idle speed to 700-750 RPM.
9. 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.

10. 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.
 
Last edited:

The Force power

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Messages
2,330
Tried that. The engine stands in my workshop. Shocking help a little bit. If i put my hand over the top carb(inlet) gas i floating out en the engine wil begin to sputter. When i do that at the bottum carb nothing happens
Are the choke-plates closing when the solenoid is energized/ ignition-key pressed in?
 
Last edited:

Maus01

Seaman
Joined
Aug 15, 2023
Messages
65
You may not need a complete carb repair-kit, just a few parts out of it. MOST parts are available http://www.crowleymarine.com/mercury-outboard/parts/1544_7.cfm
ALSO..............You may want to follow the advice below;
Here's the old post (from the late Frank) that I have printed out & live by;

1.Disconnect the ball link to the carb cam at the timing tower. Disconnecting at the cam risks bending the cam. Move the cam away from the carb roller.
2. Loosen the screw(s) on the aluminum tie bar and let all carbs close completely, then tighten again.
3. Set the cam so that the scribed line is pointing directly at the black roller on the carb lever. If the cam has two closely spaced lines, set the black roller directly between them.
4. The black roller is held with an offset screw and nut. Loosen the nut and turn the screw until the black roller JUST touches the cam. Tighten the nut and re-attach the ball link maintaining the scribed line at the roller.
5. Adjust the ball link so that at full throttle the bottom carb butterfly opens substantially horizontally. Adjust the aluminum tie bar so all carb butterflies open equally at full throttle. They need not be perfect but should be rather close to horizontal for best performance.
6. Adjust timing to 28 degrees before top dead center at full throttle. ( STATIC TIMING / CRANKING SPEED )
7. Adjust idle speed to 700-750 RPM in the water in forward gear. Do this with the screw on the bottom of the timing tower. Loosen the locknut and adjust. Screwing in increases idle speed. Do this in small increments and let the engine rev and adjust itself before the next adjustment. A little goes a long way here. When correct, tighten the nut. Note that the scribed line on the roller will now be (usually) below the black roller a bit.
8. NOW we 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.
8A. 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.
8B. Now go the opposite direction. Adjust until the engine runs rough, burbles, or stalls. Note this setting.
8C. 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.
8D. Readjust idle speed to 700-750 RPM.
9. 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.

10. 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.
Thanks i also followed this great explanation ftom frank.... But no luck
Could it be something with the RECIRCULATION system?? Or has this nothing to do from staring the engine..
 

The Force power

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Feb 3, 2019
Messages
2,330
Could it be something with the RECIRCULATION system?? Or has this nothing to do from staring the engine..
Nothing with the start-up of the engine
Nordin asked you regarding the spark that you have not answered?!?
Did you check with a spark-gap tester? or just looking for a spark?
 

Maus01

Seaman
Joined
Aug 15, 2023
Messages
65
Nothing with the start-up of the engine
Nordin asked you regarding the spark that you have not answered?!?
Did you check with a spark-gap tester? or just looking for a spark?
No Just visual. Spark on all 4 cilinders. Not with a tester i ordered one yesterday. How do they (tester) work??
 

Maus01

Seaman
Joined
Aug 15, 2023
Messages
65
By back you mean the throat (front) ?
Has the float been set-up properly on the lower one?
Where they suck up the air.. The another thing.. The top carb is sucking a lot more air than the bottem one.. It is Just a feeling that iam having. But the compression is the same in al 4 cilinders. Reedvalves are looking ok
 
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