Force not getting over 2500rpms WOT

[trevorrr1]

Hi, I posted on here last summer about my 1988 18ft Bayliner with a 125 force that I cant get to go over 2500rpms, about 12mph roughly. I'm back at working on it again so gonna try to get some ideas, I'm just going to list everything I've done to the motor and maybe you guys will be able to give me an idea as to what else I could check.

-New fuel lines
-Carbs soaked, Bowl Gaskets replaced
-New engine block 138 compression on all cyl roughly
-new cdi boxes
-new ignition coils
-new spark plugs
-new stator
-new battery
-checked for spun prop
-swapped a rectifier off a 50 force didnt change anything
-3 different fuel pumps that I've tried
-Checked all trigger wire sheathings
-Checked screen on Gas tank pickup
-checked throttle cables it opens carbs full throttle

At this point I feel like I've checked or replaced pretty much everything I can think off it being. Since the day I picked the boat up I've had no issues running in driveway on muffs. as soon as its in the water WOT it doesn't go past 2500rpms, cant get on plane.
Previous owner said it happened out of no where one day it was fine, next it lost a ton of power. So thought it would be and easy fix well I was wrong lol

 

[Nordin]

Have you checked for spark at all 4 cylinders?
You said tried 3 different fuel pumps, was the diaphragms new in those or old?
Check for exhaust leaks from gaskets around the adapter plate where the power head is mounted to the leg.
Check the exhaust rubber boot at the back of the leg for leakage.
Are the throttle butterflies open up fully.
How is the timing set at WOT? Should be 28 dgr BTDC at cranking speed.

 

[Redbarron%%]

Check all cylinders with an induction timing light under load. You don't have a trigger coil listed...

 

[jerryjerry05]

Try running with the cover off?

 

[trevorrr1]

Have you checked for spark at all 4 cylinders?
You said tried 3 different fuel pumps, was the diaphragms new in those or old?
Check for exhaust leaks from gaskets around the adapter plate where the power head is mounted to the leg.
Check the exhaust rubber boot at the back of the leg for leakage.
Are the throttle butterflies open up fully.
How is the timing set at WOT? Should be 28 dgr BTDC at cranking speed.

Its getting good spark at idle, not 100% if it is on WOT
No all diaphragms were used, figured one of them would've changed something even if they were all used.
No exhaust leaks at all ran without cowl didnt change anything.
butterflies open up all the way
Did timing last summer also didnt change anything

Maybe the triggers then? that's one of the things I haven't replaced, only checked under the connectors.

 

[Poormansboating]

I had the exact same problem out of my 17' Bayliner with the 50hp. Tried everything mine would only go 11mph no matter what. Changed the prop that didn't even look bad and now I get 25 mph with only me and one other person. My bet is you should change prop. I got mine off eBay Michigan prop was the brand. My 50 is way underpowered so I'm in the process of putting a force 85 on it.

 

[The Force power]

Its getting good spark at idle, not 100% if it is on WOT
No all diaphragms were used, figured one of them would've changed something even if they were all used.
No exhaust leaks at all ran without cowl didnt change anything.
butterflies open up all the way
Did timing last summer also didnt change anything

Maybe the triggers then? that's one of the things I haven't replaced, only checked under the connectors.

Verify if these fuel-pumps are in fact any good? otherwise you're just guessing (my bet would be the fuel-pump)
What are your carb. idle-screws adjustment set at?
Are you checking the spark with a gap-tester?

 

[trevorrr1]

Verify if these fuel-pumps are in fact any good? otherwise you're just guessing (my bet would be the fuel-pump)
What are your carb. idle-screws adjustment set at?
Are you checking the spark with a gap-tester?

well the new block I bought had the fuel pump in it still, I confirmed that it ran fine before buying the block so that ruled the pump out.
carb screws are about a turn and half out, and no I don't have a gap tester. ill have to pick one up

 

[jerryjerry05]

It ran fine before????
Don't assume anything when it comes to any outboard.
Takes 5 min to check the diaphragm.

 

[The Force power]

You said the Carbs. were "soaked" can I assume you cleared all passages with compressed air?
Does it sound like its bogging down?
Check the spark-plugs to see if the burn evenly?
Check for water droplets on the bottom one
Have you set-up the linkage to the carbs. right?

 

[The Force power]

THIS WAS WRTTEN BY THE LATE FRANK A.

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.
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.

 

[puffitu]

My 2 cents; when having the carbs apart and setting floats- how were they set?? I had similar issue; turned out to be the floats; especially the top and it is imperative to follow the link and sync suggested here by force power. What I did is I temporarily replaced the fuel lines( recirc syst) with clear tubing and added see through filter before carbs as well as checked all fuel related connections, this allowed me to closely monitor the way the motor pumps the fuel. Maybe that’ll help ya. Sounds like you’re on the right path so keep calm and it’ll come around. Lots of variables need to be happening at the right moment for these motors to operate; one bad will throw the whole balance off.

 

[trevorrr1]

Once the weather clears up near me I'm going to record some videos of what it does and how it sounds at WOT and see if that will help you guys. I am going to try readjusting the carbs and check the floats though. Thing is I've tried readjusting them so many times but no change at all at WOT. almost seems like whatever the problem is is something I haven't adjusted or replaced yet cause the problem has never gotten better or worse.

 

[Poormansboating]

Try the prop. Worked for me

 

[trevorrr1]

Well after pulling the diaphragm out of the pump it’s torn pretty bad! lol.
Put a new one in, going to take the boat out tomorrow morning see if anything changed. Crazy thing is I still have the old engine block and I checked the diaphragm on that ones pump and it looks okay. But thanks for the fuel pump suggestions hopefully this is the problem! I’ll post an update tomorrow

 

[trevorrr1]

ITS FIXED! she runs amazing lol. thank you guys! Now the only issue I'm having now is when first taking off I have to stand in the front of the boat for it to get on plane and get going. Once its going though it has no problems getting up to 40mph or more if I wanted.

 

[The Force power]

ITS FIXED! she runs amazing lol. thank you guys! Now the only issue I'm having now is when first taking off I have to stand in the front of the boat for it to get on plane and get going. Once its going though it has no problems getting up to 40mph or more if I wanted.

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.

 

[Nordin]

I do not know what pitch is recommended for the prop for a Bayliner 18ft.
Maybe you need to go down one or two step of the pitch.
If you have a 21 in go down to 19 or 17 in.
Each inch will allow the RPM to rise about 200.
As you says it will go 40 mph or more at WOT it sounds you might have a too large pitch to handle a good acceleration with the load you have.

 

[jerryjerry05]

What rpm's at wot?
What prop?
Where's the Trim@Tilt set when accelerating?

 

[The Force power]

I do not know what pitch is recommended for the prop for a Bayliner 18ft.
Maybe you need to go down one or two step of the pitch.
If you have a 21 in go down to 19 or 17 in.
Each inch will allow the RPM to rise about 200.
As you says it will go 40 mph or more at WOT it sounds you might have a too large pitch to handle a good acceleration with the load you have.

My 18' Bayliner Capri (1990) had a 15 P but switched it out to 17 and run full tilt at 5500 rpm when just me in the boat.
With 4 people trim down she runs 5000 rpms