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Mariner 40hp 3k revs

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dejv

New member
I have a mariner 40hp 2stroke 3 cylinder year 2004-2006, it worked fine for about half a km then it started slowing down till max revs reached 3k. When revving the engine using the idler it is reaching full revs

When boat is on trailer it revved 6k geared.

- I have checked the fuel filter inside the fuel tank
- checked pipe from tank to outboard
- dismantled fuel pump and cleaned everything with brake cleaner nothing seemed torn and needed replacement (although I am not that technical)
- carbs were clean ( I didn't remove the jets just inserted a wire inside all holes I could find + sprayed compressed air inside)
- fuel filter seems fine
- removing the plugs one by one caused the outboard to work not correctly so spark plugs should be ok.
- I have also changed a pipe from carb1 to carb2 to transparent to check if there is air but there isn't

Any other on the check list before I get the boat inside the water again

https://youtu.be/dIkC1P_j0f8

https://youtu.be/9VSWjxaw9Ls










 
The RPMs you can get on a trailer will not equate what you can get under load. Also, to avoid damage to your motor, many advise not going above 3k rpm when the motor isn't under a load (ie. in the water with forward gear engaged).

- Does it always run and reach its usual top end initially when you're on the water and then drops down to 3k rpm as soon as its warm?
- Are the idle RPMs different from when you first launch the boat (cold) and once it gets into its "limp mode" stage (warm)?
- Can you have someone check the primer bulb when you're running at full throttle, but stuck at 3k rpm, to see if it has pressure?
- When you're in limp mode, but leave the throttle wide open, does it feel like the motor is surging up or down at all?
 
[email protected] said:
The RPMs you can get on a trailer will not equate what you can get under load. Also, to avoid damage to your motor, many advise not going above 3k rpm when the motor isn't under a load (ie. in the water with forward gear engaged).

- Does it always run and reach its usual top end initially when you're on the water and then drops down to 3k rpm as soon as its warm?
- Are the idle RPMs different from when you first launch the boat (cold) and once it gets into its "limp mode" stage (warm)?
- Can you have someone check the primer bulb when you're running at full throttle, but stuck at 3k rpm, to see if it has pressure?
- When you're in limp mode, but leave the throttle wide open, does it feel like the motor is surging up or down at all?
Click to expand...

ok noted

1- hard to say as normally when I start the engine I am in the no wake zone, tomorrow I will get the boat down again and t ry it out.
2- idle rpm remains the same
3- will try squeezing the primer bulb while engine in limp mode and report back
4-no don't think so

Tomorrow will get the boat into the water again and record a video as it explains much better.
 
Re: Mariner 40hp 3k revs 2 stroke 3 cylinder

Today I tried the boat.

Drove 1km no wake zone, then drove 7km cruising about 3500rpm before the issue started again.

The below is driving in the no wake zone (working ok till now)
https://www.youtube.com/watch?v=DIt2dLn8Elo

Giving full throttle (around 5k revs for few sec)
https://www.youtube.com/watch?v=LTCgN8jPNFk


Issue happened again
https://www.youtube.com/watch?v=0wnROEG1CDM
https://www.youtube.com/watch?v=FWUBS4d20ks
https://www.youtube.com/watch?v=N5sMmkbonkI

The below video is showing loosing some revs when having the issue and the motor on free
https://www.youtube.com/watch?v=tPouOwuEt-0

When the issue happened I checked the primer pump while driving full speed at 3k revs and it was hard, pumped it just in case but didn't have any effect on the motor still drove with same revs.

I replaced the plugs and while doing so noticed that the one on the top was more wet with fuel than the others (the others were brownish showing a correct burning), went for a quick 3 min drive (motor working ok with new plugs) then gave it some throttle to 4k revs and switched the engine off (with the engine still with throttle).

I checked plugs however they still as new and needed a longer run in order to change the color. However the engine idling was f...... it was idling 1.5-2k revs (could it be since I switched it off with the throttle at 4k revs???)

I reduced the idle screw on the top carb as the others were set at 1.5 turns and this was set at 1.75 turns. But the idling of the motor is still playing.

After getting up the boat I removed the fuel line in order for the motor to empty all fuel inside the system.
 
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