96 Johnson 200hp won’t plane off

[TNmako]

Hey guys, I have a 1977 Mako 21 with a 1996 Johnson 200 hp 2 stroke Ocean Runner. I have been troubleshooting several issues and making progress but last time out, it started, idled, and ran great but it wouldn’t go over 3k rpm and wouldn’t plane off with the throttle lever all the way forward. I could tell she wanted to but just “ran out of lever.” Any thoughts? Thanks!

 

[jimmbo]

You may have a couple of dead cylinders. Could be mechanical, fuel, ignition, or a combination of two or all three.

Start with a compression test.
Spark, can it jump a 3/8" gap? Is the timing advancing correctly?
Fuel system: Fuel Lines, Filters, Primer Bulb, Fuel Pickup, Carbs, Fuel tank venting?
Throttle cable and linkages? Are all the carbs opening equally and fully?

 

[TNmako]

I performed a compression test & all the cylinders have right around 90 psi, which I thought was low but a tech told me that is ok for that particular engine. all the cylinders have spark. I have replaced the fuel line from the tank to the separator, the fuel/water separator, the primer bulb. the carbs are opening equally. I am not sure how to check the timing. I have rebuilt 2 of the carbs, im in the process of doing all 6.

 

[Bosunsmate]

How did you check spark? just seeing they are sparking doesnt mean they will ignite fuel in a cylinder

 

[KG ON]

90psi is fine on that engine. The fact that it starts runs and idles fine is important. You could have a spark advance problem, check that your stator plate is fully advancing, could be an ignition problem or high speed circuit problem in the carbs. Need more info to help you better.

 

[TNmako]

Bosunsmate. I checked the spark with 2 different style spark checker tools.

 

[Bosunsmate]

Have you pumped the fuel bulb while running in case it has a failing fuel pump?
How do the spark plugs look?

 

[jimmbo]

Bosunsmate. I checked the spark with 2 different style spark checker tools.

How large of a gap did the spark jump?