About 1/4 Speed At Full Throttle

[KRC]

Hello, I have I believe an 84 Evinrude 40hp W/VRO. I’m only getting about ¼ throttle at WOT any idea what could cause this?
I have cleaned the carbs (disassemble and blow through with compressed air), checked for spark (both cylinders good spark), checked compression (both cylinders 110) Replaced fuel filter, hose, and tank.
In neutral the motor will rev just fine, put in gear and will not rev nearly as high.
Any and all help appreciated.

[boobie]

How did you check your spark??

[KRC]

How did you check your spark??

Held them close to medal with insulated pliers and turned the engine over.

[KRC]

80’s 40hp Evinrude has no top end speed. Runs very smooth, revs high in nutral but not in gear just has no top end.

[hidef]

Need more details. What type of boat, what size prop? Have you cleaned the carbs, checked spark and checked compression? Finally what is the model number of the engine?

[KRC]

Need more details. What type of boat, what size prop? Have you cleaned the carbs, checked spark and checked compression? Finally what is the model number of the engine?

See my post (About 1/4 Speed at Full Throttle)

[jerryjerry05]

Try rebuilding the fuel pump?
?

[tx1961whaler]

Try this:
With the engine running, pull the plug wire off of one cylinder.
If it dies, that cylinder is good and the other is bad.
If absolutely nothing happens (no drop in RPM) then that cylinder is bad and the other is good.
If it drops in RPM, but stays running then both are good.

It could be as simple as one bad spark plug.

[JB]

Do not start multiple threads on the same problem, KRC. I have merged your two.

[KRC]

Try this:
With the engine running, pull the plug wire off of one cylinder.
If it dies, that cylinder is good and the other is bad.
If absolutely nothing happens (no drop in RPM) then that cylinder is bad and the other is good.
If it drops in RPM, but stays running then both are good.

It could be as simple as one bad spark plug.

I already pulled one plug wire and started the engine, replaced it and pulled the other and the engine still started.

[tx1961whaler]

Ok, you got spark and compression. That leaves fuel.
Make sure all of the linkages are correct and that the carb butterfly opens fully.
If that's OK, then then carb needs to be taken off and thoroughly cleaned (disassembled, soaked, sprayed, blown out) and rebuilt with a kit.
Fuel pump is probably OK if it is not acting like it is running out of gas, and it doesn't sound like you have a spun prop.