Motor falls on its face at 1500rpm

[Bryan9633]

Engine: 1989 Johnson GT150

I have an engine that was rebuilt by a local marina last spring. The engine runs great over 2000rpms and idles ok. When I accelerate from idle the motor wants to die right at 1500 rpms weather I hammer down or roll on the throttle. I can push in on the choke a couple of times when it starts to stumble to keep it going and get through the 1500rpm point so im sure its a fuel issue. Here are some facts:

Motor was rebuilt last spring.
90 psi compression on all 6 cyl.
5% leak down, hot
Motor falls on its face at 1500rpm
There are no air leaks in the fuel line.( I ran on separate tank and bypassed the filter, fittings, etc.)
I sprayed carb cleaner around back side of carbs and had no rpm changes
Carbs were re-jetted by two diffrent marinas to help cure the issue with no success.
I have been through the carbs and they are as clean as can be.
Last time I was in them I raised the float hight, it made no difference.

Any ideas? Im at a loss on this one and I belive my local marinas are as well. Would carb jetting create an issue like this?

Thanks!

 

[sutor623]

Re: Motor falls on its face at 1500rpm

Carb jetting needs to be set for your altitude NO EXCEPTIONS!! You are saying that you can get the motor to rev over 1500rpms, just not at 1500? I am confused...