engine loses power @ 3K rpm

[Scott H]

1993 200HP TXRR
my mechanic has tried new plugs, cleaned carbs, and swaped out coils, computer, flywheel, and wiring harness with another engine. Then he disassembled the carbs and replaced 3 check valves. Still has the same symptoms. Starts fine, idles okay. Bogs down and misses when tach reaches 3K. Any ideas?

 

[Ray Neudecker]

Re: engine loses power @ 3K rpm

Find a real mechanic instead of a parts swapper would be a good starting place. I would start with replacing the fuel pumps.
Do any alarms go off or the engine just runs out of power?

 

[Scott H]

Re: engine loses power @ 3K rpm

No alarms. Basically @ 3000 rpm and above the motor loses power, starts to miss and appears to starve for fuel or some electrical problem, maybe loss of spark...

 

[JUSTINTIME]

Re: engine loses power @ 3K rpm

tell him to check fuel like ray said

 

[Scott H]

Re: engine loses power @ 3K rpm

Thank you. I'll let you guys know.

 

[Scott H]

Re: engine loses power @ 3K rpm

My mechanic said he checked the fuel pumps and replaced the diaprams and gaskets in them.

 

[Scott H]

Re: engine loses power @ 3K rpm

Two mechanics agree that the electrical system and carbs are good. Next theory is a seal inside the block. Something to do with fuel getting to the cylinders.

 

[Ray Neudecker]

Re: engine loses power @ 3K rpm

It is quite simple to do a leakdown test. The motor will not idle with leaking sealing rings. It is not hard to test for fire. It can be hard to find a fuel restriction.
The symptoms all lead to a fuel restiction if the tests were done on compression and fire.
My experience with rebuilding those fuel pumps has not been good. It is much more satisfactory to replace them. A vaccum pressure test on the carbs would help in the trouble shooting prodess.

 

[yamamarinetech40]

Re: engine loses power @ 3K rpm

I would also vacuum check the fuel supply line starting at inlet to engine fuel filter. If over 2 or 3 inches @ idle, work your way towards tank until you find restriction. If your mechs didn't already do this, find someone else...