200 hp Yamaha is sick.

[P2]

My 1990/91 200etxd is acting up.
I have done a compression test and all cylinders are good. I made a spark tester and all cylinders seem to spark but dont know how good. ( can I measure this?) I replaced the fuel filter/ water seperator and spark plugs this spring.
Problem started with a bit of a " miss " or Shudder on heavy accelleration. ( out of the hole). This engine is now hard to start. Hard to keep idling hot or cold. Can smell fuel at rest. Once up to speed the engine would run ok but noticed rpms and speed are not what they used to be.
Am going to soak the carbs and reinstall. Anyone have suggestions?? Thanks

 

[rodbolt]

Re: 200 hp Yamaha is sick.

double check both fuel pump diaphrams. unbolt them from the block and see if the pulse hole is wet with fuel.
make the tester gap about 1/2 inch

 

[P2]

Re: 200 hp Yamaha is sick.

I'll check that right now, Thanks rodbolt.

 

[P2]

Re: 200 hp Yamaha is sick.

Hey Rodbolt, The pulse hole seems to be dry but will change diaphrams anyways. I believe them still to be original.
A additional note: While under power back to the ramp the motor lost all rpms and very rough. I reduced to idle and then was able to power up again ?

 

[Ray Neudecker]

Re: 200 hp Yamaha is sick.

Replace the fuel pump assemblies. Too many years on the bodies to trust to rebuild. Disasemble the carbs and clean well. Replace the needles and bowl gaskets and reset float levels to spec. Replace the plugs, likely fouled at least one by now.

 

[P2]

Re: 200 hp Yamaha is sick.

Re: fuel pumps.
Does anyone ever switch over to an electric fuel pump rather than the mechanical? If so what kind of output should one have? psi/gph. Have to wait for new original fuel pumps to get brought in. Just curious

 

[Ray Neudecker]

Re: 200 hp Yamaha is sick.

Actually we do it often, most often with hot rod or race motors. Our pump of choice has been with the blue holley and setting the regulator at 6 lbs. Mount it after the water seperating filter.

 

[P2]

Re: 200 hp Yamaha is sick.

Just got back from a great day on the lake. Carbs cleaned and installed. New fuel pumps and plugs. The engine ran well and idled good without stalling. Seems that problem is solved ( thanks guys ) I did still have some hesitation and what i have to call a miss in the engine when pulling a large tube with two teens. This only happens under load and was there before my other troubles. maybe someone has an idea there too??
Thanks again

 

[rodbolt]

Re: 200 hp Yamaha is sick.

with a large tube and 2 teens it may be over propped.

 

[P2]

Re: 200 hp Yamaha is sick.

Just went from a 13.75x21 to a 14 x 19. i will have to pay more attention to see if this occurs alot with out pulling a load.