1995 150 - Low Power and Bafffled - SOLVED

[Fl_Richard]

I have one of two engines that seems to have about half the power of it's twin.

When I run the good one at WOT (by itself) it goes to about 3500-3800 RPM
When I run the other at WOT (by itself) it goes to about 2500 RPM

Both together at WOT one runs 55-5800 and the other barely reaches 5000. I'm sure the good engine is dragging the other along.

Compression is (1-6) 100-98-100-95-100-88-100 (1000 hours on the engine) with the throttle wide open, all plugs removed cranking fast and the engine had cooled down for two hours after a good run.

I've checked the timing with a timing light it reads 6 degrees at idle and 20 degrees at WOT after the engine has warmed up and SLOW is not active.

I've pumped the bulb while at WOT with no change. Pressing the primer at WOT slows the RPMs.

I've sprayed premix into the carb throats and no change

I pulled the plug wires (new grey ones) while it was idling one by one. All had spark, shocked me and made a slight change in the engine noise.

I re-build all six carbs last year with OMC kits.

I havent decarbed but when looking into the cylinders with a orthoscope i see very few light carbon deposits.

All the plugs are similar and light brown except for #1 which is blacker than the rest.

Where do i go from here? I'm thinking maybe a float is stuck and flooding a cylinder??

Please help! I really dont want to take this to a local dealer. My experience with them has been less than stellar.

Rich

 

[Fl_Richard]

Re: 1995 150 - Low Power and Bafffled

Re: 1995 150 - Low Power and Bafffled

^^^^ BUMP^^^^

Please any comments are appriciated. My thoughs are Power Pack or Carburation?

 

[jonesg]

Re: 1995 150 - Low Power and Bafffled

Re: 1995 150 - Low Power and Bafffled

How are the coils on the slow engine?
I guess the convenient thing with twins is you can swap parts and find out, its a bit of work though.
But swapping powerpacks isn't too hard, you have the factory manual?
And a seafoam treatment wouldn't hurt anything.

 

[jonesg]

Re: 1995 150 - Low Power and Bafffled

Re: 1995 150 - Low Power and Bafffled

Oh yeh, when checking coils its best to remove them and really examine closely, especially the bottom where its potted, look for small cracks.

 

[Fl_Richard]

Re: 1995 150 - Low Power and Bafffled

Re: 1995 150 - Low Power and Bafffled

I havent looked at them. I will tonight and let you know what I find.

THANK YOU! I'll take any suggestions at this point!

 

[tashasdaddy]

Re: 1995 150 - Low Power and Bafffled

Re: 1995 150 - Low Power and Bafffled

take a induction timing light with you, when under way check spark on each cylinder, they could be firing when cool and failing when warm.

also are you sure you have the same prop on each motor, that would make a big difference, different pitches.

 

[Fl_Richard]

Re: 1995 150 - Low Power and Bafffled

Re: 1995 150 - Low Power and Bafffled

PROBLEM SOLVED!!! Finally... I finally put this problem to bed. Now I wont know what to do with my spare time

Yesterday I removed the carb drains and pumped a few bulbs of fuel out of the drains. I though I caught a small piece of debris coming out of one but it was hard to tell for sure. I swapped coils , plug wires and powerpacks from the good motor to the stumbling one and took her out for a spin and OMG the BOTH engines run perfectly!!

There must have been somthing in the carb bowl plugging the high speed jets and my "rinse" flushed it out. Several experts JB-EZ and others have pointed to the carbs telling me to re-built them. I ALWAYS thought it couldnt possibly be them, I just rebuilt them last year and I know I did a perfectly meticulious job of cleaning them. It HAD to be something else. Well I checked everything else bought an ocilliscope to diagnose the powerpacks, checked compression several times, replaced plugs, and even looked into the cylinders with an orthoscope.....

The problem wasnt dirty carbs it was debris in the carbs. Some of you old timers may take exception to this and say debris = dirty carbs. I say I cleaned every passage twice and assembled them perfectly. I KNOW they were squeeky clean and it couldnt possibly be them.

I owe all the experts here my undying gratitude and my humble apologies. If I had taken your advise and looked at the carbs last year I would have saved many hours and some cash too.

You were right! -- I was wrong and stubborn. (My wife would love to read this)

Thank you all!!!

Richard

 

[tashasdaddy]

Re: 1995 150 - Low Power and Bafffled

Re: 1995 150 - Low Power and Bafffled

"The problem wasnt dirty carbs it was debris in the carbs. Some of you old timers may take exception to this and say debris = dirty carbs."

damn dirty carbs, = something it them that does not belong, stopping the flow.

a carb can be clean, and when you put the fuel lines back on you can just chip the rubber, and have dirty carb again.

also alcohol resistant lines are a must now days.

Glad you got it work out, Hard head.