Power pack problem?

[brian931]

Ok I have a 96 johnston 3cyl 25 hp, J25TKLEDC. The problem is an intermittent one though it happens more often then not. The engine will start up fine and idle great, when I put it gear and give it the gas the engine will 1. bog and likely stall, or 2. bog eventually surge then stall, 3. just continue to bog, or 4. run fine(though rarely). If I do get the engine to run right after it cools down the problem reoccurs. So far I have replaced the tank line, the fuel filter, the spark plug wires, and the spark plugs. I have tested ok for spark on all three cly at idle, I have disconnected the key and kill switch with engine running to rule out a switch problem, and I have confirmed that the floats are full of fuel after a stall. So although it sounds like a fuel problem to me when it dies, is it possible that the ignition circuit is being broken when the motor revs up? Is this the power pack? What exactly does the power pack do? Could this be a carb problem?
Thanks.

 

[samo_ott]

Re: Power pack problem?

Have you tested for spark right after it bogs and dies?

 

[tashasdaddy]

Re: Power pack problem?

that was going to be my question. you have to check when it is giving the problem. you have a coil for each spark plug. could be a coil failing when warm, the only way to find out, is to check spark. if one is not firing, got to the ramp, and completely swap the suspect coil, with one that is sparking. then go back and running the motor till it fails again, now recheck, if the no spark followed the suspect coil, replace the coil. if the no spark stays at the same cylinder then suspect the power pack.

but is could also be, crud getting into the carb. checking the spark is free, and easy to do, first.

report back what you find.

 

[brian931]

Re: Power pack problem?

Ok thanks for the advice, so I tried the boat today ran great, finally got it to start bogging, I could remove the top #1 and bottom #3 spark plug wires with no change so it was only running on #2, I swapped #2 and #1 coil pack and got it to start bogging again and once again it was only running on #2 so coil pack is good, so does this meen power pack???? and do these things fail in this way intermittently??? Putting the clues together it is as if the spark is being turned off at times to one, two, or all three cylinders! Its an expensive part so I want to be as sure as possible!
Thanks

 

[tashasdaddy]

Re: Power pack problem?

yes it is an expensive part, but you have a single carb, so it is not carboration, as it would not single out carbs. look at this 3 cylinder section, try it.
http://www.boatpartstore.com/page32.asp

 

[R.Johnson]

Re: Power pack problem?

A manual point's out how to do a running test on the fuel, and ignition system. Have you checked the main jets' in the carbs, and did you check compression? You need first to know if you are dealing with a sound engine before spending time, and money.

 

[tashasdaddy]

Re: Power pack problem?

very true.

 

[brian931]

Re: Power pack problem?

Well, the fact that I can get it to run like a top with plenty of top end power would lead me to believe that the engine is mechanically sound although I have no compression tester. As for the main jets I have sprayed with cleaner but not dissassembled, but once again the engine has ran great at times I would think a carb issue would not come and go. Do you agree?
Thanks for the help

 

[samo_ott]

Re: Power pack problem?

I would always check compression just to be sure and to have a baseline. Borrow one if you must but they are cheap the testers.

And as for the power pack, I just got one for my '81 J35hp (2 cyl) and the OMC/BRP dealer told me $125 for the OEM part but that they had an after market one for $65 so I bought it and it worked. So that's just an idea for you.

 

[tashasdaddy]

Re: Power pack problem?

before i spent as much money as was listed at brp, i would go thru the carb again. read this. http://forums.iboats.com/showthread.php?t=244013.

this morning i did the dirtiest carbs i have even seen, and the motor was still running. now runs like new.

 

[beansmusic]

Re: Power pack problem?

I just bought the compression test today also for my engine since we are having some problems on our 87 Jonhson. They were only $12 or $13 bucks.