Got a stumper - 1990 25hp Johnson

[imported_bowfisher]

Brought in for repair of not shutting off when key turned to the off position. Nailed it down to power pack which is common. Power pack on this model is under flywheel.

Replaced pack, motor started right up but acts like its stuck in slow mode. Wont go much above idle and acts like its bouncing off rev limiter.

what I have done:

1) unhooked overheat sensor
2) compression check 125 each
3) cleaned carb thoroughly
4) replaced new power pack with another new on thinking had a bad one outta the box
5) replaced plugs with new - good hot sparky on both cylinders
6) replaced flywheel key thinking maybe it was slightly bent
7) replaced head gasket thinking maybe cylinders were sharing compression
8) worked with electric primer thinking maybe its feeding it too much fuel, pinched off lines with hemo to eliminate that being the issue
9) reeds look good
10) checked fuel pump to make sure it isnt feeding fuel back into crankcase - wasnt

Motor acts like a timing problem to me but dont know how it could be? Excessive smoke, rough running, wont rev up, starts up real easy.

Thoughts from outside the box????

Im stumped.......

THANKS!

 

[Tim Frank]

Re: Got a stumper - 1990 25hp Johnson

So does it shut off now when the key is turned off?

 

[imported_bowfisher]

Re: Got a stumper - 1990 25hp Johnson

So does it shut off now when the key is turned off?

Tim, yes it does.

 

[Tim Frank]

Re: Got a stumper - 1990 25hp Johnson

Starting at the fuel tank, is it fresh fuel?

 

[imported_bowfisher]

Re: Got a stumper - 1990 25hp Johnson

Starting at the fuel tank, is it fresh fuel?

Yes fresh fuel also, I had concernes with the customers fuel so I hooked my tank up to it that I knew is fresh with 91 octane.

 

[Tim Frank]

Re: Got a stumper - 1990 25hp Johnson

Known-good fuel line/primer bulb?
Cleaned fuel pump filter?

 

[nwcove]

Re: Got a stumper - 1990 25hp Johnson

bad ground....faulty connection in the harness?

 

[imported_bowfisher]

Re: Got a stumper - 1990 25hp Johnson

Known-good fuel line/primer bulb?
Cleaned fuel pump filter?

Yes hoses and bulb is good, many outboards ran off the same line last week with no issues.
Have not checked the fuel filter in pump but have plenty of flow to the carb, kinda made me eliminate that one.

Checked ground on harness to find its good. Will double check again though. Could the driver coil be acting up? I have not replaced it yet, also maybe a bad flywheel for some crazy reason?

 

[Tim Frank]

Re: Got a stumper - 1990 25hp Johnson

Float valve sealing correctly?
Adequate intake vacuum?

 

[AlTn]

Re: Got a stumper - 1990 25hp Johnson

if you have it at wot, will spraying fuel mix into the carb throat cause it to die or rev up?..if rev up, you may have to set the float level much higher....experienced something similiar with a '90 9.9 and had to set the free end of the float almost 1/4 " above the the hinged end with the carb inverted. Link and sync as it should be?

 

[glenn property of pam]

Re: Got a stumper - 1990 25hp Johnson

any electrical wires under fly wheel that flex when its advancing timing. possible wire has fatigued and as it moves its breaking contact

 

[AlTn]

Re: Got a stumper - 1990 25hp Johnson

in post #8 you mention the power coil and I asked a tech recently about another UFI problem. He told me that as a matter of routine they replaced the power coil when they replaced that trigger/pp unit on the UFI units as too often it presented problems soon after the trigger/pp replacement.

 

[Cofe]

Re: Got a stumper - 1990 25hp Johnson

Make sure the neutral safety rev limit releases when you put the motor into forward gear. It is a plastic rod that engages the stator plate on the right side of the motor.
When you have the motor off, place the gearshift into forward at WOT. The neutral rev limiter should disenguage and the stator plate should then turn to WOT. The carb butterfly now should be wide open. If it isn't, you should do a link and sync.

 

[Haffiman]

Re: Got a stumper - 1990 25hp Johnson

Throw away the complete UFI system and get either a conversion kit from CDI or an 'old' system from a junk engine.

 

[imported_bowfisher]

Re: Got a stumper - 1990 25hp Johnson

Thanks for the kind replies to all!

I will try replacing the driver coil, I dont normally replace them unless they are not working, and have never had one that work "kind of"
Normally they are good or bad in my expirience, but maybe its a first. Ill also do a continuity check on all of the wires under the flywheel as I did find on with a small nick in it, but put liquid tape on it to seal it back up.

As far as the link and sync, this has been done (forgot to mention that one earlier)

If I had not purchased two UFI I would have tried the the conventional power pack, unless someone wants to swap one out. I have the parts to do the conversion except the on the block pack.

Thanks again