92 johnson 90 hp problem

[John Beckham]

My problem is confusing me. Our 90hp Johnson runs well while out of the water,hose hooked up for water, it'll run all day long. When I put it in the water and put it into gear it'll run for 10-15 min then shuts off and will not restart. If i wait for an hour or so it'll restart and it'll run fine then same problem. I'm by no stretch of the imagination a mechanic. Any help would be appreciated

 

[Mhaskamp]

Sounds like a power pack. When the engine warms up if the power pack is going out it will shut it down. Once the engine cools it’ll start up again. Had a similar issue a long time ago out of the water it was fine but in water once it warmed up it would shut down. Power pack was the issue for me.

 

[John Beckham]

Sounds like a power pack. When the engine warms up if the power pack is going out it will shut it down. Once the engine cools it’ll start up again. Had a similar issue a long time ago out of the water it was fine but in water once it warmed up it would shut down. Power pack was the issue for me.

Thank you!

 

[oldboat1]

Need water pump service -- change the impeller (running on muffs is not a good test). Power pack is a good guess, and subject to damage from overheating. Additionally, there is a water-cooled regulator that can actually flame out if the water level in powerhead drops.

 

[jakedaawg]

You can choose to throw expensive parts at it. One may also choose to diagnose and replace only those necessary.

You may decide it is best to run on 50:1 premix while preforming these tests.

Step one would be to run a compression check just to verify you aren't throwing good money after bad.

Step two would be a waterpump service as preventative maintenance and to insure new parts aren't damaged.

Step 3 would be a spark check done when it is in its failure mode. With the new waterpump functioning correctly run the boat til it fails. At this point do the spark test and other related procedures outlined in the service manual.