1998 150 Johnson 1800 rpm max

[ntarver0568]

1998 Johnson 150 hp (model # J150ELECD) running steady at 1800 rpm max in the water, runs 4.5k + fine when not under a load. This is my father in law's boat and I recently had the same problem with my 1998 mercury 150 hp and it was a bad stator. I just wanted to get some input before I go and waste $250 on the part and that is not the problem.

 

[jonesg]

Re: 1998 150 Johnson 1800 rpm max

The title states 1800 max rpm,
but you state it runs 4500 ok.

4500 is 1000rpm down from 5500.
If thats on a hose, don't do that, it needs the load to keep it from throwing a rod.

I wouldn't be surprised if theres a dead cyl somewhere.

Compression check and spark test are in order first.

 

[nymack66]

Re: 1998 150 Johnson 1800 rpm max

Heres some pointers if this engine is so equipped.. You did mentioned you see 4k not under load...
If the engine overheats, the S.L.O.W.? overheat warning system will automatically limit engine speed to approximately 2,500-RPM. The overheat problem must be corrected and the warning system reset before you can return to normal operation.