Compresson on 150 Johnson

[bottomfishin]

I have readings of 85 psi on all three left side and 95 psi on right.
Isn't this a little low? Would decarbing help? It is a 1989 model.
Thanks

 

[5150abf]

Re: Compresson on 150 Johnson

Is that hot or cold, if cold it should come up a bit, if hot then it is at the top of the low range, 100+ is considered good and you are at the outside of the 10% variance too.

Decarb certianly won't hurt anything but don't expect a miracle either.

When you recheck, all plugs out with a freshly charged battery, It will help the engine spin as fast as possible.

 

[JB]

Re: Compresson on 150 Johnson

After the decarb I suggest you try another (screw in) guage, too.

 

[bottomfishin]

Re: Compresson on 150 Johnson

Thanks to both, I'm new with the outboard mechanics and trying to learn on the fly. Boat runs very well but was concerned that it may need a rebuild soon.

 

[emdsapmgr]

Re: Compresson on 150 Johnson

If it's a basic 150, 95 is normal. If it's a GT/XP, it could be higher by 10 lbs. Be sure you take all the plugs out when doing the compression testing. Ditto on the decarb recommendation.