1994johnson150fast strike

[catcher1]

When I run motor at full throttle and back off real fast I am getting noises in powerhead,sounds like every thing loose and rattling.Took compression test and all cyl. were 100-110.Also the 3cyl. on right facing from rear are fouling after a few hours use. Can anyone give me any help?

 

[Dhadley]

Re: 1994johnson150fast strike

The noise you hear is called "decell knock". It shows up in some 60 degree motors. What plugs and fuel are you using? What RPM will it turn with an average load?

 

[catcher1]

Re: 1994johnson150fast strike

This is an 18ft Ranger bass boat with a 4 blade 131/4 X 25 prop,Champion plugs#QL78YC,at around 5300-5400rpm trimmed out. Am using 89 octane gas. Is this decell knock harmful?

 

[Dhadley]

Re: 1994johnson150fast strike

It doesn't hurt anything. If you have a manual jack plate, try raising it to get more top RPM. Right plugs. Don't go any higher on octane. It won't hurt to push in the primer as you back off. That should make the noise go away. You can also play with the jets to make the motor richer. Remember the mid range jets meter air so you have to go to smaller numbers to go richer.

 

[catcher1]

Re: 1994johnson150fast strike

Thank you Dhadley.<br /> New question: Is average compression of 100-110 on all cyl. the sign of a strong angine or the sign of a well used engine?<br /> Also any ideas what might be causing all 3 cyl on starboard side to foul out while 3 0n port side are fine?<br /> Thanks again<br /><br />------------------<br />partners1999@yahoo.com

 

[Dhadley]

Re: 1994johnson150fast strike

The compression sounds OK. Are all 3 starboard plugs fouling out or just the top one? What exactly happens? E mail direct if you like -- dhadley50@aol.com.