74 15hp johnson throttle adjustment & water pump.

[someone11]

My first question is, is there a way to adjust the throttle on this motor? There is about an inch or two of play in the twist before the motor starts to rev up. (ill try to word this so its not too confusing)... When the throttle is on the slowest it can go (turn the throttle to slowest speed) I can see that the cam for the throttle control is about an inch maybe almost two inches away from the roller cam. So when you are at full throttle its actually only at half throttle. Is there a way to adjust this?

Secondly, how hard is it to change the water pump in these?

This motor has been sitting for about 10 years and I just got it back up and running today. Just needed a carb cleaning and she started right up.

Thanks in advance for any help.

-Nick

 

[someone11]

Re: 74 15hp johnson throttle adjustment & water pump.

Over 100 views and no replies? Hmm. Well after reading some of the similar threads below (since advanced search turned up nothing) it sounds like it might be the timing plate out of whack? Does this sound right?

 

[OptsyEagle]

Re: 74 15hp johnson throttle adjustment & water pump.

The carburetor needs to be synchronized with the timing plate. On the throttle cam that eventually touches the cam follower (little rubber roller that controls the carb throttle) as you rotate the tiller arm, there should be an arrow indented into the metal. When the cam follower just touches the cam, that arrow should be in the middle of that roller. If it is then everything is sinc'd up. If not, you will see two small nuts that hold that throttle cam to the timing plate. Loosen those, adjust the cam correctly, and then tighten them up.

As for the pump. Yes, it is not difficult and made a lot easier with Leeroy's instructions.

http://www.leeroysramblings.com/Lower_unit.htm

 

[someone11]

Re: 74 15hp johnson throttle adjustment & water pump.

Im not sure where the arrow is that you are talking about but the plate that I think you are talking about is as far forward as it can go. I got some pictures to help explain whats going on.

Here, the motor would be at idle, (handle twisted as slow as it will go)

Here would be like wide open throttle.

 

[OptsyEagle]

Re: 74 15hp johnson throttle adjustment & water pump.

It looks like your throttle cam does need to be adjusted forward. On the picture below is my 1976 15Hp motor. Where the arrow is you can see an indent in the shape of an arrow on the cam. To sinq it up, one wants to ensure that when the roller touches the cam, that arrow is in the middle of the roller. If not, the two nuts just above the cam, to the left in your second picture, are loosened and the cam can be mover closer or further away. Tighen up the nuts and your carb would now be in sinq with your timing plate.

 

[someone11]

Re: 74 15hp johnson throttle adjustment & water pump.

It looks like your throttle cam does need to be adjusted forward. On the picture below is my 1976 15Hp motor. Where the arrow is you can see an indent in the shape of an arrow on the cam. To sinq it up, one wants to ensure that when the roller touches the cam, that arrow is in the middle of the roller. If not, the two nuts just above the cam, to the left in your second picture, are loosened and the cam can be mover closer or further away. Tighen up the nuts and your carb would now be in sinq with your timing plate.

Are the two nuts shown in your picture? And im assuming the flywheel needs to be pulled for this to be synched?

 

[OptsyEagle]

Re: 74 15hp johnson throttle adjustment & water pump.

Yes. The two nuts just above the throttle cam. When the flywheel is off it is easier to access them but I have ground down a 5/16" wrench well enough to get in there without removing the flywheel. Most, off the shelf 5/16" wrenches, will not fit.

 

[jmendoza]

Re: 74 15hp johnson throttle adjustment & water pump.

Check to see that the gears on the throttle shafts where they couple together (at the tiller folding hinge) have not jumped a tooth. This is common.

 

[someone11]

Re: 74 15hp johnson throttle adjustment & water pump.

Check to see that the gears on the throttle shafts where they couple together (at the tiller folding hinge) have not jumped a tooth. This is common.

Is there an easy way to tell if it has jumped a tooth?