Cannot get Throttle Control properly adjusted on 89 Johnson 70

[sumocomputers]

Recently did a Link & Sync, and I am having a few problems with the throttle control. I will say that the throttle control was never good even before the Link & Sync. I did try to follow the Top Secret post as well as the Factory Service manual. Here are the problems:

1. Once in forward gear, the cam does not move until about 1-2 inches of travel on the shifter, though the cable does start to move right away, but very slowly. In other words the cable starts to move, but the cam lags behind.

I have tried adjusting the cable adjustment wheel at the engine pretty far in both directions, but cannot get it to respond the way I expect, which is that the cam should start to open the carbs when moving the throttle control just after being in forward gear.

I am confident that I have the cam and cam roller properly adjusted according to the factory service manual.

2. When trying to go above 2000 RPM, it is very sensitive.

If you move it just a bit, it sometimes goes a full 500-1000 RPM higher. You almost have to move it slightly and then back to not have it jump so far.

I have adjusted the friction control on the control box to the loosest, but still the same issue.

Am I looking at a stretched cable, or should I look elsewhere like the control box?

Thanks,

Chris

 

[SparkieBoat]

hard to say, those control boxes do have plastic parts inside that can break and make shifting and or throttle cables act sluggish. if it is ever hard to shift you should never try to force it. hard shift is usually a corroded/broken cable. that ends up breaking a plastic part in the box. you could take your box apart and look at it.

 

[sumocomputers]

hard to say, those control boxes do have plastic parts inside that can break and make shifting and or throttle cables act sluggish. if it is ever hard to shift you should never try to force it. hard shift is usually a corroded/broken cable. that ends up breaking a plastic part in the box. you could take your box apart and look at it.

Thanks for the tip.

I will go ahead and open up the control box and take a look, but it is not really hard to shift or accelerate, just not responding correctly out of gear and above 2000 RPM.

 

[SparkieBoat]

the plastic parts can still break. the throttle cable should start moving after the shifter cable has fully engaged. so if that is the hesitation you are talking about it is supposed to do that. If anyone else you know has any hp johnson or evinrude you should be able to look at how their shifter cables work and compare it to yours. they all work basically the same for any size motor.

 

[sumocomputers]

OK, so I know it has been several months, but just wasn't able to get around to digging in deeper until recently.

I went ahead and replaced the throttle cable with a new Seastar Extreme OMC Control Cable, but I still have a dead spot after making sure all the slack was out and the adjustment is relatively tight. Take a look at this video, and you will see what I am talking about:
https://vimeo.com/155242804

My theory is that during that dead spot, the shift cable is still advancing the timing, but the throttle cable is not opening the carbs, therefore the potential stall issue, as well as the jump in speed/RPM if you can get it past the dead spot.

I am pretty sure I am looking at a problem in the control box, but when I had it apart to replace the throttle cable, everything looked pretty good the best I could tell. I did add some grease based on the factory manual and I don't mind replacing some parts inside, but I have no idea where to begin.

Is there a place that rebuilds these older OMC control boxes, or can I purchase a new or rebuilt one that would be a drop-in replacement?

Thanks,

Chris

 

[racerone]

But, but ---The shift cables does not advance the timing.---Your " theory " is wrong on that point !----So find another boater near you to see how control box action compares !

 

[sumocomputers]

But, but ---The shift cables does not advance the timing.---Your " theory " is wrong on that point !----So find another boater near you to see how control box action compares !

OK, fair enough on my amateur theory I just saw the linkage below the flywheel moving with the shift cable, and maybe I incorrectly called that advancing the timing, and maybe not related.

But I still have a pretty big dead spot, and I can see the carb throttle linkages are not moving when I think they should, so it seems like I need to get that fixed, since that is the exact place in the travel that I have issues.

I did find a guy with a very similar Johnson, and it did not have the dead spot like mine. But he wouldn't let me open his control box, and I don't blame him.

It seems like this has to be somewhat common on control boxes this old, and either a rebuild kit or rebuild service should be available, but I just can't find any.

 

[racerone]

Sorry mate.--------There is not that much that can go wrong with the control box to cause your issue.-----But if you have some extra cash you could try a new control box I suppose.

 

[sumocomputers]

Sorry mate.--------There is not that much that can go wrong with the control box to cause your issue.-----But if you have some extra cash you could try a new control box I suppose.

Yeah, trying to find a new control box is something I am Googling right now, but they seem to be like hen's teeth.

Given that your gut says it is not the control box, and I do have a new cable, and I confirmed another Johnson does not have the dead spot, where would you look next?

For the record, I pulled the slack out the best I could at the engine end, but there weren't any specific instructions on how to do that exactly. Maybe still some slack? Any tips here?

 

[Fed]

That 1"-2" of travel sounds like every outboard I've ever owned.

Did you adjust the cables at the motor by the book?

 

[sumocomputers]

That 1"-2" of travel sounds like every outboard I've ever owned.

Did you adjust the cables at the motor by the book?

I did adjust the cable at motor by the book. I re-read the factory service manual, and I think I am going to start all over from the control box back, since I also have a new shift cable I want to install. I will reinspect the control box while I am at it and see if anything jumps out at me. My gut tells me that if the control box itself is OK, then maybe I still have slack even in the new cable.

It only seems logical that the carbs would be opened continuously as the throttle is pushed forward and the cam moves the cam follower, so I am surprised that 1-2" of play is normal, but I have never owned an outboard before.

This is 1989 mechanical technology that I am just not familiar with, so I guess I will just need to keep troubleshooting until I figure it out. As racerone said, it would be nice to have the same exact engine and control that is working properly to see exactly where the problem is.

Chris

 

[flyingscott]

That looks normal to me. The throttle will lag behind the shifting cable because you can't have the motor accelerating while you are shifting it will wreck things. One thing I would do is set the throttle cable so it pulls the throttle assembly tight against the idle screw.Just tighten the thumb screw until it pulls tight

 

[sumocomputers]

That looks normal to me. The throttle will lag behind the shifting cable because you can't have the motor accelerating while you are shifting it will wreck things. One thing I would do is set the throttle cable so it pulls the throttle assembly tight against the idle screw.Just tighten the thumb screw until it pulls tight

I do have it adjusted so the throttle assembly is tight against the idle screw.I think I understand the the small lag you are describing, it makes sense. I am thinking the amount that I have is just too great.

The problem is that if you want to go say 5mph, it is pretty much impossible. You can go maybe 3mph or like 8mph, but not much in-between. It just jumps in RPM and Speed.

Let me just start all over with the service manual and see if I can make any progress. Just wish the control box was transparent so I could see what was going on in there

 

[flyingscott]

It could be your link and sync is there a slight gap between the carb roller and the cam.

 

[sumocomputers]

It could be your link and sync is there a slight gap between the carb roller and the cam.

Yeah, there is .01" gap as called out in the service manual between the cam and cam follower.

 

[flyingscott]

I think your link and sync may be the issue. Did you set the cam and roller with a timing light they need to come to together at a certain point. Then you set the warm in gear idle

 

[racerone]

In your manual what is the " idle timing "--And on your motor do the carburetors begin to open at that point ?

 

[sumocomputers]

So I have done Link and Sync multiple times over the last few months, and don't think that is the problem. I didn't need to set the timing, as it was correct using the Reeve's method at 15 degrees BTDC. Manual calls for 19 degrees BTDC, and Reeve's says it should be 4 degrees less.

So I redid the Link and Sync again, and still there is a very big dead spot of play, even after taking the control box completely apart and inspecting it and reassembling it Nothing seemed worn at all, but it wouldn't take much I suppose.

So before I get a new control box, I took another video that might show more clearly what is happening with the Cam and Cam Roller in conjunction with the dead spot in the throttle control. Tell me your thoughts, as the RPM jump happens exactly at the outer bounds of that dead spot:

https://vimeo.com/158101798

Thanks,

Chris

 

[WernerF]

Looks normal to me. It's exactly what my 1989 60hp did. Link & Sync looks good.

Shift rod hight might be off one turn but is still ok. Lever should be vertival in neutral.

 

[sumocomputers]

Looks normal to me. It's exactly what my 1989 60hp did. Link & Sync looks good.

Shift rod hight might be off one turn but is still ok. Lever should be vertival in neutral.

OK, thanks for the info, I am assuming you saw the dead spot at about 35 seconds in? I think the best way to describe the problem is that when you move the lever, the cam is not really moving, and thus the carbs aren't opening either. Once it starts moving again, the RPMs jump by 500 or so. So if you say yours did the same, I guess the RPM jump is not related to that dead space in the throttle. ​Damn I hate coincidences that turn out to be nothing!

Thing that really bothers me is we didn't used to have this problem, and I can't say for sure if there is any correlation on when the RPM jump issue started happening relative to other work I have done.

The other culprit in my mind has to do with the Ignition System, and neither the stator or timer base are cheap. I only mention those because in some tests I did several months back, the troubleshooting I did with the DVA and service manual indicated one of those might be out of spec. Thinking there might be a dead spot in there somewhere. Sorry if that sounded ignorant, but I am definitely a newbie on engines.

Might just have to live with it...