1975 25 HP Johnson Cam Roller Not Meeting Cam

[Acton]

Just bought this motor a month ago in working condition. Did a stupid thing and forgot to strap down back of the boat and drove a few miles with it like that on the highway with the back of the boat bouncing around before I realized what was going on. Mind you it wasn't jumping up and down in the air, but the noise was what tipped me off.

After that motor wont start. Had the motor trimmed up so I know it didn't hit the road or anything. People might read this and think of an extreme situation, but it wasn't anything like that. After that I tried to figure out why my motor wouldn't start and I saw the cam roller wasn't meeting the cam at all, even when I had the throttle handle turned all the way up. First thing I figured was that the gear teeth on the throttle handle had jumped out of alignment, but that doesn't seem to be the case. There's 3 smaller pegs and one larger pegs that match up with where they should be on the opposite gear.

I took a look at schematics of the intake manifold and carb and I think my problem is that I'm missing part number 0318439, "Throttle lever to choke bellcrank link", but I can't be sure.

The only other outboard I've got experience on is a 1978 15 HP evinrude and the link and sync process is completely different on that motor. There's a screw that you can adjust on that motor to move the cam roller left or right so that the cam roller will be between the two marks on the cam just as the butterfly opens. There's nothing like that on this motor. I have no idea on how to adjust the cam roller on this motor. There's no way to adjust the cam either as there's no slot to slide the cam forwards or backwards under the cam like there is on some other motors.

I threw a video up on youtube to show you guys whats going on. I've got an appointment with the mechanic next week anyway as I was planning to have them throw a new carb kit and water pump in, but I'd like to learn more about my motor and see if I could fix this myself. I've learned a lot on here so I figured trying to troubleshoot this might teach me a thing or two even if I cant figure it out msyelf.

https://www.youtube.com/watch?v=kI4Ln9C5428

Second video with a closer look at where the cam follower is in relation to the cam.

https://www.youtube.com/watch?v=IIeoeYCgTAM

Edit: So I took a second look and I'm definitely missing the throttle lever to choke bellcrank link. Without that it seems like the throttle butterfly wont open when I open the choke butterfly with the choke handle. Looking at the diagram of the intake manifold it looks like the "screw fastener #0303686 between the lower and upper throttle lever link is the way to move the cam follower #0384697. The real question here though is how did I lose both the throttle lever to choke bellcrank link AND throw the cam follower completely out of alignment? Is it conceivable that jarring of the motor could cause BOTH of these things to happen? I looked all around the motor and couldn't find the throttle lever to choke bellcrank link. It seems to me like someone would have to get in there with a screw driver to adjust the throttle lever link. Can someone confirm this is how to adjust the cam follower?

 

[gm280]

Acton, I watched the video. But it looks like it is contacting the same area as it always did from the marks on the cam. But not being there and seeing for myself, that is only going by the video.

You state the engine won't run, did you check for spark? And are you certain there is fuel in the carb? So many things we need to know before trying to offer a viable idea.

I would start at the basics and verify spark, fuel and if those are there and nothing, then I would suspect bad fuel or a very weak compression. But we need more info to provide better ideas and suggestions.

Has this engine run before and if so, did it crank easily and seem to have enough power? Have you mixed up some 50:1 fuel mixture and squirted any in the carb to see if it fires? Too many unknowns to make even an uneducated guess at this point. :noidea:

 

[Acton]

I bought the engine 1 month ago. At that time it had 120 PSI on both cylinders. Started up on 3rd pull after it was pulled out of winter storage. Got up to throttle quickly and idled just fine. Saw no issues with it then. I did mix 50:1 fuel/oit mixture with ethanol free gas.

I might need to shoot another video. The cam roller never touches the cam, even when I turn the throttle all the way to the left.

Did another video, here it is. Will also update the original post with the second video

https://www.youtube.com/watch?v=IIeoeYCgTAM

Regarding checking for spark and fuel delivery to the carb those are things admittedly I have not checked. Right away I noticed that the cam roller doesn't touch the cam whatsover until the cam is at wide open throttle so I didn't go on to check those other things yet. I had planned on buying an in line check light before I noticed this. Primer bulb stays stiff on the fuel line as well. Hopefully the second video I posted should show more clearly what I'm talking about. Just to be clear the cam is not meeting the cam follower at all which means the throttle plate never opens even at WOT.

 

[flyingscott]

The adjustment for the link and sync is on the throttle rod itself there is a coupler that can be adjusted. You do not have full throttle because the motor is not in gear. There is a throttle stop to prevent overreving in neutral it will drop out of the way when it is in gear. Check for spark because even with the throttle cam being off it should at least fire. What part do you think you are missing.

 

[Acton]

The adjustment for the link and sync is on the throttle rod itself there is a coupler that can be adjusted. You do not have full throttle because the motor is not in gear. There is a throttle stop to prevent overreving in neutral it will drop out of the way when it is in gear. Check for spark because even with the throttle cam being off it should at least fire. What part do you think you are missing.

The part that I think I'm missing is part number 0318439, "Throttle lever to choke bellcrank link." If the throttle plate is completely closed the motor should still fire? Wouldn't that mean that the motor isn't getting any air whatsoever? From what I understand about the link and sync process the throttle plate should just start to open when the cam roller on is between the two marks on the cam. At this point even at wide open throttle the throttle plate is still completely closed because the cam roller isn't close enough to the cam to ever make physical contact with it. I agree that checking for spark should be the first thing I should do whenever the engine stops working. I plan to buy an inline spark tester later on today.

 

[flyingscott]

Do the link and sync the coupler for the rod is clearly in the video. You loosen the screw and adjust it until the carb starts to open between the 2 marks. When the link and sync is done you will have throttle movement. Even if you are missing the (0318439) link when you turn the throttle up for starts it will do the same thing. That link is to make it easier to start by pulling the throttle open just a little so you don't have to. By you opening the throttle manually it will do the same thing as the link.

 

[Acton]

Looks like the problem was that the cam follower wasn't sync'd properly. After resynced the motor starts now. I'll post a video below. Now the motor doesn't idle and dies as soon as I throttle it down.

Is this because I'm missing the plastic idle adjustment stop screw (0552368) on the throttle control gear (0384864), or does it just need a good carb cleaning? If anyone is wondering the schematics for thee throttle gear can be found under the exhaust housing tab on shop2.evinrude.

I tried to adjust the lean/rich fuel knob but it didn't seem to help much. Like I mentioned in the original post when I first bought the motor I was able to idle it all the way down with no issues. Now as soon as I idle it down to shift on the throttle handle the motor dies.

Here's the video:
https://www.youtube.com/watch?v=dv2ZCSNJk9k

 

[flyingscott]

It sounds like it will idle pretty well once you get the adjustment screw. You can clean the carb put a good rebuild kit in it. Those will shut down if the throttle is turned down far enough. The words on the throttle handle are a suggestion only they are usually not very accurate.

 

[F_R]

Two suggestions:

1. Take the hood off while running it in a barrel. It is inhaling it's own exhaust
2. Sounds like the slow speed needle needs adjusting. Or perhaps you didn't get the link & sync correct.

 

[oldboat1]

^^think maybe that jarring ride could have loosened up the needle (changed the setting). Doesn't take much change to make a difference.

 

[Acton]

Thanks for the tip on the hood, didn't consider that the motor might not have been getting enough air.

On the topic of the slow speed needle, is the rule of thumb to turn it in until it's lightly seated, then take it 1 and 1/2 turns out, where one turn is from 12 o'clock back to 12 o'clock and then a half turn to six o'clock? Or is it something else?

 

[oldboat1]

imo, need another three or four inches of water in that tub, and don't rev. Suggest you let it idle at the lowest current speed, and let it warm up while monitoring temp. (cover off). I'll guess the mix is a tad rich. If you adjust clockwise in slight increments, you should get an increase in rpms -- throttle down at that point (might end up at the slow idle you are looking for with just that adjustment). 1 1/2 from lightly closed is the conventional starting point, but think I would start from where it currently is and see what you get by tweaking it a little.

 

[tblshur]

cam follower roller looks to me like it may be worn out. i cant tell on this screen. may check it . have a good day