1989 Evinrude 15hp idle issues

[shooter5636]

Hey guys. This is my first post about my first boat. I've been taking care of my dads 2001 Lund Pro V for as long as I've been mechanically inclined, but I just picked up my first boat. 16ft double deep double wide Jon boat that's going to see many a sunrise on duck hunts. My dad gave me a 15hp evinrude for the back. The motor itself only has roughly 20 hours on it, but it hadn't been run since the early 1990's. After checking fluids and getting some fresh gas she started on the second pull. Awesome. Got her out on the lake and I started having some idle issues. 2 things:

1) what exactly does the idle adjustment knob next to the choke for? Obviously it adjusts the idle, but is that more for trolling applications?

2) pardon my lack of technical terminology, but there is a black plastic barrel that rides along a plastic ridge. The ridge gets taller the more the throttle is increased. Problem is that plastic barrel had what looked like a clear rubber/plastic piece on it that disintegrated. I'm wondering if that lack of rubber piece threw the carb out of adjustment enough for it to die at idle sometimes. Is it possible me not having the idle knob in the correct position is causing it to die? It will die at idle regardless of what gear it is in. If you give it gas it revs to life. Absolute no missfires at WOT.

 

[shooter5636]

*edit*

The plastic barrel is called a cam follower. Looked it up on a parts website and used their diagram.

 

[jrs_diesel]

For your first question, that knob next to the choke is your low speed mixture adjustment. On the end of your tiller handle is another knob, this one is the fine adjustment for your idle speed (clockwise will speed up idle). If the idle speed is too low, it can die out at times (mine used to). You only have about 4 revolutions on that knob for idle adjustment.

For your second question, shooter5636 has it correct, that part is the cam follower and is the connection between the timing plate and the carburetor throttle plate. Since yours is broken, you will need a new one. That roller has to be a certain diameter or the throttle will not open all the way. This can also happen if the roller doesn't roll, and a groove can get worn into it, also limiting how far the throttle plate can open.

 

[oldboat1]

For idle issues when running, particularly after a real long layoff, it's probably a carburetor issue (located on front of the engine). The idle mixture screw adjustments are delicate. You might screw it clockwise until lightly seated (closed), then open it counterclockwise about 1 1/2 turns. When the engine starts and warms up, find the best idle operation -- turn clockwise gently (about 1/8 turn at a time, then letting the motor adjust) until the motor wants to stall, then back out counterclockwise about 1/4 turn. That should be close to the right setting. Nice rig. Should be a lot of fun.

 

[shooter5636]

Awesome. I just ordered the cam follower and will mess with the idle once I get the new part. Does the mixture screw stand out in any way? Which side is the easiest to access it from? I haven't really looked at the motor much with the cover off besides to change the plugs and find out where the disintegrated rubber came from.

 

[oldboat1]

The idle screw or needle is the long device protruding from the front of the carb on the front of the end, through the hole in the plastic air silencer in front. It screws into the top of the carb, and will have plastic knob on the end. I would just leave it in place for now, just adjusting it. The carb probably needs cleaning, but if it was stored empty, running the motor might do the cleaning for you. Make sure it's pumping water. There will be water coming out of a hole in the back of the shaft, and out of a little hole on the underside of the pan, under the rear of the powerhead -- but maybe not, as that little hole can be blocked. Operate the motor with the cover off. Watch out for the flywheel, and see if you can hold the heel of your hand on top of the powerhead behind the SPINNING flywheel. If you can keep your hand there for a few seconds before it gets too warm, it's probably close to the right temp. If it smells hot, sizzles when water is sprinkled on the top of the head, it's too hot -- shut it down and start looking for a cause. Two stroke oil in a 50:1 mix.

[The knob has a stop on it. Either pull the knob off, or partially pull it off to adjust the needle (above). if the needle is tightened down, you might need the knob partially reengaged to grip the needle. You will get the hang of it.]

 

[Vic.S]

Details For adjusting the carb slow running needle can be found on the Engine FAQs board at

http://forums.iboats.com/forum/engin...-by-joe-reeves

Pull the knob off. Adjust the needle as described in the above then refit the knob in the nid point of its range of movement.

Useful info on bringing a motor that has not been used for a while back into service also on the FAQs board at

http://forums.iboats.com/forum/engin...rd-by-boatbuoy

As a Newbie its worth looking at the FAQs board index for other useful entries

AND

You will find just about everything else you will ever need to know about your engine in LeeRoy's Ramblings at

http://www.leeroysramblings.com/Outb...0articles.html

 

[jrs_diesel]

If his motor is starting and running, he may not need to adjust the low speed needle at all, and just bump up the idle speed with the idle adjust on the tiller handle. His motor starts up in 2 pulls so that tells me his idle mixture is about where it needs to be. Once he replaces his cam follower he should be all set.

 

[shooter5636]

I'm not messing with the idle until I replace the cam follower. I will report back and let you know how she runs with the part replaced once I get it.

 

[shooter5636]

Replaced the cam follower and idle issue went away. No adjustment needed. Thanks guys.

 

[oldboat1]

Life is good!

 

[jrs_diesel]

Awesome!

 

[oldboat1]

Take a bow, diesel -- nailed it!

 

[jrs_diesel]

Take a bow, diesel -- nailed it!