Evinrude 40hp problems

[weedbite]

I have an 86' 40hp Evinrude VRO. It idles a little rough and it bogs if I give it full throttle. It runs good at low-mid range which can get me around the small lakes. It seems to run rich also. It has good spark and compression (140 each). I cleaned both carbs but still have problems. Any input would be greatly appreciated.

 

[Joe Reeves]

Re: Evinrude 40hp problems

WeedBite.... You are describing a engine that has clogged high speed jets. They are located in the center bottom portion of the carburetor float chambers... easily overlooked. If you didn't remove them to clean, or if leaving them in the float chamber, clean them manually (scrape them out with a piece of solid wire), those clogged jets would make the engine act exactly as you've explained the problem.

 

[weedbite]

Re: Evinrude 40hp problems

Thanks Joe. When I cleaned the carbs, I pulled the jets and inspected them. I'll check them again just to be sure and run a wire through them like you suggested.

 

[Joe Reeves]

Re: Evinrude 40hp problems

Weed.... One other thought. Check the timer base under the flywheel. When throttle is applied, it should slide smoothly towards (and eventually hit) the rubber cap on the full spark advance screw stop. If it sticks, the spark would be retarded. This would also cause hesitation, cause the engine to bog out etc.

 

[weedbite]

Re: Evinrude 40hp problems

Well, I checked the jets and they were ok. I did notice that one of the carbs was missing a gasket. It is the small, circular gasket that fits between the bowl and the carb. My thinking is that fuel was getting through which was not metered by the main jet thus causing a very rich condition for that cylinder. Before I ran the boat this year, I had gone through the carbs and I must have misplaced that little gasket. The problem started after I did this. I'm gonna pick a new one up and see if that fixes the problem. I'll check the timer base also to make sure all is well there.<br /><br />One other question. Shouldn't there be an air filter in the intake? It never had one and have always wondered why there wasn't. Seems like there should. My Dad bought the motor used and I don't think it came with one. I know the air is pretty clean out on the lake but bugs can't be good for a motor to digest.

 

[Joe Reeves]

Re: Evinrude 40hp problems

Weed..... Yea, leaving a required gasket out of a carburetor is not a good idea. Wish you had mentioned that previously.

 

[22WRF]

Re: Evinrude 40hp problems

Shouldn't there be an air filter in the intake?

It's not a "air filter" it's a silencer and not required alot of folks take them off and leave them off for easy access to the carbs.

 

[Paul Moir]

Re: Evinrude 40hp problems

I remember reading an artical where after removing the flame arrestor from a (I think) rotax engine's carburator they picked up a lean condition at something like 3700 rpms. It was a narrow rpm range and only showed itself on special knock sensors, but it did explain a reliability problem. Anyway, ever since reading it I've never been keen on removing parts of a stock 2-stroke's intake system.

 

[weedbite]

Re: Evinrude 40hp problems

First, I didn't realize the gasket was missing until after I posted the question. I'm gonna go ahead and replace the gaskests in both carbs and also the needle valves.<br /><br />I think you guys misunderstood me about the air filter question. It has an intake silencer but no foam or paper filter inside. Is the filter on the engine cover somewhere? I've worked on many 2-stroke motors (mostly snowmobiles) but this is the first outboard I've worked on so this is all new to me.

 

[Joe Reeves]

Re: Evinrude 40hp problems

Weed.... THere is no filter. If a filter of any kind existed in that cover, it would be an obstruction, a restriction that would act as a choke, flooding the engine.