FNG here, I have a 40hp Johnson the dies when the cover is closed

[RacingGirlsDad]

I got a boat months ago, for the trailer. The trailer was wrong, so I ended up getting the engine running again to sell it. Well, I had a guy come to look at it tonight, and I was tied of doing to bucket thing, so we took it to the marina, and they put it in the water. They said it ran great, but when the cover was closed it would die, meaning the cover to the carb. This is a 1967 40Hp engine. Where the heck do these things get there air from? I have never messed with a boat engine before, and I need this boat to go, so I can bring my nice boat back home before my buddies dog eats the rest of it. please help, the guy is coming back in the morning, and I would really like to see this go to a new owner. The engine starts right up with the cover open, even after sitting for 6 months, it started in under 2 seconds, with only a half pump on the ball.

 

[bktheking]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

Air intake I believe, it's a silencer plate and pad, located down under the carb in the lower cowl.

Check it to see if it's plugged up, # 11,12,13 make up the parts.

 

[jimdd810]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

You could also have an exhaust leak.

 

[RacingGirlsDad]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

Thank you, I will check that.

 

[F_R]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

Yes, it is an exhaust leak and I'll tell you where it is leaking. It MIGHT be the pleated exhaust relief hose at the rear---where the water sprays out. OR, it MIGHT be the welsh plug is missing, right above that hose.

But if it isn't that, or any other obvious thing, what you have is the o-ring is missing off the top of the water pump housing. AND/OR, if it is a long shaft, there are two more o-rings on the round drive shaft tube, above the extension housing. If any of those parts are missing, it will smother with the hood on and door closed. And it will drive you nuts trying to figure it out if I hadn't told you.

 

[RacingGirlsDad]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

I just got done with another project, so I went back out to look with a flash light. I found oil coming from the top main seal. When I pulled the cover off this time, it smelt like gas. The first thing I checked was the carb, because I just rebuilt it, and it was good. Checked head gasket, and bolts, which are new too, and that was good. It had a blown up coil when I first got it, but I replaced that, and points, condenser, and plugs. This was the first time I have seen oil coming from the top of the block, and all around the seam for the case halves. I looked at the rubber boot that goes out the back, but that looks good, I will check for that plug. Thank you

 

[RacingGirlsDad]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

BKtheKing, thank you for that diagram. My book does not have that, or I have not seen it. I went out and looked, and found no filter at all the, only the top cover was on. This is the first outboard I have ever messed with, and inboard is very easy, at least the new ones, because I just had to rebuild an engine for my daughter's teacher.
I checked the plug above the rubber hose, and it is still in there. It looks like I am going to have to split the case, reseal, and replace the seals. I guess I will do the water pump and thermostat too. I do not like to sell anything that is not running right, and I wish I would have had the trail dimentions before I bought this, and ended up with a pain in the arrsss engine. Thanks again to all. who help.

 

[bktheking]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

Then someone probably yanked it, anyways that's where it draws air from, now to hunt down that leak.

 

[RacingGirlsDad]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

I am sure that the main seal is not helping anything. You can see where it has fresh gas, oil, mix running down both sides of the engine. It was not that way before we put it into the water. I also found the hose clamp lose on that exhaust rubber hose. Before I do anything, I am going to pull the power head off, split the case, reseal, and install a new seal. It also looked like it might be wet under the exhaust cover on the side, but I could not tell for sure.

 

[F_R]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

Well the leaking gas is one problem, but while you are at it you might as well pull thel lower and check those o-rings. It is easier while the powerhead is off. It is a well known and established fact that the o-rings will smother the intake. Well known to techs that used to service them, that is. Other people are still fumbling around in the dark.

EDIT: I might as well tell you the other possible thing while I am at it. There is a thick spongy rubber donut seal between the exhaust housing and outer lower covers. Smoke from a motor idleing in neutral may bubble up through that seal area if it is shot. That problem more or less goes away if you put it in gear and give it a little gas, because the exhaust gets pushed to the rear in the prop wash instead of bubbling up.

 

[RacingGirlsDad]

Re: FNG here, I have a 40hp Johnson the dies when the cover is closed

Thank you