Won't rev when in barrel and engine cover is on (Older 6 hp Johnsons )

[outdoorfan]

I have three older 6 hp Johnsons. I went through the carbs and ignitions, etc, and have been testing them in the barrel. However, I noticed that they won't run worth a darn (starved for air, apparently) when the covers are on. All three of them do the same thing. Pull the covers off, and they rev nicely.

I assume this is normal. Perhaps they run fine with the covers on when the boat is moving through the water and generating wind. I don't know.

Any thoughts?

 

[Daviet]

Re: Won't rev when in barrel and engine cover is on (Older 6 hp Johnsons )

By the way you describe it, you have an exhaust leak, most likely a powerhead base gasket. With the cover off and the engine running, squirt a little oil into the carb and see if you see smoke coming out between the block and exhaust housing.

 

[tx1961whaler]

Re: Won't rev when in barrel and engine cover is on (Older 6 hp Johnsons )

I have three older 6 hp Johnsons. I went through the carbs and ignitions, etc, and have been testing them in the barrel. However, I noticed that they won't run worth a darn (starved for air, apparently) when the covers are on. All three of them do the same thing. Pull the covers off, and they rev nicely.

I assume this is normal. Perhaps they run fine with the covers on when the boat is moving through the water and generating wind. I don't know.

Any thoughts?

Three of them doing the same thing? They are sucking up their own exhaust. They do not like that.

 

[outdoorfan]

Re: Won't rev when in barrel and engine cover is on (Older 6 hp Johnsons )

Three of them doing the same thing? They are sucking up their own exhaust. They do not like that.

Ok, that makes sense. I will experiment by putting the prop-side on the outside of the 55 gallon drum into a 5-gallon bucket. That way the exhaust should have ample area to escape vs sucking up what's pooling inside the big drum.

Thanks.

 

[F_R]

Re: Won't rev when in barrel and engine cover is on (Older 6 hp Johnsons )

Stick your head down by the top of that barrel and you will quickly see why the motors wont run there. They are breathing smoke. Get them out of that barrel and on a boat where they were designed to run.

Anyway, you should not be revving them in a barrel in the first place. It proves nothing and may cause severe damage or destruction. Thinking of revving it in a 5 gallon bucket?? Heaven Forbid!!!! NO!!

 

[tx1961whaler]

Re: Won't rev when in barrel and engine cover is on (Older 6 hp Johnsons )

They probably won't even pump water in a 5 gallon bucket.

 

[kfa4303]

Re: Won't rev when in barrel and engine cover is on (Older 6 hp Johnsons )

+1. Lots of folks get a small electric fan, or a buddy to blow away the exhaust smoke while barrel testing. Don't worry, they won't smoke nearly as much on the open water.

 

[twocyclemania]

Re: Won't rev when in barrel and engine cover is on (Older 6 hp Johnsons )

Not to be funny but try running them (in the barrel) on a windy day. I've experienced the same phenomenon with all of my motors. Every time I go to sell one I have to explain to the buyer whats going on. It's a pain because the motors do sound better (quieter) with the cowling on but run poorly.