1979 115 jonhson will starve for air when cover on

Guerra1984

Recruit
Joined
Aug 3, 2010
Messages
2
Here is the thing I dnt knw much about this but I'm sure that I can work on it my motor will run fine with out the cowling cover but once I put it on will star to starve for air if anyone can help me to resolve this problem it will be really appreciated thanks in advance
 

Happy_Jack

Seaman Apprentice
Joined
Aug 13, 2009
Messages
41
Re: 1979 115 jonhson will starve for air when cover on

That is unusual for the V4 motors to starve for air with the cover on.

First, did you check the air inlet areas? may be one in the pan, and one on the back of the cowling where the handhold is.

On my 1987 90hp, it is in the cowl mostly.

Obviously, check for obstructions, displaced sound deadening material covering the holes.

Here is another thing to check on that, sometimes the spark plug wires ground out against the rear cowl latch pieces, if it grounds the two lower cyliders when you drop the cowl on, that might be what you are experienceing. Just a guess, but worth a chaeck to see if your plug wires are routed tight to the heads, and to check if the boots on the 2 lower plug wires are deteriorated, or show signs of arcing?
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
28,370
Re: 1979 115 jonhson will starve for air when cover on

Check for an exhaust leak. Maybe it is starving for oxygen?
 

rlb9844

Petty Officer 3rd Class
Joined
Jan 27, 2010
Messages
82
Re: 1979 115 jonhson will starve for air when cover on

If you have dirt dobbers where you are they may have your air ports clogged. If not then I also would think exhaust leak.
 

Daviet

Fleet Admiral
Joined
Sep 24, 2008
Messages
8,958
Re: 1979 115 jonhson will starve for air when cover on

Blown power head gasket allowing the cowel to fill up with exhaust?
 

wilde1j

Vice Admiral
Joined
Apr 15, 2002
Messages
5,964
Re: 1979 115 jonhson will starve for air when cover on

... or adapter gasket leaking.
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: 1979 115 jonhson will starve for air when cover on

With a motor that large you probably aren't running it in a tank---are you? If you are, there's your answer.
 

Guerra1984

Recruit
Joined
Aug 3, 2010
Messages
2
Re: 1979 115 jonhson will starve for air when cover on

Thanks to all of you guys I'm going to check but most likely there is and exaust leak once I find out I will keep update it thanks again
 

steve6

Seaman
Joined
Aug 14, 2009
Messages
70
Re: 1979 115 jonhson will starve for air when cover on

the one guy mentioned the grounding of the wires, the coils can take a beating by people putting the cover on. pretty common on these i found out this last weekend when i went to get a power pack and two new coils. I had a spark plug cap arching to the tie down, and one of my coils was cracked, i found out the hard way by putting my hand near it while it was running, ZAP
 
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