6hp sluggish with hood on.....

[Blacktail130]

Hello all. I have a mid 1970's 6hp Johnson that run's great and is reliably responsive to throttle, when the hood is off. The second I put the hood back on it get's "sluggish" to throttle response, doesn't seem to get up to expected rpm's and run's rough. I drilled a 3/8" hole in the hood right in front of the carb air intake but, this changed nothing. All the other air intake area's are free of restriction's. There are no other hole's in the hood except the one I drilled. Any idea's? Thank you, Patrick.

 

[ezeke]

Re: 6hp sluggish with hood on.....

You have to find the source of the exhaust that is leaking back into the engine compartment and block it.

 

[kenmyfam]

Re: 6hp sluggish with hood on.....

Are you getting enough air in there for proper combustion. Check the air inlets in the hood.
Could you be pushing HT wires together when you put the hood on and shorting out somewhere.
Just a couple of thoughts. Start without hood in the dark and look for sparks from the plug wires.

 

[jay_merrill]

Re: 6hp sluggish with hood on.....

Sounds like exhaust problems to me too. Here are the potential causes ...

Exhaust cover screws leaking
Cover plate gasket damaged
Exhaust relief obstructed
Adapter gaskets leaking
Cracked exhaust housing
Exhaust housing to adapter screws loose or missing

 

[tashasdaddy]

Re: 6hp sluggish with hood on.....

the don't like breathing there own exhaust.

 

[ezeke]

Re: 6hp sluggish with hood on.....

Just curious, but are you only running the motor in a barrel when you have the problem with the cover on?

 

[samo_ott]

Re: 6hp sluggish with hood on.....

Exhaust leak under the cowling.

 

[HighTrim]

Re: 6hp sluggish with hood on.....

Just curious, but are you only running the motor in a barrel when you have the problem with the cover on?

Exactly what I thought as I read it, they cant be run in a barrel with the cowl on, if that is in fact what he is doing.

 

[Blacktail130]

Re: 6hp sluggish with hood on.....

Thanks for the replies. Yes I was running the motor in a drum. I ran it today in the lake on the boat and it did seem to run better than in the drum but was not quiet as responsive as I had hoped. As cold as it was this morning (23F) I didn't play around with it much. Also the fact that I had the cowl on maybe it was just quieter and I felt that it wasn't as responsive as I thought it should be. Anyway, thanks again for the replies and when it warms up a bit I'll have your guys advise to look to as I mess around with it. Patrick.