1979 55hp Johnson - Fixed Jets?

[jasondainter]

Hi All.

Have a bogging down issue seen here in this video fixed temporarily by covering the lower carb with hand/rag. Problem is fuel related and mix is running clearly therefore running lean.

1979 Johnson 55HP.

After much deliberating and some help in some forums I realised that it seems my carbs (this is the one, there's 2 on mine) do not have adjustable jets of any kind.

Ive been looking for a mixture screw (eg this type you screw out 1 1/2 from all the way in) but I am assuming my model does not have these at all.

I've cleaned out the high speed jet recently (which was quite dirty inside the orifice but didnt fix issue sadly) taking out the orifice entirely but was a bit reluctant to do that on the idle / intermediate jets due to being worried they have adjustable settings.

It seems they dont so my next step is to take both carbs off (again) clean out and reassembling.

Could dirty idle/intermediate jets also cause this issue?

Is there any way to bypass the fuel tank connectors and pump itself so I can rule out any air leaks along the way (without the pump is it possible to connect a manual bulb and pump that way or will that be unreliable?). I'd like to rule that out also.

Any help appreciated. I'm determined to get this fixed in the coming weeks, its been like this for 2 years!....

 

[Faztbullet]

Pull the carbs as there is debris in lower one. Either high speed is obstructed, float upside down, float level misadjusted or trash restricting needle /seat inlet . Only use new gasket kits.

 

[jasondainter]

Thanks Faztbullet appreciate it.

Ive done this 2 times now (cleaned out carbs) but I must have missed something.

High speed jets i did last week and the bottom jet WAS dirty... cleaned out the orifice thinking this was surely it but same issue on boat. bowl on bottom one was fairly clean.

I've just taken both carbs off again and will go through and fully clean both again this time pulling all the jets out (3 on each). Mine are apparently fixed and not adjustable so i'll go ahead and screw back in without having to worry about any 1 1/2 inch out type adjustment Ive read about.

Im pretty sure floats were the right way round but ill align them and check again. My understanding is the float should be raised very very slightly above level, but Ive read conflicting info that they should be totally horizontal with the bowl so I'll go for horizontal this type and if anyone knows for sure please shout. I dont have the float adjustment tool sadly (and they cost a small fortune delivered to sweden where I live).

I'll take / post some pics as I go.

 

[jasondainter]

Ive now taken out all jets. They were pretty clean. Bowls were clean. But noticed a few things already.

The central washer/gasket part 316332 was totally missing on the upper carb. I must have forgotton to add when I rebuilt them before. I had one from my rebuild kit so will add that.

A washer part 317477 (for the idle passage) was missing which Ive added.

Could this have been enough to cause the air leak?

 

[jasondainter]

Correction: washer/gasket part 316332 was missing on the LOWER carb (not top). This looks encouraging. Feels like I might be winning here...

 

[jasondainter]

This was literally missing. (facepalm). Could this be it?....

 

[jasondainter]

Does anyone know how low down the float should drop on these? I saw a video with a guy saying when holding upside down (to drop the float) they should not drop low enough to touch the bottom carb bowl. Is that a good guide? Right now if I try to manually put the carb bown on upside side it looks to me like the float will touch the lower bowl so I assume its good to adjust that also?

 

[jasondainter]

SOLVED! This was indeed the issue. Thanks for the help!