1957 7.5 hp johnson project

[sucena]

I've been working on this project, replaced the impeller, and cleaned the carb (bought the car kit for it). While it starts and works on high speed but the moment i select low speed it just dies.

Any ideas?

 

[hockeyfann]

Re: 1957 7.5 hp johnson project

I just started a project on my 1957 10hp sea horse having the same problem!!!!!!!!!

 

[cr9c1]

Re: 1957 7.5 hp johnson project

My guess is something is plugged in the low speed circuit not allowing fuel to get into the engine. Cleaning the carb may not be enough. The low speed circuits on the carbs I've worked with have very tiny holes and I worked on one on a 9.5hp that all 3 small tiny holes were clogged. No low speed at all, it would sputter and die.

Be a good idea to get a carb rebuild kit with new float and core plugs and take the old core plugs out and make sure you really give it a good going over.

 

[Daviet]

Re: 1957 7.5 hp johnson project

Where do you have the low speed needle valve set, 1 1/4 turn out from lightly seated?

 

[sucena]

Re: 1957 7.5 hp johnson project

My guess is something is plugged in the low speed circuit not allowing fuel to get into the engine. Cleaning the carb may not be enough. The low speed circuits on the carbs I've worked with have very tiny holes and I worked on one on a 9.5hp that all 3 small tiny holes were clogged. No low speed at all, it would sputter and die.

Be a good idea to get a carb rebuild kit with new float and core plugs and take the old core plugs out and make sure you really give it a good going over.

I got the car kit and still no good. Could it be points or coils?

 

[sucena]

Re: 1957 7.5 hp johnson project

Where do you have the low speed needle valve set, 1 1/4 turn out from lightly seated?

That's where I started and still no change. Could it be points or coils?

 

[buster01]

Re: 1957 7.5 hp johnson project

Just a thought, I have a 7.5 Sea horse 1958. I was having a similiar problem and found the float was installed upside down...bought a new carb kit and soaked the housing in carb gunk cleaner overnight.

After blowing all the orfices and holes out I installed the kit (float tab pointing toward the main carb body) and presto it started first pull and now idles great.

I am not sure if it was reversing the float or a good cleaning or both but I am glad it worked.

Cheers,
Dave

 

[sucena]

Re: 1957 7.5 hp johnson project

Dave

I'll give it a try. I'll take a look at the carb again.

Thanks

 

[kfa4303]

Re: 1957 7.5 hp johnson project

Here's some tips on setting the hi/lo needles too. have you adjusted your idle set screw at the base of the vertical throttle tower? Is the compression ok? should be over 60 psi or so, and within +/- 10% of each other.

http://forums.iboats.com/showthread.php?t=167352