3Hp evinrude 3706c runs with choke on

[hdman97]

Picked up a 67 3hp evinrude.
Can get it run run somewhat with the choke on.
Went thru the carb,and it looks like it was rebuilt not long ago.
Found nothing wrong,coils points cond. look to be brand new.
No history with it as it was from an estate.
Anyone know what the compression should be on this little guy?
Leaning towards that as not much else left.
Thanks

 

[Daviet]

Re: 3Hp evinrude 3706c runs with choke on

I would think the compression should be at least 65-75 and be within 10% of each other.
If you can make it run by pulling the choke on, I would think you have a carb problem. When you went through the carb did you remove the core plug on top of the carb and clean the passages in there, they are part of the low speed circut.

 

[hdman97]

Re: 3Hp evinrude 3706c runs with choke on

Wow that was quick.
I thought it would be the carb also.If you are refering to the welch plug? No I didnt pull that out.
This carb is very clean as it appears it might even be new.
Only getting about 40-45 in both cyls.

 

[Daviet]

Re: 3Hp evinrude 3706c runs with choke on

If you can keep it running by squirting fuel into the carb, you have a fuel delivery problem. Do you have a good flow at the fuel line going to the carb? The low speed passages are tiny under the core plug and are easy to plug up.
The compression is not great, but if it will run with the choke on it is enough to keep it running. It might come up after you get it running and the rings lubed up, or can do a decarb on it.

 

[hdman97]

Re: 3Hp evinrude 3706c runs with choke on

I agree with fuel problem but dont seem to find anything. The flow seems ok no fuel pump on this one just gravity feed.
By decarb do you mean to run some seafoam once its running?
Will try squirting fuel in carb tomorrow.
Think maybe the rings are hung up?

 

[hdman97]

Re: 3Hp evinrude 3706c runs with choke on

Ran engine with seafoam,it smoked for awhile.
Running much better now problem may be solved.
Thanks Daviet