how do you test a carb?

[rstrick624]

I have taken a carb apart and cleaned it on my 1975 mercury 20hp. The motor still won't start, how do i test it?

Thanks
Randy

 

[Vw56German]

Re: how do you test a carb?

There is no real "testing" for a carb. during the cleaning process blow compressed air through every orifice you can and see if you can feel it come out some where in the throat of the carb. (those little holes by and behind the throttle plate. Blow through the fuel inlet and make sure fuel can get to the float bowl. Now that being said can you give us some more details. Have you checked spark and compression? If after trying to start the motor you take out the plugs, are they wet or dry? Have you checked to see if you have fuel to the carb? Could there be a fuel supply line issue?

 

[rstrick624]

Re: how do you test a carb?

The plugs are basically dry. I can pull it a few times an remove a plug, put a match up to it and it poofs. So i think it is getting gas. The recoil pull is is not working well. I have spark on both plugs when i pull and hold them to metal. Also if i put my finger over the spark pull hole, it will suck it in when pulled.

 

[Sunfish12]

Re: how do you test a carb?

Do a compression test. You can spray some fuel in the carb and try and start it. If it starts this will let you know its a carb or fuel supply issue.

 

[rstrick624]

Re: how do you test a carb?

It does not start with gas in the cylinder, yet I have spark. any thoughts?

 

[Sunfish12]

Re: how do you test a carb?

Low compression?

 

[rstrick624]

Re: how do you test a carb?

I am borrowing a compression tester from my uncle tommorrow. I will let you know

Thanks for your help

Randy