1983 merc 18hp

[Mercnewbie]

I recently bought a 83 18hp merc, has fresh carb kit new fuel lines new plugs.... it idles nice and at low speeds seems to run fine. Once at wot it begins to sputter and hesitate, im leaning towards possibly a starvation issue? Any suggestions on how to pin point the issue?

 

[flyingscott]

Who rebuilt the carb? Were the correct gaskets used? Base gasket on correctly? What is compression? Do you have spark on both cylinders? Have you tried pumping the primer ball when that happens?

 

[Mercnewbie]

Carb was rebuilt by a local marine tech , i would hope he used the right gaskets nothing looks out of place, i havent had a chance to check the compression yet and both cylinders have good spark and yes and it was firm

 

[flyingscott]

The ball should not stay firm after it has been running. Does that carb have the fuel pump built into it? What is your serial #

 

[Mercnewbie]

7198278. And no it is not built into the carb

 

[flyingscott]

Your fuel pump should be built into the carb on that motor. Check the base gasket of the carb.

 

[Mercnewbie]

Your fuel pump should be built into the carb on that motor. Check the base gasket of the carb.

What exactly would i be looking for?

 

[RickM46]

Look here: http://www.marineengine.com/parts/mercury_marine_parts/sn/07198278/ 1018202/677_7

 

[flyingscott]

The fuel pump on the carb gets the pulse through the carb body from the intake. Sometimes people put the base gasket on wrong and it will cover the pulse hole. You need to make sure that is on correctly and not covering any holes. The ball should go soft after it has been running for a little bit.

 

[flyingscott]

You also want to do a compression and spark test. Also make sure all the linkages are working correctly.