Re: need help with a mercury outboard

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Posted by Ed Mc. ( on July 25, 2005 at 11:21:00:

In Reply to: need help with a mercury outboard posted by Shawn on July 24, 2005 at 19:14:01:

It could be just a case of too-lean idle adjustment.

Look at each carb and you'll see, at approx. the 1 o'clock position, a slotted screw. This is the idle mixture needle.

Take each one of these and turn it counterclockwise (CCW) about 1/4 turn.

Then try the boat in the water and see if it accelerates better. If the adjustment was a step in the right direction but it still bogs, make another adjustment to each carb but this time only 1/8 turn CCW.

You can also try hitting the 'choke' button momentarily, while you're experiencing your flat spot. If the motor picks up, it's definitely running lean at idle.

BTW you can diagnose a weak fuel pump by pumping on the primer bulb to see if the motor picks up.

If the fuel pump diaphragm(s) were ruptured, it'd spray raw fuel into the motor and it would run excessively rich.

Now, if it's not the carbs you'll have to delve further into the motor, such as proper compression, spark on all cylinders, etc.

You may wish to pick up a repair manual; the Seloc line of outboard manuals is pretty comprehensive and it lays out very well the troubleshooting techniques you'll need to diagnose your motor's problems.

HTH and G'luck........ed

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