43 Merc rough idle

"I have a 4.3 that idels very

"I have a 4.3 that idels very rough when cold but once it warms it runs like a champ. I had a recent carb rebuild (last fall) but did not notice this problem at first. It seems to be getting worse with time. Last year it did on occassion now it does it every time it is started when cold. I have changed the plugs but, noticed no difference. I have no ideas where to look. I am afraid to change too much as it runs great after warm up."

"You still have the plug wires

"You still have the plug wires, cap and rotor to check. Rough idle is usually from ignition problems although starving for fuel can cause its own set of issues, too."

"Sounds like your choke pull-o

"Sounds like your choke pull-off is not working correctly. When you 1st start the engine the choke is completely closed. After the engine starts, the choke pull-off pulls open the butterfly so the engine has some air. It is vacuum operated and bolts right on the carb with a vacuum line going to it. If you pull the spark arrestor off before you start your cold engine, you should be able to see if the pull-off is working when you start it up. the rod connecting the pull-off to the butterfly should suck all the way into the pull-off and the butterfly should open at least 1/4 and probably a little more. Good luck."

You might simply have a choke

You might simply have a choke that's set too rich.

Jeff

What is the proper gap setting

What is the proper gap setting for the plugs for a 2001 merc 4.3l

"The gap and other specs shoul

"The gap and other specs should be on the plastic cover on the flame arrestor, along with the correct plug part number (AC MR43LTS, IIRC). Usually, they're set at .035".

What service has been done on this motor since it was new? If you don't know and have only had it a short time, change the plugs, cap, rotor, wires, oil and filter, clean the flame arrestor, do a compression test replace the fuel filter(s) and take a fuel sample."