Re: Inconsistent Idling 3.0 Merc.
Since I'm a fellow 3.0 owner and this ? comes up almost every other day on the forum. First off educate yourself on your power plant and download your engines manual from the stickies section @ the top of this forum (adults only) there are also various other common issues that can be checked and are listed there as well. but after that be smart and do not start just replacing parts without trouble shooting 1st also test after each change of component or adjustment to pin point issues. With all that being said you could be looking mostly @ a fuel delivery issue but! that involves the most least expensive test 1st check fuel tank pick up tube screen, anti siphon valve,and vent for stoppages or clogs. 2nd remove and check all fuel lines for debree change and or clean all fuel and water seperator filters and test fuel pressure to carb from fuel pump (specs in manual) if all's good from there.3rd ensure you are getting two good squirts into the carb throat when throttle is engauged if not suspect a carb rebuild (most likely cause of your issue). 4th remove check, clean andtest all electrical connetions and components ALL! look for shorts in the dark (a little blue arc) only use OEM replacement electrical components or your wasting money!. But all of this will be a waste of your time if you have not performed a full tune up plugs,wires,cap-n-rotor (points&condensor)oil change and filter as well as a timing check to merc specs along with a compression check on all 4 cylinders. A couple of thing to keep in mind are that these little workhorse engines suffer from occassional block casting crack's under the manifold and blow by between cylinders from blown head gaskets and poor winterization practices. I'm sorry for being so long winded but I tried to remember eveything I did and didn't do when I had these issues and I'm sure I missed something but someone will chim in and point it out.Do a forum serch on your issue and find more info to help but anyway welcome aboard and good luck post back with your results.
