MY MOTOR DIES AT IDLE SPEED ?

I have a (1975 ?) MERCURY, 80 HP, IL4, outboard that dies at idle speed when hot and is a pain to start till it cools down like it is flooded. I can do the work ot it myslef if i know what was wrong. we took it in and thay said would cost $3000, but the guy wouldnt tell me what was wrong. any ideas or suggestions are welcome.

Re: MY MOTOR DIES AT IDLE SPEED ?

Howdy, Forjen. $3000.00? He must want to rebuild. Wont say what's wrong, but he wants 3 grand to fix it? Never go back there.<br /><br />Start with compression check and plug inspection. <br /><br />I'm no Mercspert, but would settle for 110-125# with no more than 15# difference. I've been told that those old Mercs originally had in the neighborhood of 150# compression, so don't be surprized if you see that much.<br /><br />Your plugs should be tan, with not much deposit. Black and sooty, bad. Tiny beads of aluminum, worse. Big differences in appearance, not good.<br /><br />Unless you have changed it this season, change your impeller. A failing impeller fails first at low speed, where it is a displacement pump. It may still work at medium and high speed, where it becomes a centrifical pump.<br /><br />Let us know what turns up.<br /><br />Red sky at night. . . <br />JB