No Power Merc

[boat beat]

My son purchased a '69 100horse inline 6 cylinder Merc. supposedly in good cond- it isn't. When testing at home, it idles good and revs good. When on the lake, it has no power. We've gone through the fuel pumps and carbarators to no avail. It has good spark when cranking engine. It has 125 compression on all 6 cyl. Any help would be appreciated. Thanks in advance.<br />boat beat

 

[JB]

Re: No Power Merc

Howdy, Boater. Assumptions: At home you are on flushing ears with no load on the prop and you are using fresh fuel from a clean, vented tank and new hose. If not eliminate the tank and hose as possibles.<br /><br />Get a load on her and start pulling plug wires, one at a time to see which cylinder(s) are not making torque. If it tries to die without a cylinder, that is a good one, If pulling the plug wire makes little difference, that is a bad one.<br /><br />Once you have some weak cylinders identified, Swapping parts can verify that your carbs are working properly and that you really have good spark.<br /><br />If fuel and ignition systems check out and you still have weak or dead cylinders, reeds become prime suspects.<br /><br />Let me know how the above goes and, if needed, we'll plan the next step.<br /><br />Good luck.<br />JB

 

[boat beat]

Re: No Power Merc

at idle we have good fire on two cyl.. the other cyl. are firing but the spark is very weak. is there a test for the trigger on this 68 100 hors that can be done whith a volt ohm meter. i have a manual for 72-85 but i cant seem to use much of that info on this motor.are the trigger leads black, brown, white.the only stator that i know of on this motor is the one for the alt.. thanks for the help

 

[boat beat]

Re: No Power Merc

thank for the ideas. we are now happy boaters again .it turned out to be a fuel leak in the supply line .it was actualy sucking air. it showed up when i was pumping the primmer bulb and fuel was squerting out of line in front of the lower fuel pump thanks