Greetings, Working on an 85 75hp Merc with an idle problem. Basically I can not get it idle and here is what I have done so far....
1. Ck spark and compression--120lbs on each cyl, bad spark on 1&2 changed switchbox to rectify problem.
2. Removed and cleaned both carbs, set idle air mix to 1 1/2
3. Visually inspected reed valves
4. Performed link/sync
5. Replaced fuel pump diaphram and inspected check valves
6. Run engine tuner thru the engine
Basically the only thing I have noticed out of the ordinary is that I can feel a pulse of air out of the top carb when I get it to run as low RPM (1000 to 1500)as I can and of course it will increase as RPMs increase. Bottom carb --no pulse. Looked at the reeds as well as I could, seem ok. I also notice when I spray engine tuner in the top carb it will pick up RPM, usually it is just the opposite. I sprayed a little carb cleaner under the flywheel to see if RPMs would pick up if I had a top crankshaft seal going out but no dice as well. Also another little strangness is the fuel pump does not seem to be working very well. Any help would be GREATLY appreciated. Thanks
1. Ck spark and compression--120lbs on each cyl, bad spark on 1&2 changed switchbox to rectify problem.
2. Removed and cleaned both carbs, set idle air mix to 1 1/2
3. Visually inspected reed valves
4. Performed link/sync
5. Replaced fuel pump diaphram and inspected check valves
6. Run engine tuner thru the engine
Basically the only thing I have noticed out of the ordinary is that I can feel a pulse of air out of the top carb when I get it to run as low RPM (1000 to 1500)as I can and of course it will increase as RPMs increase. Bottom carb --no pulse. Looked at the reeds as well as I could, seem ok. I also notice when I spray engine tuner in the top carb it will pick up RPM, usually it is just the opposite. I sprayed a little carb cleaner under the flywheel to see if RPMs would pick up if I had a top crankshaft seal going out but no dice as well. Also another little strangness is the fuel pump does not seem to be working very well. Any help would be GREATLY appreciated. Thanks