I bought a used 90hp johnson that never idled correctly. It runs fine as long as the throttle plates are just cracked open, but as soon as they close the engine dies. I am unable to confirm my throttle pickup timing at 4 degrees BTDC with it running because of this problem. COULD THIS BE THE IDLE CIRCUIT, AND IS THIS DUE TO IDLE JET OR BLEED HOLES?? It runs great above 1500 rpm up to 5000 rpm. I have gone through factory manual and web Q&A's and stumped. Compression on cylinders is 110, 115, 108, 105 (fact. manual says ok if within 15 psi); nice blue spark at 7/16"; rebuilt carbs; rebuilt VRO; plugs are tan, although #3 plug is slightly darker (108 psi compression). All fuel, oil, drain lines appear tight and clean and all fittings are original types. Primer bulb seems ok. I removed powerhead last year and cleaned carbon out of the exhaust jacket area where the powerhead and center tube meet. When I set the ignition timing at cranking speed with plugs removed and grounded, I read that the setting should be 4 degrees before desired timing as the igition system advances the timing by 4 degrees as it runs. either way, mid to WOT is ok, but I can't get the engine to idle with the butterflys closed. The idle speed jets are clear, but the screw slots are slightly messed up from the previous owner's rebuild. IF PROBLEM IS BLEED HOLES, CAN I RUN WIRE OR CLEANER THROUGH THEM WITH CARBS INSTALLED? SHOULD I RUN A DRILL BIT THROUGH IDLE JET SCREWS (.034") OF CORRECT SIZE OR LARGER? I tried putting grease over throttle shaft bushings to determine if too much air into venturi was problem, but sealing with grease did not affect. WHAT SHOULD I EXPECT TO GET FOR A TIMING VALUE AT APPROX. 700 RPM WITH THROTTLE PLATES CLOSED WITH THIS ENGINE? All assistance is greatly appreciated!
