DaveAnd1972
Recruit
- Joined
- May 11, 2011
- Messages
- 5
I Have a 1999 4.3LX motor, I rebuilt the motor Due to #2 Cylinder failure (Cylinder wall scored, wrist pin siezed). So I had blocked bored .30 over and head the Heads done!! I put the engine back together and I barely ran. After trouble shooting just about everything I found the coil bad, Plug Wires bad, Cap and Rotor bad. Replaced all previously mentioned parts! Oh replaced Stock mercruiser Spark Plugs!! Fired up engine and it ran O.K. but really rich and fouled out the plugs!! Checked the carb and found idle adj. screw all the way out!!! Eng. ran before like this!!! WTF!!! Properly adj. carb and engine Idles well. Timing is correct at 10 ATDC My problem is when I wet tested boat The engine ran well up to 2500 RPM's then started missing and backfiring thru the flame arrestor. It would run so bad that it took me 5 min of feathering the throttle to get the boat on plane!!! Where after 3500 RPM's the engine would run better, but still misses and a occasional backfire!! I disconnected the Shift interrupt switch but had no change in performance!!! Checked compression and found 135 across the board!! SO I'm at a cross roads. Who thinks it sounds like a bad ign.module, has anyone else had this problem??? Been reading other posts but nothing like my issue!!! I would really like to know the Ignition Module is bad before spending the money to replace it considering I am $1,550.00 in the whole already on the rebuild. My next wet test I am gonna leave the Distributor loose and manually advance the timing to see if I quits missing and backfiring!!! Any input apperciated!!