Boat loving AMT
Recruit
- Joined
- Jun 13, 2017
- Messages
- 3
So I need some help please. I have a 2002 Mercruiser 5.0 MPI S/N-0M331599. A little history; I purchased the boat used from a private seller in 2015. Mercury service bulletin no.2003-06 was my first issue right off the bat. Somehow Wonderland Marine managed the impossible and was able to R/R the ECM under recall. Previous owner tried and failed twice to get it covered. Now I am wondering if the new ECM is the root cause of my lean issue or if Wonderland Marine had one laying around that was corrupted or the wrong one for my engine S/N? The boat ran great up until the fall of last year when I noticed a fluctuation of power above 1300-1500 range that accompanied what seemed to be a misfire, popping or pre-detonation. I figured it was bad gas. It was the end of the season so I drained the tank down as far as I could and used an external tank to winterize after changing the water separator. This spring I decided to move to 100% zero Ethanol fuel 93% octane. I filled up. The problem from last fall was still present. Not only that but after a few minutes of running close to full throttle the engine shut down. Had a hard time keeping it running and after less than 2 min of running I got an alarm and the boat seemed to go into limp mode. I broke down and took it into the dealer where it was discovered Cyl. 5 & 7 were at 0 compression with cracks in the pistons and on Cly #1 at 120 PSI (the lowest still reading) and the piston appearing acid washed. Cyl #8 was 180 PSI. Didn't remove the head to inspect Cyl 2-8 but a borescope showed similar appearances to #1 in Cyl 4 & 6. So I R/R'd the long block and now I am breaking in a new Motor. Long story short, I fixed the problem but still have a cause. The motor is running Lean. I haven't even began to advance past 1800 RPM's in fear of repeating the damage. At R/R I also r/r'd Fuel Injectors, Cap/Rotor, Water pump and impeller. During troubleshooting yesterday, I returned the original Fuel Injectors back to the motor just to eliminate the new ones from the equation. No improvement. Spark plugs indicate a lean engine. Note all sparkplugs removed from the damaged engine looked fine with exception of 5 & 7 which the electrodes were melted. So I need help getting this problem under control before I damage another motor. Please help!! All indications, fluid levels appear good and no alarms have been present. New engine has aprox. 1 hr 40 min. first hour of break-in was performed on land with flush muff. The 40 min was on water on and off 5 different times. Fuel Pressure is 34-38 PSI, I also ran with a remote fresh fuel supply and a new water separator/fuel filter with no improvement.
