grumpyjoe79
Recruit
- Joined
- Feb 13, 2012
- Messages
- 3
Hello,
I have a 1992 21' Thompson with a 4.3 Mercruiser. I have read a lot of the posts on this forum and I have tried everything suggested and still have the same issue. The engine idles great but as soon as you hit the throttle there is absolutely no power and it takes FOREVER to get the boat on a plane. Once on a plane it run great until you hit between 4200 rpm or WOT then the engine rpm fluctuates. I have tried everything that has been suggested below.
?Fuel condition. Type and Octane possibly old fuel - I RUN 92 OCTANE AND USE FUEL STABILIZER AND ADDITIVES FOR WINTERIZATION I ALSO DRAINED THE FUEL AND ADDED NEW FUEL SO THIS CAN'T BE THE PROBLEM
?Propeller pitch or diameter, damaged blades - BOAT RAN GREAT TWO YEARS PRIOR AND NEVER CHANGED THE PROP NO DAMAGE TO PROP AND I EVEN BOAUGHT A NEW PROP SAME PITCH AND DIAMETER SO THIS CAN'T BE THE PROBLEM
?Restricted fuel pickup tube or anti siphon valve Fuel System Test - RAN A FUEL LINE STRAIGHT FROM FUEL PUMP TO PORTABLE FUEL CAN SO THIS CAN'T BE THE PROBLEM
?Crankcase oil volume, high oil level can cause aerated oil and lifter collapse - CHANGED THE OIL MYSELF AND CHECKED AND RECHECKED OIL LEVEL SO THIS CAN'T BE THE PROBLEM
?Marine growth on hull and outdrive - BOAT ISN'T STORED ON THE WATER AND HAS BEEN WASHED AND WAXED (TO INCLUDE HULL) SEVERAL TIMES SO THIS CAN'T BE THE PROBLEM
?Wrong gear ratio in outdrive - BOAT RAN GREAT TWO YEARS PRIOR AND NEVER CHANGED THE THE OUTDRIVE ALTHOUGH IT HAS BEEN CHECKED AND SERVICED SO THIS CAN'T BE THE PROBLEM
?Restricted carburetor air intake (clogged flame arrestor) - CLEANED FLAME ARRESTOR AND EVEN RAN ENGINE WITHOUT IT SO THIS CAN'T BE THE PROBLEM
?Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive - REMOVED SHUTTERS AND RAN (FOR TESTING PURPOSES ONLY) THEN REPLACED THEM SO THIS CAN'T BE THE PROBLEM
?Poor cylinder compression Compression Test - DID A COMPRESSION TEST ON ALL CYLINDINDERS AND THEY ARE FINE SO THIS CAN'T BE THE PROBLEM
?Carburetor defective, or wrong type. - REPLACED MERC CARB WITH BRAND NEW ROCHESTER CARB SO THIS CAN'T BE THE PROBLEM
?Fuel pump pressure and vacuum - DID A PRESSURE AND VACUUM TEST AND WAS WITHIN SPECS SO THIS CAN'T BE THE PROBLEM
?Boat overloaded, improperly loaded, or improperly trimmed. - HAHA YA OK....I WEIGH 175LBS I THINK I'M GOOD HERE
?Engine Overheating - THIS IS OBVIOUSLY NOT THE PROBLEM
?Engine timing and ignition system operation - I ADJUSTED THE TIMING AND REPLACED PLUGS, WIRES, CAP, ROTOR, DISTRIBUTOR PICK UP, COIL ETC. THEN I WENT THRU THE MANUAL AND DID ALL THE DIAGNOSTIC CHECKS AFTER REPLACING EVERYTHING JUST TO MAKE SURE I DIDN'T BUY ANY FAULTY PARTS SO THIS ISN'T THE PROBLEM
?Remote control cables and linkage for proper travel to open throttle plates fully. - I EVEN CHECKED THE THROTTLE CABLES AND THIS ISN'T THE PROBLEM
So as you can see I have a mystery on my hands, any ideas would be greatly appreciated.
Thanks!!!
I have a 1992 21' Thompson with a 4.3 Mercruiser. I have read a lot of the posts on this forum and I have tried everything suggested and still have the same issue. The engine idles great but as soon as you hit the throttle there is absolutely no power and it takes FOREVER to get the boat on a plane. Once on a plane it run great until you hit between 4200 rpm or WOT then the engine rpm fluctuates. I have tried everything that has been suggested below.
?Fuel condition. Type and Octane possibly old fuel - I RUN 92 OCTANE AND USE FUEL STABILIZER AND ADDITIVES FOR WINTERIZATION I ALSO DRAINED THE FUEL AND ADDED NEW FUEL SO THIS CAN'T BE THE PROBLEM
?Propeller pitch or diameter, damaged blades - BOAT RAN GREAT TWO YEARS PRIOR AND NEVER CHANGED THE PROP NO DAMAGE TO PROP AND I EVEN BOAUGHT A NEW PROP SAME PITCH AND DIAMETER SO THIS CAN'T BE THE PROBLEM
?Restricted fuel pickup tube or anti siphon valve Fuel System Test - RAN A FUEL LINE STRAIGHT FROM FUEL PUMP TO PORTABLE FUEL CAN SO THIS CAN'T BE THE PROBLEM
?Crankcase oil volume, high oil level can cause aerated oil and lifter collapse - CHANGED THE OIL MYSELF AND CHECKED AND RECHECKED OIL LEVEL SO THIS CAN'T BE THE PROBLEM
?Marine growth on hull and outdrive - BOAT ISN'T STORED ON THE WATER AND HAS BEEN WASHED AND WAXED (TO INCLUDE HULL) SEVERAL TIMES SO THIS CAN'T BE THE PROBLEM
?Wrong gear ratio in outdrive - BOAT RAN GREAT TWO YEARS PRIOR AND NEVER CHANGED THE THE OUTDRIVE ALTHOUGH IT HAS BEEN CHECKED AND SERVICED SO THIS CAN'T BE THE PROBLEM
?Restricted carburetor air intake (clogged flame arrestor) - CLEANED FLAME ARRESTOR AND EVEN RAN ENGINE WITHOUT IT SO THIS CAN'T BE THE PROBLEM
?Restricted exhaust system (broken exhaust shutters/flappers) in engine transom shield or drive - REMOVED SHUTTERS AND RAN (FOR TESTING PURPOSES ONLY) THEN REPLACED THEM SO THIS CAN'T BE THE PROBLEM
?Poor cylinder compression Compression Test - DID A COMPRESSION TEST ON ALL CYLINDINDERS AND THEY ARE FINE SO THIS CAN'T BE THE PROBLEM
?Carburetor defective, or wrong type. - REPLACED MERC CARB WITH BRAND NEW ROCHESTER CARB SO THIS CAN'T BE THE PROBLEM
?Fuel pump pressure and vacuum - DID A PRESSURE AND VACUUM TEST AND WAS WITHIN SPECS SO THIS CAN'T BE THE PROBLEM
?Boat overloaded, improperly loaded, or improperly trimmed. - HAHA YA OK....I WEIGH 175LBS I THINK I'M GOOD HERE
?Engine Overheating - THIS IS OBVIOUSLY NOT THE PROBLEM
?Engine timing and ignition system operation - I ADJUSTED THE TIMING AND REPLACED PLUGS, WIRES, CAP, ROTOR, DISTRIBUTOR PICK UP, COIL ETC. THEN I WENT THRU THE MANUAL AND DID ALL THE DIAGNOSTIC CHECKS AFTER REPLACING EVERYTHING JUST TO MAKE SURE I DIDN'T BUY ANY FAULTY PARTS SO THIS ISN'T THE PROBLEM
?Remote control cables and linkage for proper travel to open throttle plates fully. - I EVEN CHECKED THE THROTTLE CABLES AND THIS ISN'T THE PROBLEM
So as you can see I have a mystery on my hands, any ideas would be greatly appreciated.
Thanks!!!
