RPM's have dropped from 4800 to 4200 at full throttle
#1
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Location: Louisville Ky
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RPM's have dropped from 4800 to 4200 at full throttle
I have 1999 Colbalt with a 454 Mag EFI that has 300 hours of run time. I've only had this boat for 3 months and the first time I had it out on the water the max RPM"s were 4800. Now after have it out over 8 times the RPM's are down to 4200. No misfires or unusual running of engine. I have replaced the gas/water separator and cleaned the flame arrestor(was pretty dirty). The plugs showed signs of the engine running a bit rich and had some signs of wear. I have a new set of quick burn plugs ready for install.
Is their anything else I can check to rid this problem?
Is their anything else I can check to rid this problem?
Last edited by Colbaltmania; 08-10-2011 at 06:28 AM.
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I have 1999 Colbalt with a 454 Mag EFI that has 300 hours of run time. I've only had this boat for 3 months and the first time I had it out on the water the max RPM"s were 4800. Now after have it out over 8 times the RPM's are down to 4200. No misfires or unusual running of engine. I have replaced the gas/water separator and cleaned the flame arrestor(was pretty dirty). The plugs showed signs of the engine running a bit rich and had some signs of wear. I have a new set of quick burn plugs ready for install.
Is their anything else I can check to rid this problem?
Is their anything else I can check to rid this problem?
#3
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Do you leave the boat sit in the water? If not, you are probably down a cylinder. Could be a plug, wire, or worse. Sometimes it is hard to hear or feel a miss on a boat.
#4
21 and 42 footers
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I lost a cylinder and it did exactly what you describe...didn't sound too bad until you really paid attention. Could be a plug wire...or worse.