Mercruiser unusuall Fault Found

[NIC SURRY]

Hi I thought I would share the fault that has caused me some grief,Mercruiser 140 runs pefectly on low revs pops and bangs above quater throttle,having changed all the electrical components,replaced head gasket,crack tested manifolds and elbow,overhauled carb it still missfired,my engine had been running with a 12v coil so I replaced like for like,it should have been a 9 volt coil and that a 12v coil ran OK with a 9 volt feed but when the resistor wire broke down and only fed 6 volts it started missfiring,its a bit like running an engine off the battery with no charging as the battery gets lower the engine starts to faulter eventually stalling.Now fiited new 9 volt coil and ballast resistor and it runs a treat,This was a bit of a weard fault and thought i'd share it as I nearly towed the boat out to sea to sink or burn it and I replaced a load of bits unnecessarily.The manual I had said no mention of 9 Volt Coil which was a great help. Thanks Bill for your help
Nic

[BILL BROWN]

Originally Posted by NIC SURRY

Hi I thought I would share the fault that has caused me some grief,Mercruiser 140 runs pefectly on low revs pops and bangs above quater throttle,having changed all the electrical components,replaced head gasket,crack tested manifolds and elbow,overhauled carb it still missfired,my engine had been running with a 12v coil so I replaced like for like,it should have been a 9 volt coil and that a 12v coil ran OK with a 9 volt feed but when the resistor wire broke down and only fed 6 volts it started missfiring,its a bit like running an engine off the battery with no charging as the battery gets lower the engine starts to faulter eventually stalling.Now fiited new 9 volt coil and ballast resistor and it runs a treat,This was a bit of a weard fault and thought i'd share it as I nearly towed the boat out to sea to sink or burn it and I replaced a load of bits unnecessarily.The manual I had said no mention of 9 Volt Coil which was a great help. Thanks Bill for your help
Nic

Its a pleasure to help, I have worked on M/Cruisers for more years than I care to mention and since I have retired its nice to help out others and keep my hand in, Any other problems let me know. Bill