1978 BMC Bonanza with Mercruiser 140 Engine bog - Need help - Fuel or Ignition Issues ?
Recently, I bought a 1978 BMC Bonanza that has a Mercruiser 140 in it. Over the winter, I drained the gas and rebuilt the carburetor and installed new fuel filters. I changed the engine oil and filter and installed a new battery.
This past weekend, I was finally able to get it in the water and test everything out. I am having a problem with it and am looking for any help you guys may have to offer.
The engine starts right up (now - after the new battery was installed) and seems to idle and run as expected. We took it up river for about 10-15 minutes at a steady throttle about 1/2 to 3/4 doing 30MPH or so. It runs along just fine, but then after about the 10-15 minute mark the engine seems to start struggling and bogging. Without touching the throttle, it will start bogging down and then ultimately cut out. After that, it is difficult to start, if at all. We ended up letting it sit for 20-30 minutes and then it started right up after that. We went through this exercise several times that day.
At this point, I am not sure if this is a fuel related problem or an ignition problem related to heat. I am getting ready to replace the plugs, condenser, wires, cap, rotor and the coil...or I have also thought about getting one of those electronic ignition conversion kits.
Any advice or guidance you guys have to offer will be GREALTLY appreciated. Thanks in advance for your help.
Recently, I bought a 1978 BMC Bonanza that has a Mercruiser 140 in it. Over the winter, I drained the gas and rebuilt the carburetor and installed new fuel filters. I changed the engine oil and filter and installed a new battery.
This past weekend, I was finally able to get it in the water and test everything out. I am having a problem with it and am looking for any help you guys may have to offer.
The engine starts right up (now - after the new battery was installed) and seems to idle and run as expected. We took it up river for about 10-15 minutes at a steady throttle about 1/2 to 3/4 doing 30MPH or so. It runs along just fine, but then after about the 10-15 minute mark the engine seems to start struggling and bogging. Without touching the throttle, it will start bogging down and then ultimately cut out. After that, it is difficult to start, if at all. We ended up letting it sit for 20-30 minutes and then it started right up after that. We went through this exercise several times that day.
At this point, I am not sure if this is a fuel related problem or an ignition problem related to heat. I am getting ready to replace the plugs, condenser, wires, cap, rotor and the coil...or I have also thought about getting one of those electronic ignition conversion kits.
Any advice or guidance you guys have to offer will be GREALTLY appreciated. Thanks in advance for your help.
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