Nicolai123
New member
Hi all
I have a Mercruiser 4.3L MCM (carburetor + seawater cooled) with an Alpha 1 Gen 2 drive.
Engine serial: 0L063706
Drive serial: 0L122486
I'm preparing my boat for summer. This Saturday I replaced fuel and oil filter and engine oil. The engine started and ran perfectly fine multiple times both before and after doing that. Sunday I went to replace the impeller. This is the guide that I followed: https://www.youtube.com/watch?v=wqkLEvquA-s. I took the lower unit off, impeller housing off, put new one in (in correct orientation and with the key that locks it to the shaft in place) with new gaskets and metal plate. I put the o-ring for the oil on and then I put on the lower unit again and filled it with drive oil.
Since then, the engine hasn't been able to start properly. I can get it running if I give it full throttle and after 10 seconds or so it almost idles, but sounds very rough and there's an alarm tone going off. Oil pressure is normal on the gauge and the starter runs fine. I've checked there's fuel flow to the carb. I've tried spraying starter fluid into the carb, still the same. I'm not sure the impeller is picking up water, at least I haven't been able to see water leaving the engine (but I've only ran the engine for a few seconds at a time), but that shouldn't affect whether the engine can run properly surely?
Carburetor was cleaned by a mechanic last summer. I flushed the cooling system with coolant before storing for winter.
Any ideas? I'm desperate
I have a Mercruiser 4.3L MCM (carburetor + seawater cooled) with an Alpha 1 Gen 2 drive.
Engine serial: 0L063706
Drive serial: 0L122486
I'm preparing my boat for summer. This Saturday I replaced fuel and oil filter and engine oil. The engine started and ran perfectly fine multiple times both before and after doing that. Sunday I went to replace the impeller. This is the guide that I followed: https://www.youtube.com/watch?v=wqkLEvquA-s. I took the lower unit off, impeller housing off, put new one in (in correct orientation and with the key that locks it to the shaft in place) with new gaskets and metal plate. I put the o-ring for the oil on and then I put on the lower unit again and filled it with drive oil.
Since then, the engine hasn't been able to start properly. I can get it running if I give it full throttle and after 10 seconds or so it almost idles, but sounds very rough and there's an alarm tone going off. Oil pressure is normal on the gauge and the starter runs fine. I've checked there's fuel flow to the carb. I've tried spraying starter fluid into the carb, still the same. I'm not sure the impeller is picking up water, at least I haven't been able to see water leaving the engine (but I've only ran the engine for a few seconds at a time), but that shouldn't affect whether the engine can run properly surely?
Carburetor was cleaned by a mechanic last summer. I flushed the cooling system with coolant before storing for winter.
Any ideas? I'm desperate
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