"Mercruiser 470 4 cylinder wit
"Mercruiser 470 4 cylinder with freshwater cooling (has heat exchanger).
History, former owner rebuilt engine 2 years ago. Noted that carb may have had a problem on last time in the water. Boat setup for 2 years. I have just now placed new outboard impeller pump and motor cooling fine. Engine idles great
but when you try to accelerate it intermittently backfires. Seem to do it less after it warms up. Have not put in the water yet, just using muffs to test run.
I noticed NO pulse of gas out of accelerator pump so pulled the top off the carb. Someone had apparently been in the carb and somehow left the internal linkage off the accelerator pump. Eventhough I thought I had found the problem
I went ahead and pulled the two main jets(they were not all that bad) and cleaned. I pulled the power jet and it was blocked so I cleaned it out good.
I blow carb cleaner in the main jets and see small stream out some holes in the top of the ventura ( I guess this is what I'm looking for). I re-assembled and have good accelerator pump stream now. Strangely enough my problem is stil
there maybe not as bad when engine is warmed up.
So my question...which of the following should I persue?
1)I did not pull the ventura off and am now worried that there could be a blockage in one of them eventhough I could spray carb cleaner thru main jets and get spary out of the small holes in the TOP of the ventura.
2)Since the previous owner noted a carb problem of some sort after the engine had been rebuilt, Could it be that my problem is solely timing? I don't have timing light so didn't want to bother unless I eliminated all else.
3)Lastly, I have a very strange rattling noise in the exhaust in the outdrive. It sounds to be on the left side mostly. The small water spray exhaust hole on the left side is were it sounds like it is coming from. I can put my thumb over the hole and the noise goes away, in fact if I cover the right side hole the noise almost goes away too. I also have a very small (only a drip) water leak on top edge of exhaust rubber pipe eventhough clamps are now tight. I have read some threads about flappers breaking off and such.
If I can get the boat to not hesitate (in most cases it backfires) it should be a good engine because it idles very smooth. Please help."
"Mercruiser 470 4 cylinder with freshwater cooling (has heat exchanger).
History, former owner rebuilt engine 2 years ago. Noted that carb may have had a problem on last time in the water. Boat setup for 2 years. I have just now placed new outboard impeller pump and motor cooling fine. Engine idles great
but when you try to accelerate it intermittently backfires. Seem to do it less after it warms up. Have not put in the water yet, just using muffs to test run.
I noticed NO pulse of gas out of accelerator pump so pulled the top off the carb. Someone had apparently been in the carb and somehow left the internal linkage off the accelerator pump. Eventhough I thought I had found the problem
I went ahead and pulled the two main jets(they were not all that bad) and cleaned. I pulled the power jet and it was blocked so I cleaned it out good.
I blow carb cleaner in the main jets and see small stream out some holes in the top of the ventura ( I guess this is what I'm looking for). I re-assembled and have good accelerator pump stream now. Strangely enough my problem is stil
there maybe not as bad when engine is warmed up.
So my question...which of the following should I persue?
1)I did not pull the ventura off and am now worried that there could be a blockage in one of them eventhough I could spray carb cleaner thru main jets and get spary out of the small holes in the TOP of the ventura.
2)Since the previous owner noted a carb problem of some sort after the engine had been rebuilt, Could it be that my problem is solely timing? I don't have timing light so didn't want to bother unless I eliminated all else.
3)Lastly, I have a very strange rattling noise in the exhaust in the outdrive. It sounds to be on the left side mostly. The small water spray exhaust hole on the left side is were it sounds like it is coming from. I can put my thumb over the hole and the noise goes away, in fact if I cover the right side hole the noise almost goes away too. I also have a very small (only a drip) water leak on top edge of exhaust rubber pipe eventhough clamps are now tight. I have read some threads about flappers breaking off and such.
If I can get the boat to not hesitate (in most cases it backfires) it should be a good engine because it idles very smooth. Please help."