Fuel Carburater Question

[Clarida]

Hi everyone I have 4.3 Mercruiser and I have put a 4 barrel carb. I took the boat to test carb and I was able to run 26 knot but then it lost compression and I took her down to a lower Rpm and it would continue to operate but when pushing the for a higher rpm it would almost shout down until I would bring the speed down any clue Thanks

 

[kenny nunez]

Was the carburetor a marine version? If it was an automotive type then #1 it is not safe and #2 it is too lean.
Marine carburetors are designed so that if it “floods over” the gas stays inside the throttle body and not out and all over the engine which will cause a fire.

 

[stresspoint]

you may have a fuel blockage ,

is the fuel pump electric or is it the early mechanical type .

remove the fuel filter and check for water or debris.

 

[racerone]

??----How do you know it lost compression ?

 

[Scott06]

In addition to other comments what are you working on? year or preferably serial number on engine ?

What carb was put on - was this originally a 2 bbl carb and you converted it or you just put a new or reman carb on it to replace origi 4 bbl? Why did you replace carb- assuming if it was working ok you wouldn't have done that ?

What is your compression numbers?
what does the contents of your fuel filter look like?
what do spark plugs look like?
When was last time ignition system had any maintenance work done to it ?
Have you set/checked not only initial timing but total advance vs factory specs

 

[Scott Danforth]

Hi everyone I have 4.3 Mercruiser and I have put a 4 barrel carb. I took the boat to test carb and I was able to run 26 knot but then it lost compression and I took her down to a lower Rpm and it would continue to operate but when pushing the for a higher rpm it would almost shout down until I would bring the speed down any clue Thanks

How do you know it lost compression?