carb spacer

[1977 SILVERLINE]

I am wondering if anyone has ever used a carb spacer for their rochester carb on their mercruiser. I am wondering if it would increase performance make it start easier and if it would prevent vapor locking? Thanks

 

[SDSeville]

As I mentioned earlier, it is likely not a vapor lock issue. I chased down what I thought was a vapor lock issue for a few years only to find I had a bad fuel pump. I taped the fuel line with heat tape, got a second blower and pointed it at the carb and fuel line, searched high and low for a spacer... I was discussing it with the local parts guy when I was looking for a carb spacer one day and he said "why would your boat all of a sudden develop vapor lock after 25 years?" Lucky for me I found the real problem (with the help of everyone on this forum) after seeing fuel go up the overflow tube from the mechanical fuel filter to the carb, flooding the carb and making warm starts very difficult. I am not saying that is your issue, but it is likely not vapor lock unless someone recently changed something on your boat to make it significantly hotter near your carb and fuel line.

Check your fuel pressure, fuel filters, rebuild carb,... The fact that you have an electric pump feeding the mechanical pump leads me to believe someone thought there was a fuel delivery problem at one time.

 

[1977 SILVERLINE]

I installed the electric fuel pump to try to resolve this hot start issue three years ago. My boat is a closed bow so the fuel tank is in the front. It is a 17.5 foot boat. The fuel pump is mounted on the engine it runs around the other side up to the front and into the sender which sucks from the top of the tank to the bottom. I guesstimate that the original fuel pump had to suck fuel approximately 23'. I installed the electric pump which has to suck fuel approximately 2' and pushes fuel the other 21'.

 

[SDSeville]

I never had any luck finding the spacer. I searched high and low including posting here. If you find one it should not be too expensive or hard to install. However, as I mentioned above, if it worked fine for many years, why would it develop vapor lock now? I guess with the new crappier gas anything is possible.

When was the last time the carb was rebuilt? How about new points, coil,...? Fuel filters clean? Fuel pressure? These are easy things to eliminate from your list of possible causes (and should be done periodically anyway) while you are chasing down the spacer.