Gas in the vapor tube
 

I've got a '96 Formula 336 SR1 with Merc HP500s. On the port side engine I see a clear liquid running up the vapor tube from the fuel pump to the flame arrestor after the engine has been running for an hour or so. I assume this is gas I see. Once this starts to happen the engine is very hard to start once shut off.

Engines are stock with the seawater mounted fuel pump. I've decided to replace the fuel pumps with the standard merc pump but I wanted to ask the experts if the fuel pump is the cause of the problem. I've read about vapor lock problems and wanted to know if that could be the problem as opposed to bad fuel pumps. Engines have stock carburetors.

Any help and advice is greatly appreciated!

Does it smell like gas? The diaphram in the fuel pump has ruptured. Replace it before running it anymore. You also should also take that time to replace the gear lube in the pump housing as they seem to get a little fuel mixed in with the lube. I used to change my lube 1-2x /yr. Fuel doesn't have much lubricating properties.

STOP,DO NOT START THE ENGINE.the diafram in the fuel pump has ruptured,this is dangerous.replace the fuelpump and change the engine oil.the reason it is hard to restart is the excess fuel in the intake charge.also,make sure to add some oil in the well on the seapump if the pump runs off the seapump.

oops,looks like us1 fountain beat me to the punch.

How do you replace the lube in the fuel pump?

the lube is in the housing the fuel pump mounts to, when you pull the fuel pump you will see it, get a small suction device with a hose and put it down in the housing and suck out the oil. I'm not sure what merc puts in it, but I just use engine oil, seems to work fine.

Fixx
 

make sure its gas and not water,either way it needs to be replaced,the oil that goes in the sea pump is merc hp lube,make sure you flush alll the gas or water out of it or you will be replacing it in the future..i have the same boat but a little more hp....