twin mercruiser 340 not pulling gas from the tanks

[jo8330]

Ok so I have a 1985 chris craft commander 333 with twin mercruiser 340 inboards. Its been sitting for two years. The gas tanks were cleaned and drained when the boat was laid up . Basically the system is this. The lines come off the tank into eachother, and up to the water seperator, then the fuel pump pulls in from the separator sending it to the carb. I cant get fuel to the water separator. I ran both engines off a 5 gallon can (pulled the line off the water separator and put a hose on the separator into the 5 gallon can) it pumped fuel up from the 5 gallon can no problem. They are 100 gallon tanks on each side of the boat I have 12 gallons in each right now. Its kind of a long run and they were completely drained and the lines were blown out.....should my mechanical fuel pump be able to pull it up from the gas tank ? Its about a 7-10 foot run. Should I find a way to try amd prime it ? Not sure what to do......

 

[Grub54891]

You may need to add more fuel. 12 gallons may not be enough to reach the fuel pickups,if they are in one end of the tank and the boat is slanted away from them. Or the anti-syphon valve may be stuck. Let us know how it goes!

 

[jo8330]

I thought that too. The boat is tilted back a little bit but the pick ups are in the back of the tank. I guess the anti siphon valves are on the top of the tank where the connection for the line is ? I know what it is but I never had to mess with one. This has to be remedied fast boat is being launched friday

 

[Grub54891]

Yup,the syphon valve is at the top,unhook the line,unscrew the fitting and check/replace it. While you are there,see if the pickup in actually submerged in fuel.

 

[Scott Danforth]

sounds like a gummed up anti-siphen valve (check valve).