loss of gas prime?

[oddysea1]

The boat is a 1989 18ft.wellcraft with a built in plastic gas tank. The gas line and antisiphon valve was replaced and the tank was cleaned and drained. The engine is a 2001 150h.p. johnson ocean pro.My question is this, each time I pour fuel into the tank the engine starts right up, afterwards however 5 minutes into running she stalls and it takes some time to restart. Once started after this point she runs great until the next gas fill.The symptoms occur all over again each time. I am placing 10-15 gallons at a time and the tank stays 3/4 filled.Could this be coincidence or is there a possible pressure loss when the gas cap is removed?Thankyou Andy

 

[Georgesalmon]

Re: loss of gas prime?

Check out your tank vent.

 

[Silvertip]

Re: loss of gas prime?

There is no pressure in a fuel tank. Fuel is sucked from it by the fuel pump. If there is an air leak in the fuel line or fittings between it and the engine, you may have some running issues or fuel leakage. Since you messed with the anti-siphon valve, you may have broken or cracked the dip tube in the tank. Adding fuel brings the level above the break/crack so the engine runs fine. once fuel drops below the crack the engine has trouble picking up fuel until the line is full and it runs until you shut if off again.

 

[oddysea1]

Re: loss of gas prime?

The engine runs fine after the initial fill problem. Although I keep the tank generally 3/4 it has dropped well below that with incident.I replaced the anti siphon valve and hose because of age.I was very careful not to stress or crack anything.The problem occurs only after a fill up and lasts several minutes and then the engine runs fine, until the next fill.As for tank vent I will give that a inspection.Thankyou for your help,I have been on this site on several occasions and the advice has been spot on. Thank you Andy