Fuel problem

[derekh]

Hi Folks,
I hope someone might offer advice.
The boat is an Antares 1080
After a long run, 30 miles plus, when the boat sits a day the port engine needs to crank for 15/20 seconds before it will fire up. On inspection the fuel filter pot on that side is 1/2 full of air. I suspect a few things.
Porus fuel line, leaky lift pipe or air being introduced from the return feed. Once the engines run, kamd44, they are faultless.
Any ideas greatly appreciated.
Derek

 

[Porthandbuoy]

Most likely air being introduced on the suction side of the lift pump. Unlikely to be a leak on the +ve pressure side or the diesel return line. Any sign of any diesel weeping from any joint or seal?

 

[derekh]

Thank you for replying.
no fuel leak. Im thinking porus fuel line enough to let a small amount of air in but no pressure to let fuel out.

 

[Boater Sam]

Thank you for replying.
no fuel leak. Im thinking porus fuel line enough to let a small amount of air in but no pressure to let fuel out.

Porous dip pick up tube in the fuel tank if they are separate tanks?

 

[lustyd]

no fuel leak.

If that's the case then where would the fuel go? Even if air gets in at the top of the filter housing, that wouldn't allow fuel to escape to anywhere. The outlet on filters is usually at the top so no way for gravity to pull the fuel out. It's theoretically possible it's syphoning out but not sure how or where it could be sucked to.

Possibly a blocked breather pulling a vacuum and sucking the fuel back into the tank?

 

[snowbird30ds]

Are there any filter housings in the system before the lift pump? What type and what level in relation to tank and engine?
CAV filters can be a bugger for air leaks if the top seal is replaced with an old one still tucked up in the recess, easily done if access and light is poor.

 

[lustyd]

CAV filters can be a bugger for air leaks if the top seal is replaced

Unlikely to be this since it only affects it when at rest and no fuel is leaking out of the system. A leaky seal at the top would only let air in at rest if the fuel was leaking from the bottom to make space for it. A leaky top seal would let air in while running, but OP said the engine works fine while running.

 

[derekh]

Porous dip pick up tube in the fuel tank if they are separate tanks?

Thanks for reply. I’ll pull it out and take a look.