Fuel Filter Bowl Full or Not

[WICKER55]

I have a 2007 Mercury 60 hp EFI. The fuel bowl starts out full after you prime the bulb until firm and once the engine starts the bowl begins to empty. The faster the RPM the faster it goes down. Many people say if this is happening you are sucking air somewhere prior to the bowl. The marine mechanic says it’s normal, it draws the fuel it needs. Any comments?

 

[garbageguy]

...The faster the RPM the faster it goes down...

what goes down?
does it run OK at speed under load?

 

[dingbat]

Many people say if this is happening you are sucking air somewhere prior to the bowl. The marine mechanic says it’s normal, it draws the fuel it needs. Any comments?

Are we talking carb bowl or fuel filter?

Carb bowl: perfectly normal. Level is determined by float setting

Fuel filter: could be sucking air.. how old are the fuel lines? Hose clamps or proper fuel line clamps?

Could be a flow restriction… under sized fuel lines, partially plugged screen on pickup in tank, dirty filter, sticking anti-siphon valve, etc.

Could be a weak fuel pump

 

[WICKER55]

The level of fuel in the fuel bowl Goes down till there isn’t any visible fuel in the bowl. All fuel lines have been replaced from the pickup screen to the engine and a new low pressure fuel pump has been installed. And yes it does bog down and miss at speed and under load. Mechanic says no problem, I’m kind of leaning otherwise.

 

[racerone]

Saw that on motors 50 years ago.----I was never worried.----Explained it was normal to many owners.----Do some more trouble shooting.

 

[dingbat]

All fuel lines have been replaced from the pickup screen to the engine

Hose clamps or proper fuel line clamps? Hose clamps are known problem areas.

Onboard fuel filter been replaced?

Remove fuel line from low pressure pump and replace with a short piece of hose dropped into a gallon of premix and run it.

This eliminates or confirms a problem in the fuel delivery system between the fuel tank and fuel pump.