Fuel Issues and Anti Siphon

[Stuartvaguy]

I have been experiencing a surge sometimes when I start my boat (99 mercruiser efi 5.0). I'm getting code for low fuel pressure. It always runs well after plane and even for extended periods. Sometimes stalls during plane. Was out on the water and once there start, stall, surge between 2000 rpm and very low rpm often dying altogether. I have read about problems with anti syphon causing this. Would removing the fuel cap altogether when this is happening rule out the anti siphon? Would the anti syphon be attached on one of the lines pictured or on the back/engine side of the tank? Thanks for any help you can give!

 

[Stuartvaguy]

The surging upon start never seems to occur upon first start. It used to do it about 1/10 starts after warm but seems to be getting worse and worse.

 

[Stuartvaguy]

During the surging at start I get beeping alarm, while at throttle to plane it's a solid alarm. Have replaced oil pressure switch, alternator, and starter. Also new fuel water separator filter. Found

 

[Bondo]

Would the anti syphon be attached on one of the lines pictured or on the back/engine side of the tank?

Ayuh,..... Welcome Aboard,..... The anti-siphon valve IS the hose barb where the gas line to the motor, comes outa the tank,.....

 

[alldodge]

What is the motor serial number?
Do you know what the fuel pressure is from idle to WOT?

 

[Bt Doctur]

Never heard of a fuel pressure sensor on a throttle body engine? What about the fuel filter?

 

[Stuartvaguy]

0l340610 is the sn. I don't know much about putting a pressure gauge on this the low fuel pressure warning just came from the diagnostic scan. I have changed the separator fuel filter.

 

[tank1949]

Pickup tube may have filter inside. Trust me! One of mine was totally clogged up.

 

[Stuartvaguy]

That's what I was thinking. Would that be more on the engine side of tank or would that be the small hose by the large one pictured above?

 

[achris]

Pull the pick up out of the tank. Remove the filter from the end of the pick up and throw it in the rubbish bin. Refit the pick up...

Chris...

 

[Stuartvaguy]

Ok so I pulled the tube and filter had already been removed. However, with the anti syphon I am having to blow as hard as i can to get even a trickle of air to pass through. Shouldn't the ball be moving easily and allowing flow through this?

 

[alldodge]

Ok so I pulled the tube and filter had already been removed. However, with the anti syphon I am having to blow as hard as i can to get even a trickle of air to pass through. Shouldn't the ball be moving easily and allowing flow through this?

Yes it should be very easy in the flow direction

 

[Stuartvaguy]

All I can find locally is one without anti syphon. Would it be bad to use an open one?

 

[Stuartvaguy]

Scratch that, I just read of the possible ramifications of doing this. I'll wait till I can get the part.

 

[alldodge]

Yes, you can use one for testing that is just a open barbed fitting. While its not approved, its ok for testing. Only issue comes is if there is a leak in a fuel line and it drains the tank into the bilge

 

[Bondo]

Yes it should be very easy in the flow direction

Ayuh,..... If I remember right, it should be 3 to 5 psi,......

 

[kenny nunez]

Just be sure to get a brass anti siphon valve. The aluminum ones are known to distort and restrict the check ball movement.

 

[alldodge]

Just be sure to get a brass anti siphon valve. The aluminum ones are known to distort and restrict the check ball movement.

You sure about that?
Marine tank manufactures use aluminum valves on aluminum. There is also the dissimilar metal issue with brass and aluminum

 

[Stuartvaguy]

Thank you all for your help. I tried the open tube and went out and tried as hard as I could to get it to replicate and it ran beautifully. I've replaced a lot of parts on this new to me boat with 300 hours and now I'm so excited we can finally enjoy it and I can relax. Until next time lol.