Fuel Tank Venting in Stingray I/O

[JDusza]

Got a call to help a friend with his Stingray. Not sure what year. It has a Volvo-Penta 3.0 L as the power.
He is experiencing fuel splashing back through the filler neck when fueling and random stalling at high speed.
The symptoms, to me, indicate a poor fuel tank vent.
Can anyone and help me out for what I;m looking for and comment on how a Stingray vents its tank and where I might find the vent through the hull?
Thanks,
J

 

[briangcc]

It *may* be integrated into the filler. It *may* be a separate fitting elsewhere on the boat.

Without pics, difficult to determine.

 

[flashback]

Open the fill cap when this happens..

 

[JDusza]

Thank you. You always help. I did find it.
It is an independent hose about 5/8 diameter which runs parallel with the fill hose. The outlet to the atmosphere is integrated with the fill neck. It is a square opening just before the big drop into the tank.
I removed the vent hose from the fitting, made sure it was clear. I made sure the fitting was clear.
No blockage issues found.
Given the vent is beneath the fill cap, yes, crack the cap.
Thanks,
J

 

[ESGWheel]

If I may, something still does not seem right. I thought the suggestion to crack the cap was a troubleshooting measure > with the cap ‘cracked’ it if now runs ok there is an issue with the venting, probably in the cap. I did not take it to mean drive around the boat with the cap partially open. That seems wrong if not dangerous. Am I missing something?

 

[KJM]

If I may, something still does not seem right. I thought the suggestion to crack the cap was a troubleshooting measure > with the cap ‘cracked’ it if now runs ok there is an issue with the venting, probably in the cap. I did not take it to mean drive around the boat with the cap partially open. That seems wrong if not dangerous. Am I missing something?

I was thinking the same thing. How does it vent if its below the cap? A loosened cap will let rain and splash water into the tank.

 

[flashback]

You guys are right, it is just a trouble shooting procedure not a permanent fix. All it does is tell you that the tank isn't venting as designed.. I've not experienced an integrated system as op described..

 

[ESGWheel]

My Larson has an integrated system by Perko
The venting is done thru the cap - it’s that smallish round device in the pic
For the OP - suggest getting a replacement cap

 

[JDusza]

So, ... I looked sat the cap. It seems solid. I don't see any holes or overlapped covers, check valves, or anything that indicates this cap vents.
So, I'm back to the original question, how does a Stingray vent? When the vent tube comes up alongside the fill neck and comes together in the filler neck fitting, how does the tank vent when the cap is tight? Where does the fitting vent go on a Stingray?
Thanks,
J

 

[ESGWheel]

Frankly I have not studied it that closely before. When I was leaning over the side of the boat to take the pic it was not obvious as to path thru the cap to me either. I do carry at spare aboard and when I am back on my boat, I will pull it out and investigate and post.
Regardless, it does indeed vent somehow. So, for your friend, if he bought a new one and it turns out not the issue, at least he will have a spare. I never did carry a spare cap until I was talking to a guy at the dock fueling station that said something like there are a half dozen caps below the pier. Probably a joke but made me think.

 

[ESGWheel]

So, ... I looked sat the cap. It seems solid.

Back at the boat and took out my spare cap. It does vent with a clever design. I did a write up and posted it here link,

 

[KJM]

So, ... I looked sat the cap. It seems solid. I don't see any holes or overlapped covers, check valves, or anything that indicates this cap vents.
So, I'm back to the original question, how does a Stingray vent? When the vent tube comes up alongside the fill neck and comes together in the filler neck fitting, how does the tank vent when the cap is tight? Where does the fitting vent go on a Stingray?
Thanks,
J

Is it possible that someone replaced a venting type cap for a regular non venting cap and thus it no longer vents as designed?

 

[dingbat]

Here is your vent.
One on each side

 

[ESGWheel]

One on each side

Unless they have different designs, turns out there are 4
this is one of the photos i took when dissecting these to figure out how they work…