Fuel Venting Issue (causing incorrect fuel reading & motor to shut off)

gnc1017

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Carlyle Lake, IL
This past summer, we had two instances where our motor had shut off without warning. Initially thinking our sending unit was bad and we were out of fuel (more on that later), we finally found that the tank was no longer venting due to a clogged vent fitting filter screen.

We have a side-fill cap fuel system with the tank in the center toon and a carbon canister. From the tank, there are 2 vent hoses (one towards front and one towards rear of tank) that are Y'd together to a common vent hose under our port rear lounger (we have a RCW - center walk-out). This common vent hose connects to a check-valve assembly with another hose then dropping down from there to a carbon canister. The other end of the carbon canister vents through the deck floor below. My understanding is that this system is very typical on these newer boats (ours is a 2015). All of this on our RCW is located under and just behind our port lounger backrest (that backrest just pulls off as it was held on by Velcro).

The end of our vent hose has a fitting that is screwed from above to the deck and flush with the deck on the underside. Once removed, this fitting has a small round black cap that screws off and a fine mesh screen just inside. Our vent screen was clogged with a residue (we're not sure exactly what yet - possibly evaporated fuel?), preventing the tank from venting properly.

What transpired during operation was that the fuel tank would suck inwards due to the inability to vent - so much that the fuel level and gauge would still read quite high (would read ~ 7/8 full and then drop to ~5/8 after vented by removing the fill cap). This suction also in-turn even caused the sides of the tank to bend our fuel sending unit rod (this happened twice until we figured out what was really happening). Initially thinking we were fighting a bad fuel sending unit (until our second one also bent) we finally realized it was the venting issue that was causing the motor to shut down.

I'm not sure if they still install the fine mesh screen in the end of the vent hose, but I'm curious if anyone else has this fine mesh vent screen and if so, if it is also clogged from some sort of residue. Most owners likely wouldn't realize it as our motor-shutdown issue only occurred after a full tank and then some lengthened run time. What we also now realize is that the amount of venting that comes through the fuel filler cap when we remove it is significantly less than it had been so thinking we have had this problem for a little while. So if you also experience a ton of air when you loosen your fill cap, you may want to check this component. If you check your system for a fine mesh vent screen, please post back your findings (does it exist and if so, is it clogged).

Here are some pictures of what we found. I've also posted the pics in my profile Media.
 

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Interesting. I’ll have to check my GCW and see if I have this vent. I’ll pull it and check for cleanliness. I haven’t had any issues yet, but did notice last time I fueled up at marina, I had quite a vacuum built up when I opened my cap.
 
Thanks Semp! I'm figuring this to now be an annual maintenance item for us so very curious as to what you and others find.

Looking back, we had the big 'woosh' from the cap for quite a while and now it is so much better. I have to believe we aren't the only one that has/had this happen, whether they realize it or not.
 
I wws going to make a post about this yesterday bit didnt get around to it so I'll add to this one.

Just went through a very similar problem as this but was a bit bigger problem. Mine is a 2018. The vent you have pictured was partially plugged with sawdust from when the hole was drilled through the floor but...the hole was drilled right on top of one of the aluminum frame cross members. Not only was the tank not venting properly , the result of the vent being on top of the cross member was it acted as a ramp if you will and pushed water right into the vent line! And that siphoned lake water right into the tank. Not good! The charcoal filter was full of water and the vent line had water in it right up to the tank vent itself!

From day one it was difficult to get gas in the tank and I also got the "whoosh" when I'd open the cap and the last time the tank was sucked way in from the vacuum. After the boat dying a couple of times out on the lake , several tanks of gas full of water drained , and several filter changes , I have fixed the issue but what a pain it was!

Another thing...my fuel pick up in the tank is low enough that it can just about suck the tank dry. So every little bit of water was going right through the system and would fill the separator , fuel bowl , and reservoir at the fuel pump in no time.

The last time out I was able to fuel up with the gas nozzle at full speed and have no more signs of water getting into the system.

Your issue I would think more common than the problem I had but could be the cause of a lot of the problems some are having with the slow fuel fill.
 
Little-B, can you confirm that your 2018 still has the same vent line cap and fine mesh screen that ours has? I'm curious if this is still the current design or if improvements have since been implemented.

Also, from your indication of water intrusion through this vent, guessing you don't have the under-deck wave shield (and ours that has the shield doesn't have a risk of that issue)?
 
Yes I have the exact same vent. Mine wasn't gummed up like yours and the mesh was actually pretty clean I'm guessing from the bath it got every time I took the boat out!

I do have the wave sheild on mine too. Don't ask me how the water is getting there but the mis drilled hole is also right by the edge of the transom where it bolts to the underside. The wave sheild does have some minor gaps in that area so it's probably where it's coming from. Don't know if that's the norm or they got a little sloppy cutting out for the transom? The vent line needs to be towards the center of the boat/transom to keep it dry in my opinion. That and not having a cross member directing water right to it!
 
Yes I have the exact same vent. Mine wasn't gummed up like yours and the mesh was actually pretty clean I'm guessing from the bath it got every time I took the boat out!

I do have the wave sheild on mine too. Don't ask me how the water is getting there but the mis drilled hole is also right by the edge of the transom where it bolts to the underside. The wave sheild does have some minor gaps in that area so it's probably where it's coming from. Don't know if that's the norm or they got a little sloppy cutting out for the transom? The vent line needs to be towards the center of the boat/transom to keep it dry in my opinion. That and not having a cross member directing water right to it!

Thanks for following up Little-B. Since the vent line cap/screen appears common to several recent years, it will be interesting to hear if others are having any issues with gumming up/debris or water intrusion due to placement - or if ours are just isolated incidents.
 
Since I have not purchased my boat yet, I would be very interested as to how common and on what models the vents are positioned like yours.. Any chance of a word from Bennington?
 
GNC, thanks for taking the time to document, explain and provide pictures of the problem. I've got a 2016 GCW that has a similar if not identical setup but so far, no problems. That said, I think I'll try to take a closer look if weather permits before we put her to bed for the season.
 
Again, Would like to know what models use this system and also if the-little-B is running at speed or a slow mover.
Wondering is the water being forced up into the vent line and into the tank is caused by speed and is not experienced by slower boats with less HP..
 
I have the same little vent screen, and it was also partially plugged. However, even though I have cleaned and reinstalled it, I am still getting a significant amount of "vacuum" in the tank after running the boat for awhile. I am thinking of adding another vent between the tank fill and the vent assembly. I don't really want to run with the gas cap off or loose, although I am tempted to drill a hole in the cap and let it do the venting.
 

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Thanks for following up Little-B. Since the vent line cap/screen appears common to several recent years, it will be interesting to hear if others are having any issues with gumming up/debris or water intrusion due to placement - or if ours are just isolated incidents.
I purchased my boat back in 2016 (2221 SSX Bennington) and have had nothing but issues with water in my fuel tank since new. I Have had it drained twice now and finally enough is enough. After reading about others’ issues on this forum page where Bennington has owned up to the defect of where the venting was placed, it makes me feel slightly better. (I’m not out of the woods yet). They are sending me parts to reroute the vent out a side panel. Fingers crossed I can boat trouble free after it’s been moved!
 
That sounds like a long road. I hope this does the trick for you Saska-tooner. Kindly report back on whether it solves the problem or not. Maybe others can benefit from your outcome. Good luck!
 
I likewise am very interested in this outcome as I have had my boat die on me in the lake twice because of water getting in to the fuel tank and I’m at the end of my rope being stranded two time on a boat that is 60 days old
 
I wws going to make a post about this yesterday bit didnt get around to it so I'll add to this one.

Just went through a very similar problem as this but was a bit bigger problem. Mine is a 2018. The vent you have pictured was partially plugged with sawdust from when the hole was drilled through the floor but...the hole was drilled right on top of one of the aluminum frame cross members. Not only was the tank not venting properly , the result of the vent being on top of the cross member was it acted as a ramp if you will and pushed water right into the vent line! And that siphoned lake water right into the tank. Not good! The charcoal filter was full of water and the vent line had water in it right up to the tank vent itself!

From day one it was difficult to get gas in the tank and I also got the "whoosh" when I'd open the cap and the last time the tank was sucked way in from the vacuum. After the boat dying a couple of times out on the lake , several tanks of gas full of water drained , and several filter changes , I have fixed the issue but what a pain it was!

Another thing...my fuel pick up in the tank is low enough that it can just about suck the tank dry. So every little bit of water was going right through the system and would fill the separator , fuel bowl , and reservoir at the fuel pump in no time.

The last time out I was able to fuel up with the gas nozzle at full speed and have no more signs of water getting into the system.

Your issue I would think more common than the problem I had but could be the cause of a lot of the problems some are having with the slow fuel fill.
Really glad I found this post. Last two or three times out this year, I have noticed I can barely get gas to go into tank. Keeps tripping the nozzle as if it’s full. Gauge reads half full, but now I’m not sure. I need to try and find this vent and see if it’s clogged.
 
Mines at dealership being scoured over. Will post remedy… if it works. Mentioned some black cylinder by separator filter that leads to vent. Same thing?
 
I have a 2016 24SSRX bought brand new and have been wrestling with fuels issues from day 1. Bennington dealership kept telling me that it was the charcoal canister causing the venting issues. Last week, I "ran out of gas" twice on same weekend. First refuel held 12 gallons; second refuel held 13.5 gallons. And I am supposed to have a 24 gallon tank!!! I cant ever remember putting more than about 12 or 13 gallons in the tank. Either the build sheet is lying, or I have sending unit and fuel pickup tube problems. Love the boat, but the constant fuel issues push me to want to sell. Glad to read that Bennington has owned up to the problem. Wonder if they will offer some technical assistance so that I can take advantage of the full volume of the fuel tank size.
 
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I would document each fill. Video it where the tank pressure prevents more than 12 gallons Dealer needs to be pressed as well. Mine would take all 45 gallons no problem but very certain operating conditions like right turns towing tube or WOT to idle and sitting in slip if wake chop would bounce her around I think water was getting pushed up the the vapor vent fitting under decking. They did replace my charcoal canister as it was “ compromised”. I assume they have replaced yours?

attached is pic of new one
 

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My last trip I had an issue where the tank kept filling (pulled in about a mile after reading zero gallons, I was sweating bullets): 56 gallons in my 50 gallon tank. Then found the excess had somehow leaked out down the deck off the back. Did not come out the filler, same gas pump I had used Everytime before without issue and auto stopped when full, not this time. Only ran about a half hour after with no issues. No idea if related but more data points on fuel issues maybe faster we can find solutions.
 
My last trip I had an issue where the tank kept filling (pulled in about a mile after reading zero gallons, I was sweating bullets): 56 gallons in my 50 gallon tank. Then found the excess had somehow leaked out down the deck off the back. Did not come out the filler, same gas pump I had used Everytime before without issue and auto stopped when full, not this time. Only ran about a half hour after with no issues. No idea if related but more data points on fuel issues maybe faster we can find solutions.
That sounds no bueno.

These EPA fuel tanks have a lot of opportunities to fail, from clogged vent screens to water getting trapped in vent kinks. I haven't dug around in mine but I suspect there are some ball check or float valves integrated in the system as well, yet another opportunity to fail. Great when it works but when it fails it seems to cause bigger issues than it's trying to cure!

If auto is not kicking off then something is preventing fuel from coming up the sensing line telling the pump handle to click off. Seems like fuel is exiting the tank from another vent line below the fill neck - there might be a float valve that is stuck open allowing this to happen.

Again just a guess since I haven't torn my system apart yet.
 
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