Fuel bladder/I V bag plumbing
#1
Junior Member
Thread Starter
Fuel bladder/I V bag plumbing
Hello, I'm installing a fuel bag in my 43" V hull, powered by a 26cc Zenoah. I've got everything done, but the plumbing. Do I need a fuel pump now? I was under the impression that it would not, but then started seeing mixed answers to this question. And also would like to know about the primer/return line's placement. Any help would be greatly appreciated and thank you.
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CptnCR (11-22-2021)
#3
Junior Member
Thread Starter
So can I do away with the primer bulb. If there is no return line going into the bag. Well there are two connections on the bag ,but I thought one went to the filler plug. Thanks for replying though.
#4
The integral pump will pull more fuel than the engine and carb actually can use so, unless you want to waste a lot of fuel that will be dumped into the bottom of the boat, you will need the return line. This is the big difference between a gas and nitro engine. In a nitro engine, the needle valve restricts the fuel flow into the carb to just what the engine can actually use, the fuel being pushed to the carb by exhaust pressure. The Zenoah integral pump actually overloads the carb with pressurized fuel. This pressurized fuel is then "metered" by the needle valve as it only allows through the amount of fuel the engine can actually use. Any excess fuel is then returned to the bag for reuse. This is the same principle used in a fuel injected engine used in your car or truck, but not in a carb equipped engine. That's a whole different can of worms
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CptnCR (11-23-2021)
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CptnCR (11-24-2021)
#7
Junior Member
Thread Starter
Plug one of the outlets on your IV bag, you only need one. I run one line from the bag to the carb, with a T in the middle. On the third leg of the T, I add a short piece of tubing and a fuel dot. Easy peasy.
With that said, I usually find hard tanks easier to fill and use.
With that said, I usually find hard tanks easier to fill and use.
#8
My Feedback: (10)
It will be a bit lighter, those tanks you have shown are also a bit heavier than most. IV bags have their place, and work fine, I just find them to be more of a PITA than they're worth for me personally. You have to be sure to burp ALL of the air out of your bag before you run though, which usually involves standing the boat on its bow, allowing the air to rise as you squeeze the bag, then capping it back off... it can be a bit tricky to get used to, and it's the main reason I've swapped my boats running bags back over to hard tanks.
#10
Junior Member
Thread Starter
It will be a bit lighter, those tanks you have shown are also a bit heavier than most. IV bags have their place, and work fine, I just find them to be more of a PITA than they're worth for me personally. You have to be sure to burp ALL of the air out of your bag before you run though, which usually involves standing the boat on its bow, allowing the air to rise as you squeeze the bag, then capping it back off... it can be a bit tricky to get used to, and it's the main reason I've swapped my boats running bags back over to hard tanks.
#11
Junior Member
Thread Starter
Ok, so my bag i bought from gizmomotors has two ports on one end and I think I figured away to keep bubble from sucking down in to the bag when I'm filling it.(I just have a homemade squirtbottle). I put a check valve in line from the filler cap to the bag on one port and the other to the carb and no return. The line the was on the primer is still hooked up with a pug in it. After I filled up the bag I just popped out the plug and pumped the primer and the residual air bleed out and its now primed.