Moeller tank venting

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Roberta
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Moeller tank venting

Post by Roberta » Thu Jul 26, 2012 2:32 am

I have a new Moeller portable 3 gal. tank that doesn't seem to vent properly. It has that new EPA vent on the filler cap. Seems the fuel pump on my little Merc 110 can't suck the vent valve in enough and the engine starves and quits after a while. Then the tank needs to be vented by pushing in on the little button. Then I can reprime and start the motor again. It will run until negative pressure exceeds the pump capacity and the cycle resumes. The button is turned CC to open the vent, but still can not vent properly. I understand this is a problem with these tanks. Has anyone modified the vent to work better besides drilling holes in the tank or cap? I would prefer to be able to seal it up for transporting, so I don't want to drill any unsealable holes if I don't have to.

Thanks,

Roberta :D
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

Gunner
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Re: Moeller tank venting

Post by Gunner » Thu Jul 26, 2012 2:41 am

If you are using the portable tank style fuel line, see if you have any tight turns that you may have overlooked. This could be reducing the flow.

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Roberta
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Re: Moeller tank venting

Post by Roberta » Thu Jul 26, 2012 5:55 am

The turns are pretty wide and the hose is not very long. I'm pretty sure it is a venting problem as the tank gets sucked in until I vent it manually. Then the tank expands again as the air is allowed back in.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

Gunner
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Re: Moeller tank venting

Post by Gunner » Thu Jul 26, 2012 6:14 am

If I was in your case and have not removed the fill cap completely and tried to run the boat, then the next step would be to do this with the present setup. If the engine quits again, then try another line with a new ball on it. Isolate the problem and the exterior components.

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Roberta
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Re: Moeller tank venting

Post by Roberta » Thu Jul 26, 2012 7:10 am

Yes we have run the motor with the fuel cap off. It is a tank vent issue, not the hose. If the hose or the fuel pump were bad, I doubt there would be a large vacuum in the tank. There wouldn't be a vacuum or the hose would just collapse. It is the tank vent. Just wondering if anyone has modified these vents.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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ttownshaw
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Re: Moeller tank venting

Post by ttownshaw » Thu Jul 26, 2012 8:14 am

I'm thinking it is a faulty vent...just my opinion.
Bill

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Roberta
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Re: Moeller tank venting

Post by Roberta » Thu Jul 26, 2012 8:29 am

There's been a few complaints regarding these tank vents. Moeller made the vent so a certain amount of negative pressure is required to open it. That way the gasoline vapors don't just freely vent to the atmosphere as they could in older style tank vents. This is supposed to keep the environment safer. I'm guessing smaller, older motors just don't have the oomph in the fuel pump to overcome the vent. I was just wondering if someone had this problem and found a fix that would still allow the vent to be closed so fuel would not spill when tipping the tank during removal and transport. Some people have drilled holes in the tank, but that would allow fuel to spill out in the right orientation. Not a very good fix. I may just look around for an older style 3 gallon tank with the older style vent cap.

Thanks,

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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Bill Edmundson
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Re: Moeller tank venting

Post by Bill Edmundson » Thu Jul 26, 2012 8:56 am

Think Bill S is on it. The tank walls should not suck in before the vent opens.

Bill
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Roberta
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Re: Moeller tank venting

Post by Roberta » Thu Jul 26, 2012 9:35 am

I'll write to Moeller and see if they can send me a new cap.

Roberta
Roberta "Queen of the Boat Builders"
Built Zip "Oliver IV", Super Spartan "Jimmy 70", and Torpedo "The Glen L".

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