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Auxilliary Fuel Tank Venting - RSV with Hannigan Conversion


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Looking for some help understanding the venting of the auxiliary fuel tank on a Hannigan conversion. If I fill the auxiliary fuel tank on a hot day, gas expands and spills near right, rear wheel. Noticed today that filler pipe attaches to neck of tank with a radiator type hose. Upper band clamp was hand tight, and this is where fuel leaks. Bottom band clamp is very tight. Tightened the upper clamp today to stop the leaks, but now concerned about where fuel will expand since I removed this outlet. Is there some other venting. Does anyone know? Thanks!

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I do not have a conversion but I run an auxiliary tank on both of my MCs. Both have a vent at the top of the fill neck. I ran a hose, vacuum type, from that nipple to the back of the rear fender. I am not sure how your tank is made. There has to be a vent somewhere or a vacuum will be created and either collapse the tank (has happened on MC tanks) or the fuel flow will be stopped. Maybe the cap is vented. My caps are not vented since I have the vent port.

 

Is the fuel dripping directly onto the pavement or dripping into the trunk then leaking to the pavement. Are you sure the fuel was coming out of the area you tightened. Check for a venting tube. It just does not sound like nor make sense that the part you tightened was designed to be loose and used as a vent.

 

You might just not fill the tank to the top. Maybe leave an inch below the fill neck. As far as venting if overflow is not an issue a vented cap can be purchased. SandStorm, spunaluminumgastanks.com, is one source since Coyote seems to be gone.

 

If there is no other vent you probably can add one into the fill hose then attach a small hose to it as I did then run it out of the compartment to the rear with enough length so overflow will clear the trike but not end up on the wheels.

 

When I visited Hannigan about possibly purchasing a sidecar I inquired about an auxiliary tank. They told me the stopped putting them in their conversions and sidecars. Reason given was fumes. I am not sure that was the reason it was more than likely because of liability.

 

I'd give them a call.

 

If you can't resolve the issue send me a picture of your tank set up. Include the top fill area and where the filler hose attaches to the tank. Also the cap.

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I have had the same problem a few times, I found that only putting 4 gal. of gas in that tank stops leaking on floor. I believe the tank is only designed to hold 4 gal. not to be filled up.

 

Craig

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More than one Hannigan owner has told me they gets leaks on the floor if they fill the auxiliary tank. Bet everyone has leak at the same spot. This band clamp is right below the fill cap. The band clamp below it is tight, so hose is not going anywhere. Yes, only putting 4 gallons avoids spills, but it doesn't get rid of smell or evaporation. Afraid if I tighten clamp then I will get tank damage or impact fuel transfer to main tank. Need to talk with Hannigan, but I'm ready to go on a trip and don't want to do this right now. Set clamp back the way it's been for 10 years. The more folks I hear from the more I'm convinced Hannigan did this on purpose.

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I understand the frustration.

 

I do not understand why a non vented cap along with a tank equipped with a vent nipple on the fill neck with a hose attached to it then vented down and to the outside wasn't used.

 

If the way it sounds is their idea of venting no wonder they had trouble with fumes in the sidecar rigs.

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I don't think he makes them anymore. it's been a few years since i got my tank from him, he even installed it for me. Great job from a great guy.

 

 

 

 

 

I didn't know Carbon One made a tank. I have some stuff from him and it is good. I would have bought my RSV auxiliary tank from him if I would have known.
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Leo, I have pictures of a CarbonOne aux tank while it was being built, Jeannies trike was the R&D trike used to design the tanks Larry built. I worked with him during the development phase. Jeannies tank holds 7.5 gallons and does not leak or smell. 13.5 gallons total capacity! The tanks Larry sold to the public were Shrunk a bit to make the production tank kits easier to build and install.

I don't know the Hannigan design but Larry's tanks have internal baffles and the vent line fitting is installed in the top of the tank so fuel slosh does not fill the vent line. The hose rises before turning down and exiting near the rear axle.

 

Leo, if you want to see some pictures I will post them.

 

Sent from my SM-N920V using Tapatalk

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Hi Jay, I'm on vacation in NH for a couple more weeks. I triked up here. Would be interested in seeing photos of Larry's design. Not sure I'm going to change anything, but

would be interested in knowing what's out there. Sounds like Larry did some fine work. Thanks!

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