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Discussion Starter #1
I just recently installed an auxiliary tank in my bed plumbed into the filler neck of the truck via an RDS gravity feed kit. I have an DeeZee vented fuel cap on one side of the tank, and a 1/2" npt rollover vent valve on the opposite side vented to atmosphere. The problem I'm having is the tank is building what I would think is too much internal pressure. I realize that the fuel will expand when its warm and build pressure in the tank and its not necessarily a bad thing but the last few times Ive taken the fill cap off the pressure is high enough that it will lift the cap and my hand off the tank about 6". I will say this tank isnt a mass produced name brand tank, it is a home made that I purchased from someone. It also doesnt seem to want to gravity feed any fuel when there is pressure in the tank which is odd to me because i figured the pressure would help push the fuel out of the drain on the bottom. Any insight and advice is welcomed, Im just about stumped on this one. Thanks in advance!

Zach
 

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Discussion Starter #2
I was also thinking about adding an inline pump to transfer the fuel with a switch in the cab. Any recommendations on inline pumps that wont flow through when the pump is off?
 

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I have a 46 gallon Aux on my 3500. I did exactly what you are thinking about. Fuel line drops through bed into a Racor Snapp Filter then to Facet fuel pump. I wired the fuel pump to the snow plow light prep switch on the overhead console of my truck. I can now flip the switch going down the road to transfer fuel. I used it on my last trip from WI to MT and it worked perfect. The pump also has a PSO so no fuel unless running and only draws 1.2 amps. Only negatives are the pump is a little noisy and its only rated at 26gph. This actually turns out to be a good thing because its easy to forget its on when on the road.

https://www.pegasusautoracing.com/group.asp?GroupID=FACET

https://www.parker.com/literature/Racor/SNAPP_Presentation.pdf

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Discussion Starter #4
Awesome, thanks for the links. Ill check those out.
 

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Discussion Starter #6
Yeah go for it, Im open to ideas. I was going to just run the cheepo see through wix filters pre and post pump with a Mr Gasket in line pump but I like that Racor filter and it has to last longer than the ones I was going to use. Any idea how many gallons youve had go through yours and have you had to change it out yet?
 

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Discussion Starter #7
As far as the pump wiring and switch, I dont have any unused switches in my 06 so Ill probably just put a switch with an LED in it somewhere in the console so at least when I have it on Ill be able to see the light and not forget to shut it off. Do you have one of the cylindrical pumps or one of the smaller square ones?
 

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The square cube one because it has the pso. The racor had around 750 gallons on the 2 micron and was still going but I just changed it this week to a 30 micron to see if it changed flow rate. Honestly have not seen much difference. The racor are more pricey but better filter with water absorb and super easy to change out with the quick connects they include.
 

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Discussion Starter #10
The little 33003 Wix filter that I have on mine now flows well enough to fill the tank from 1/4 to full in a little over an hour but it depends on how much fuel is in the tank and also how the truck is sitting. I dont want to worry about the flow slowing down on how I park the truck or how much fuel is in the aux tank. So pump it is. Now if I can just figure out why its building so damn much pressure inside the tank. Its a little alarming when you pull the cap off to fill it up and it blows the cap and your hand up into the air and sounds like a blow of valve on a turbo honda. LOL
 

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Some have had a problem where the Aux line goes into the filler neck, it blocked the flow of fuel, because of the inner vent tubing. I realize this is not your problem with building pressure, but something to check.

Good luck
 

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Discussion Starter #16
Some have had a problem where the Aux line goes into the filler neck, it blocked the flow of fuel, because of the inner vent tubing. I realize this is not your problem with building pressure, but something to check.

Good luck
Yeah 06 truck here, no inner vent on mine. The factory filler neck and vent line are separate. Thanks for the insight though
 

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Discussion Starter #17


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Thanks for the picture of your setup. I ordered one of the facet pumps today and probably going to pick up one of those filters in the next few weeks. I have several of the little wix filters laying around so Ill burn through those first then get something better.
 

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Pulled my 5th wheel over the Holiday and had chance to test my new filter set up. Like I suspected the 30 micron flows a bit faster and pump stays quieter. Facet pumps use the fuel to lubricate so makes sense I guess. Next time I change it I will will go with the 15 micron and call it a day. Overall system works great. Transfer fuel on the fly from the cab at a fraction of the cost of the big name systems.
 

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Discussion Starter #19
Very nice! My pump should be here today. I probably wont get around to hooking it up until this weekend though. Not really a big deal, I have to pull the tank back out of my truck anyway and fix a leak on the bottom thats pissing on my bed liner.
 

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Discussion Starter #20
Im going to have to mount my pump and filter a little bit differently than you did Johnson. My 06 doesnt have anything to mount to below the filler neck like yours are. I found a decent spot for the pump, but the Racor filter assembly is going to take some more planning on my truck.
 
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