7.3 Gas Auxiliary Bed Tank Install

[Henris dad]

I am curious about the vent line, is the tank vented? If so how do you not get a check engine light? Is this not the same essentially as having the fuel filler flap cracked open?

 

[Modman]

I am curious about the vent line, is the tank vented? If so how do you not get a check engine light? Is this not the same essentially as having the fuel filler flap cracked open?

The tank has a feed and return line connected to the main tank so it essentially remains closed loop with the OEM system.

 

[J_Man]

My auxiliary tank, manufactured by RDS, is vented.

Laws of physics require a vessel full of fluid have access to air to allow the liquid to be drained… like holding your finger on the end of a straw when you pull it out of your glass… the liquid won’t drain until you release the vacuum.

OEM Tanks also must be vented - I believe this is accomplished via the fuel vapor canister system which is one element of the emissions control systems. (Conjecture on my part - I have no definitive source of truth for this but I’m holding that opinion until someone corrects my error ).

Here is the question: Once you connect Aux Tank-2 (even if unvented) to OEM Tank-1 (vented) are not both tanks now effectively vented?

I’m testing this theory now.

I installed a check valve on the output of my pump yesterday - and left the overflow return line ‘un-checked’ — I’ll know after I drive a while if I get an error code and need a 2nd check valve on the fuel return (over-flow) line.

Here is a link to the ATI (Tanks Inc) position on venting of tanks: https://www.tanksinc.com/index.cfm/page/ptype=results/category_id=160/mode=cat/cat160.htm#:~:text=Your tank has to breathe,relieve both vacuum and pressure.

J_Man

 

[Modman]

OEM Tanks also must be vented

Correct, although not directly to atmosphere. The ATI system retains that OEM aspect which is why it maintains legality.

 

[J_Man]

7.3-L F250 KR Aux Tank — Need help / advice

— I just installed the ATI 2-port filler neck adaptor and the dreaded check engine light came on after about 25-miles.

The error text shows an emission issue, and suggests checking the filler cap to make sure it is tight.

J_Man

UPDATE - error code issue is resolved (or appears to be resolved).

I installed an Evil Energy check valve (the expensive version compatible with methanol fuel additives) just after the output port on the Carter fuel pump and have had ZERO error codes in over 500-miles, towing, not-towing, local and longer-distance runs.

I think the only condition I have not tested is having the aux tank totally empty, which I don’t expect to happen in use.

My aux tank is rated at 48-gallons but max fill is ~35 gal so my total on-board fuel is ~70-gallons - enough for my needs.

I have a few photos snd cost details if anyone needs them, drop me a message.


J_Man

 

[Modman]

UPDATE - error code issue is resolved (or appears to be resolved).

I installed an Evil Energy check valve (the expensive version compatible with methanol fuel additives) just after the output port on the Carter fuel pump and have had ZERO error codes in over 500-miles, towing, not-towing, local and longer-distance runs.

I think the only condition I have not tested is having the aux tank totally empty, which I don’t expect to happen in use.

My aux tank is rated at 48-gallons but max fill is ~35 gal so my total on-board fuel is ~70-gallons - enough for my needs.

I have a few photos snd cost details if anyone needs them, drop me a message.


J_Man

Glad that you were able to resolve it!

 

[Henris dad]

Is anyone having any issues with CEL while driving and transferring fuel, (AI thinks I may get errors from the truck seeing the fuel level rise while in motion)? I have the Carter pump and fittings and about to start on my F150. thx to all for the thread and input, looking forward to an additional 22 gallons in my truck.

 

[Modman]

Is anyone having any issues with CEL while driving and transferring fuel, (AI thinks I may get errors from the truck seeing the fuel level rise while in motion)? I have the Carter pump and fittings and about to start on my F150. thx to all for the thread and input, looking forward to an additional 22 gallons in my truck.

No CEL on a '22 SD. The only issue is that it doesn't register on the gauge and DTE for some time constant. Seems to be about 30min., possibly tied to the fuel economy history cycle?

 

[Henris dad]

Thx

 

[J_Man]

My approach so far (my direct-feed system has been functional for 4 to 6 weeks, so not long) has been to transfer fuel when we stop for food or bathroom breaks. I'm certain that topping off the OEM tank while driving is 100% functional - but I'm guessing it would really confuse the DTE calc which I like to keep track of...


J_Man

 

[Henris dad]

Thx, I would take that approach for sure, but would like to transfer fuel while driving when out west as well.