LRA Controller sorcery.

[grinchy]

Wait wait wait. What does the LRA do when the main is ‘overfilled’? Where does the fuel go or where is it supposed to go?

 

[Artie]

it’s interesting that some folks report they either can’t fill their LRA to capacity or can’t get all of the gas out of it and others don’t have issues. I have a 24 gal LRA and can get all but the last 1/2 gal out. I usually hit the transfer button once after it auto shuts off. I think it runs one minute and shuts off again.

I’ve measured the flow rate and mine (upgraded pump) flows at 1 gpm. On road trips I let the main tank run down to 1/4 and then start the transfer and a timer set for 12 minutes. I shut the pump off when they timer beeps. There is lag in the fuel gauge but after a few minutes more, my gauge will read 3/4 and I know I have 12 gal in the LRA.

Autofill sounds cool but one of my fears is inadvertently overfilling the main tank and I’d be worried about a controller failure or the lag in the gauge reading affecting the reliability. I like my watch telling me to shut the pump off and knowing I have 1/4 tank head room for any error.

This is pretty much my procedure, 15 min and shut it off. I should set a timer because I have forgotten a couple times but nothing has ever come of it, I’ve maybe gone 20 minutes.

 

[CanadianRockyCruiser]

Wait wait wait. What does the LRA do when the main is ‘overfilled’? Where does the fuel go or where is it supposed to go?

If I am interpretting this correctly, It overflows, just like if you overfilled with a jerrycan. Presumably, it would frood the charcoal canister first, and potentially backfill the vent into the secondary tank via the filler neck.

That is why a feedback mechanism from the main tank would be desirable (sender wire).

 

[Artie]

View attachment 3977288
If I am interpretting this correctly, It overflows, just like if you overfilled with a jerrycan. Presumably, it would frood the charcoal canister first, and potentially backfill the vent into the secondary tank via the filler neck.

That is why a feedback mechanism from the main tank would be desirable (sender wire).

But isn’t the vent line to the filler neck the first place it can overflow into?

 

[kcjaz]

But isn’t the vent line to the filler neck the first place it can overflow into?

The two tanks are connected at the dual filler neck. If the main tank overfills it will back up to the gas cap and go back to the aux tank. Flow circuit wise it would be fine and effectively be in recirc mode. The issue would be flooding the charcoal canister