Is it Ok to keep the rex gas tank empty?

[Ronmamaci3]

Haven't used gas tank for a whiles and it's bed empty. Will it cause any issues?

 

[SSi3]

naw, its never actually completely empty anyways. The system keeps some fuel in the bottom (maybe half a litre?) so the lines aren't sucked dry by the engine, which would make it harder to start when its needed. If you're in a winter climate it's a good habit to keep it full or nearly full to minimize condensation in the tank (and offset the shorter cold weather battery range, don't want to be stuck on the side of the road in the winter).

 

[jadnashuanh]

WIth the closed system and pressurization, there won't be much evaporation, but keep in mind, depending on where you live, there could be a moderate amount of ethanol in the gasoline. Any moisture that might be there will tend to be absorbed by the ethanol, since there's not much, the effect will end up worse. Old, ethanol gasoline mixes tend to gel if there's any moisture issue longer term...something that does not promote reliability.

Personally, I'd keep it full and don't let it sit more than about 3-months before refilling. I didn't see the need for the REx for my use pattern, so avoided it which means less to worry about.

 

[viking79]

I think Ethanol only gels if it is mixed with MTBE or some other agent not present in the ethanol fuel you buy at the pump. Ethanol should have no trouble storing 6 mo to a year in the pressurized tank of the i3.

MTBE hasn't been used in gasoline since 2005 or 2006.

 

[jadnashuanh]

Alcohols have a great affinity for moisture. Once they exceed their capacity to absorb it, then you have problems. There are a couple of threads here where people have had problems with their REx where, through extended storage, the fuel turned to gell and the vehicle wouldn't run. One person I trust runs a small engine repair facility...one of his biggest jobs is cleaning out fuel systems from old fuel that contained ethanol. Most of those do not have the same sealed, pressurized systems, but why risk it? Also, the octane (highly volatile components) tend to evaporate over time, lowering the octane level. Again, the sealed, pressurized system should help, but where does that extra air to pressurize the system come from...outside, where the air does contain some moisture. Avoid all of those potential problems by using the fuel once in awhile and refill with fresh. The more full, less air needed to pressurize the tank, longer life.

 

[Tacfoto]

Conventional wisdom back in the bad old days of ICE was if you are going to not use the car, park it full of gas. Less air in the tank to expand and contract, and a large amount of fuel to dilute any water, etc that makes it's way in. I parked a VW Rabbit in a storage unit with a trickle charger and a full tank for 18 months and it started on the first key turn and ran like a champ thereafter.

I do think i3 REx drivers get a little carried away in the "I haven't used gas in 2 months" - "Well ha ha you suck because I haven't used gas in 3 months!" thing. I use my REx all the time because every 2-3 weeks I drive someplace a few hundred miles away or more. And if you don't you could just not charge for a week or 2 until the REx ran through a tank, or code and use the hold option.

 

[theothertom]

It's not a good idea to keep it empty because the REx goes through a maintenance cycle at periodic intervals. There has to be gas in the tank to do this.

 

[sipabit]

+1