Ronmamaci3
Posts: 17
Joined: Wed Mar 21, 2018 5:00 pm

Is it Ok to keep the rex gas tank empty?

Wed Jul 18, 2018 5:57 pm

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

SSi3
Posts: 254
Joined: Mon Sep 15, 2014 7:55 am
Location: Ontario, Canada

Re: Is it Ok to keep the rex gas tank empty?

Thu Jul 19, 2018 9:28 am

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).
Born electric 4/25/15 (2015 REx)
Re-born fully electric 7/27/19 (2019 i3s BEV)

jadnashuanh
Posts: 5154
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Is it Ok to keep the rex gas tank empty?

Thu Jul 19, 2018 3:53 pm

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.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

viking79
Posts: 110
Joined: Wed Apr 16, 2014 3:04 pm

Re: Is it Ok to keep the rex gas tank empty?

Thu Jul 19, 2018 4:06 pm

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
Posts: 5154
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Is it Ok to keep the rex gas tank empty?

Thu Jul 19, 2018 7:07 pm

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.
Jim DeBruycker
2014 i3 BEV, 2021 X5 45e
(The i3 will be sold soon, <17K-miles, interested?)

Tacfoto
Posts: 56
Joined: Sun Mar 11, 2018 11:48 pm

Re: Is it Ok to keep the rex gas tank empty?

Thu Jul 19, 2018 8:37 pm

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
Posts: 364
Joined: Mon Mar 20, 2017 6:08 am
Location: South Carolina

Re: Is it Ok to keep the rex gas tank empty?

Fri Jul 20, 2018 5:26 am

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
Posts: 192
Joined: Sun Mar 04, 2018 2:01 am
Contact: YouTube

Re: Is it Ok to keep the rex gas tank empty?

Sat Jul 28, 2018 12:06 am

+1
A fanatic of all things electric. Ridables like electric ice chests and stand up scooters I adore. Drones like DJI, I root for. I'm a fan of both, but nothing beats my love for my 2016 i3 Rex with Deka World. Shhh, don't tell my wife.

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