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2021 cx-30 2.5l AWD Turbo premium package
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Discussion Starter · #1 ·
I've had the beast long enough to get in a couple of fill ups.

I'm having issues with what appears to be a premature shut off at the pump, leaving me with less than a full tank. I estimate it's a half gallon / gallon short each time.

I'm hesitant to override the shut off mechanism, and risk an overflow.

Any tips to be had out there?

p.s. Went on a quick road trip, put on about 150 miles, all country roads, lot's of hills and curves. What an experience, especially when compared to driving my old Rav4 on those same roads. Reasonably good gas mileage, coming in around 26mpg, roundtrip.
 

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2021 CX-30 S 2.5L white/black
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In a properly functioning gas pump the cutoff will cut off multiple times. I always go one more time after it first cuts off until it cuts off again and mostly go two times. It adds another 0.5-1 gallon of fuel and has never spilt a drop. YMMV
 

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Discussion Starter · #3 ·
In a properly functioning gas pump the cutoff will cut off multiple times. I always go one more time after it first cuts off until it cuts off again and mostly go two times. It adds another 0.5-1 gallon of fuel and has never spilt a drop. YMMV
I'm used to he sound of the filler neck on my Rav4, and the cx-30 is so quiet, I couldn't tell if I was close to the limit when I did try to force the pump.

I'll try a double pump the next time...
 

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2021 CX-30 S 2.5L white/black
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I'm used to he sound of the filler neck on my Rav4, and the cx-30 is so quiet, I couldn't tell if I was close to the limit when I did try to force the pump.

I'll try a double pump the next time...
Let me clarify that is all based on the last 3 dozen plus cars owned. I just got the CX-30 and other than about 1 gallon on the way home to start the fuelly.com counter running I haven't filled it. I anticipate it being the same but haven't proven it in actual usage yet.
 

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Discussion Starter · #5 ·
Let me clarify that is all based on the last 3 dozen plus cars owned. I just got the CX-30 and other than about 1 gallon on the way home to start the fuelly.com counter running I haven't filled it. I anticipate it being the same but haven't proven it in actual usage yet.
Thanks for the clarification...
 

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Modern cars are designed to shut off before the tank is totally full to avoid damaging the evap system, the pressure can damage the charcoal filter.
 

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Discussion Starter · #8 ·
One backseat Mechanic posting here: If you have a problem with your _, try this!" Scotty: "If you do _ to your car, you're stupid!" lmao
Ah Scotty. He's on my subscribed list, but I missed this gem. Obviously, it makes some sense...

The question is: why would car makers set up a design that keeps the car from receiving a full tank...BY DESIGN?

Additionally, I was grudgingly OK with a smaller fuel tank to start with. Now, in order to save the evaporator, I have to forgo another 1/2 -1 gallon on a fill up. Kinda grinds my gears, if you catch my drift!
 

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It's a mandated emissions thing, it stops gas fumes escaping. I'm not sure it really matters if the tank is 100% full, what matters to me is the capacity of the tank I can actually use.

That said, this car has an absolutely tiny gas tank. I do miss the 72 liter tank my last car had.
 

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Discussion Starter · #10 ·
It's a mandated emissions thing, it stops gas fumes escaping. I'm not sure it really matters if the tank is 100% full, what matters to me is the capacity of the tank I can actually use.

That said, this car has an absolutely tiny gas tank. I do miss the 72 liter tank my last car had.
As I've gotten older, my ability to sit/drive for more than 3-4 hours at a stretch without a break is non existent. So that equates to range of this gas tank. Might be a blessing in disguise, we'll see.
 

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'21 CX-30 2.5 Sky G Pref AWD Red
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Stated capacity is 12.7gal for AWD (13.5 for FWD) If I run till low fuel warning, I typically get around 10.5gal in at the auto shutoff. With it showing 20-30 miles left till empty that's roughly another gallon. If they allow another gallon beyond that for people who don't pay attention to the unmissable warning, that would account for the full capacity.
 

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2020 CX-30 GT - Skyactive G - 2.5 L AWD
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I am still old school and like to see my tank being full. I know it is not recommended but it is just something I need to do, so all my vehicles I always fill them to max.
 

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2020 Mazda 3 Premium Hatch polymetal gray over red/blk
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Ah Scotty. He's on my subscribed list, but I missed this gem. Obviously, it makes some sense...

The question is: why would car makers set up a design that keeps the car from receiving a full tank...BY DESIGN?

Additionally, I was grudgingly OK with a smaller fuel tank to start with. Now, in order to save the evaporator, I have to forgo another 1/2 -1 gallon on a fill up. Kinda grinds my gears, if you catch my drift!
Scotty is not alone on this. Why topping off your gas tank is a bad idea
It has been the advise from manufacturers and auto experts at least since the widespread use of evaporative emissions equipment was required, 2 decades +?.

My first gen CX5 would go 70 miles past empty. If I filled up at empty, I already had over 2 gals in the tank. If squeezing every mile out of a tank is so important to you, I would suggest running the car to a sputtering stop ,with a can on board of course, so you can see the actual limit rather than relying on fuel warnings from the car which in Mazda's case are frequently very pessimistic
 

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'21 CX-30 2.5 Sky G Pref AWD Red
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evaporative emissions equipment was required, 2 decades +?.
More like 5 decades. My 75 Plymouth Duster has an evap canister.
 

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Discussion Starter · #15 ·
Scotty is not alone on this. Why topping off your gas tank is a bad idea
It has been the advise from manufacturers and auto experts at least since the widespread use of evaporative emissions equipment was required, 2 decades +?.

My first gen CX5 would go 70 miles past empty. If I filled up at empty, I already had over 2 gals in the tank. If squeezing every mile out of a tank is so important to you, I would suggest running the car to a sputtering stop ,with a can on board of course, so you can see the actual limit rather than relying on fuel warnings from the car which in Mazda's case are frequently very pessimistic
My issue with the inability to get a "full tank" at fill up is more about my OCD.

I like to see a full tank after the auto shut off kicks in, not drive away from the pump and see I'm a few hashes short of full.

It's an OCD thing, and not a real world problem.
 

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'21 CX-30 2.5 Sky G Pref AWD Red
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My issue with the inability to get a "full tank" at fill up is more about my OCD.

I like to see a full tank after the auto shut off kicks in, not drive away from the pump and see I'm a few hashes short of full.

It's an OCD thing, and not a real world problem.
Hmm, that’s a different problem. I’m pretty sure my gauge reads full.
 

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Discussion Starter · #17 ·
Hmm, that’s a different problem. I’m pretty sure my gauge reads full.
As I re-read my OP, I see I failed to include the OCD / Gauge issue.

Can't ask for assistance without providing full details...sorry about that!
 

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2021 CX-30 S 2.5L white/black
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Mine always reads full no matter which way I do it. It's just a question of how quickly it begins to drop from full. Pretty quickly if I don't top off, not so soon if I do. I don't think I've ever had a car that didn't read full at the first cutoff.
 

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Discussion Starter · #19 ·
Mine always reads full no matter which way I do it. It's just a question of how quickly it begins to drop from full. Pretty quickly if I don't top off, not so soon if I do. I don't think I've ever had a car that didn't read full at the first cutoff.
I've never had this top off issue with my other cars. And though I've always hit the pump on more time after shutoff, there have never been any mechanical problems due to "overfilling".

But with this beast, both "fill-ups" stopped well short of reading a full tank. On the second fill-up, I tried to goose the pump one time but the sounds I was hearing led me to believe that I was close to the filler neck, so I didn't press this issue.

Again, not a life altering issue, just a curiosity...
 

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'21 CX-30 2.5 Sky G Pref AWD Red
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I've never had this top off issue with my other cars. And though I've always hit the pump on more time after shutoff, there have never been any mechanical problems due to "overfilling".

But with this beast, both "fill-ups" stopped well short of reading a full tank. On the second fill-up, I tried to goose the pump one time but the sounds I was hearing led me to believe that I was close to the filler neck, so I didn't press this issue.

Again, not a life altering issue, just a curiosity...
How much can you put in to fill from an empty tank?
 
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