The fuel system is pressurized. The gas cap is integral part of that pressurization stability. Sorry to say anyone saying it's OK to allow fuel injection to operate unpressurized is incorrect. Replace the cap with a Mazda OEM pressure sensitive cap.

 

Really ??? explain where you ever read that in a technical manual or a source verified author as an ASE or at least Automotive engineering credentials??
The gas cap is part of the emission system. Not having the gas cap is actually more a Federal regulation because it causes air and ground pollution.
In some cases, you can read from DIY sourced information that it will cause you to lose MPG but that is from the fuel evaporating.
On the flip side if a gas cap was so important then there litterly would be vehcles breaking down every day every where and they aren't.
Not having a gas cap itself should not cause anything except a check engine light a DTC(S) and your monitors to be in fault until the cap is replaced wither missing or damaged or not sealing properly.

Cant believe some DIY members on forum for empirical information. Do your research if you want the straight facts and not someone guessing?

READ THIS THREAD:

Car Repair Advice Forum= at your own risk - Mazda Forum - Mazda Enthusiast Forums

 

Last edited by jakasspeech1; Today at 06:54 AM.[/QUOTE]

Just an FYI your original response is in the member history as well any member that sets watch this thread in thier setting will get an alert and the original quote. So editing your response at any time and espcially after this long is sorta of well... I would just say make sure you like what you post and not wait so long to edit if you don't in the future. Also it might be helpful to fill in the reason why you edited it? But I seldom do that.

 

just go to autozone dude

 

Indeed the CE does come on and the gas cap is necessary for a pressurized fuel injection system also the evap fuel vapor emissions are properly operated only when the fuel system maintains constant pressure which the gas cap is a component The days of carburetors & fuel system s operating at atmospheric pressure ie .unpressurized are gone The precisely metered fuel to injection is the function of pressurized closed fuel system is supported only with the pressurized cap. While operating with no cap doing so further allow evaporation emissions into environment so the message is fuel cap crucial component of a pressurized fuel system and emission control component keeping fuel vapor from entering air we all breathe. The pressurized cap is necessary Al this can be confirmed by your dealership That cap does far more than keeping the gas in so keep your Mazda in peak efficiency and replace with what your Mazda was equipped with the environment matters and depends on it

 

[QUOTE=RedIDKthings]Indeed the gas cap is necessary …. [QUOTE]
not all ECU have the programming to alert of missing gas cap. Some will activate a DTC and the I/m monitors will have one or more in fault. However you can run without a gas cap and should not effect the fueling to a degree that you get stranded and the effects will be felt long before any engine damage can occur. Poor starting, idling and MPG reduction. Pleeeeez tell me which PID in any PCM or ECU would effectively change the fueling and how that would damage the engine in short term by not having a gas cap or one that is not sealing properly? Running without a gas cap can release pollutants in the atmosphere that much u got right from you running to the internet for info.
Now on the commonsense side of this response of yours, you're thinking and not understanding the EVAP system would have your audience think that if they forget their gas cap after filling gas which happens so often that short term engine use, they will do cataclysmic engine damage or the engine will shut off leaving you stranded . lol

 

Servicing 2 CX 5 for exact scenario triggered by premature closing of fuel door on both a 2017 naturally aspirated and 2020 GTR service manager concisely explained the fuel injection system fully pressurized & needing to operate pressurized from fuel pump to injectors; the return line keeps closed loop at pressure. The CX5’s are the 9th Mazda’s I’ve owned from a 93 RX7 200MP202010 20202017 frMazda 3 followed the development of every engine & system from mechanical fuel injection in the RX and the transition to electronic in the early 3’s to SkyActive development Real world driving & maintenance across product line. Any editing of posts strong to spelling errors or grammar as if you are owed an explanation

 

First no one like on any forum a grammar ****.

I often post on the fly while working here in the shop.


Your internet found information is lacking the real education and basic level of experience and understanding. But then we have all read some or all of your past responses since you joined!
Let me highlight and try reading it slowly this time?
not all ECU have the programming to alert of missing gas cap. Some will activate a DTC and the I/m monitors will have one or more in fault.
[/QUOTE]
I can see that I should have been a little more explanative in my last response however these 2 phrases above pretty much cover the missing or not fully explaining all aspects of not having a gas cap and a gas cap not fully sealing.
But if any idiot drivers after the warning signs and poor engine performance caused by not having a good sealing gas caps then what can I say!

 

To start this response this thread was started with a question relating to a Mazda 3 . So removed my gas cap for the sake of experimenting I had to go on a parts run at a Toyota dealership that just happen to be 1/2 block down from Mazda. I popped into the service department and a group of us 2 are Mazda factory trained mechanic talked about the no gas cap and Mazda's. While we all agreed that it is better to get the gas cap replaced ASAP none of us in 200+years of service experience never serviced a damaged engine because of not have a gas cap!!! lol Naturally I got the lecture from my friends after showing them this thread and laughing they all said that is an example why we don't go to forums to offer advise and free service help its a waste of time most wont listen and like most DIY and owners like the one arguing with me seem to KNOW-IT-ALL from internet info searching somewhere an answer that supports their thoughts ... LOL
The round trip on my Mazda way 77.6 miles no gas cap no DTC and NO I/M in fault. Hmmm I guess my Mazda must be exceptional or an exception to someone's fact finding mission eh red? rolmao.

 

Oh great arbiter just how many of the vehicles subsystems have to be compromised to cross your threshold of trivial in the case of a missing fuel cap garbage data is generated for tank pressure compromising Fuel delivery monitoring and emissions control systems monitoring gets garbage data why bother monitoring it at all save the money you clearly are master of duct tape shortcut repair advise that multiple errors in 2 subsystems are trivial. Fuel delivery systems and proper emissions control operations seem important to the manufacturer but why bother with it when the decider has decided it doesn’t matter