My brother and I have both witnessed the mini acting weird when filling up gas in it. It starts to idle very very rough. Before pumping gas it would stand around 800-900 rpm than when its pumping in it starts to drop to like 300-500 rpm. I tried to rev it up to keep the car alive but it was not able to rev up. I ended up just shutting the car off. After I was done filling up I tried starting it and it just did not start. It took a good 2 seconds of just cranking and nothing happened. After the 2nd or 3rd try it finally started. Nothing seemed weird after.
Let me know
Thanks

 

First, why are you fueling with the engine running?

Second, does it act weird if you do the intelligent thing and shut the car off before you start pumping gas?

 

I always fuel with the engine on I never had any issues with it. And I do not understand your second question. What do you mean intelligent thing?

 

To be honest, I don't know how to rephrase that question to make it clearer.

 

​​The point is, fueling with the car running can cause changes with the EVAP system (including pointing out small vacuum leaks) and give false readings to the ECU, and it may simply be trying to adapt to those changes.
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​​​​​The other question is, do you get the same result when idling and not opening the gas cap, or does it stutter when you restart after fueling without the car running.

 

Thanks for clarifying my train of thought @BlwnAway. My brain doesn't seem to be all here this morning. Or maybe that's just normal...

 

I have never had the car idle with the gas cap off.

 

But then... how do you know the idle drops when you're filling it?

 

Oh I see what you mean. The answer is neither. I do not get the same result when idling and not opening the gas cap and it has never stuttered when I restart after fueling without the car running. Sorry I did not understand what you were asking.

 

Drive the car for 20 minutes.
put the car in park.
Sit still for 5-8 minutes like you are gassing it up.

Does it idle rough?

If not, it is deffinatley a response to running the car woth the gas cap off, which it is designed to not do for modern emissions standards.

Does this provide more clarity?

Happy to help!

 

During normal operation, the fuel system is pressurized. Loosen the gas cap and the pressure drops off and the engine doesn't function as normal. That is SOP. Ya gotta take the cap off to refuel so then what happens? For every action, there is an equal and opposite reaction. And as an aside, really bad things have happen when automobiles have been abandoned with the engine left running.

 

I was actually trying to rationalize this one earlier. It's obviously a massive evap leak at the tank, but I wouldn't think fuel tank pressure would affect fuel delivery by the pump (or am I missing something?) Presumably the vacuum leak from the purge valve opening and dumping extra air into the throttle body is the issue? The car should be throwing a code for that I would think.

I've never run a modern vehicle with an evap system without the cap on for obvious reasons, so I'm a bit curious as to the exact cause. My '67 will run happily without a gas cap, but it has zero emissions controls and a cap that's vented straight to atmosphere.

 

My guess would be a clogged evap could cause it or a vacuum leak somewhere. I'd start by STOP FUELING UP with the car running ( causes list of issues ) and then check into those 2x things. I could be wrong but I swear filling up certain cars while running will ruin evap and purge related components or cause excess wear on them causing them to fail sooner .

 

This is fake, right? Someone tell me this is fake.

 

The ECU adapts to vacuum leaks pretty well (hence all the "unknown rough idle with no code threads) it has to be pretty major to throw a code.
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Lest we forget, static electricity could possibly solve the problem when refueling with the engine running....provided there is sufficient insurance coverage.

 

Genuinely curious as to your reasoning for leaving the engine running while fueling.

 

Vaguely related: - some of the larger Fords/Mercuries will stall if the gas cap is removed with the engine running.
It is also very easy to flood the evap system if you try to top off the tank too much.

 

I guess that makes sense, and knowing that it doesn't always throw codes for that kind of thing will be useful in the future. I've never had to deal with these sorts of things on my R50, and my other vehicles are all pre-OBD. Heck, my van only has one vacuum line, and it's just the one for the vacuum advance on the distributor.

 

"Hey Doc!, it hurts when I poke myself in the eye with my finger."
Doc: "dont poke yourself in the eye".

 

I hope it is...

First of all... The gas station clearly doesn't care if they let people refuel with their engine running... It's a big no for obvious fire hazard reasons. I hate when diesel owners leave their vehicle running next to me when I'm refueling... sure your diesel won't ignite, but the fumes from mine can...

Secondly, the fuel tank is a closed system, it's been that way since evap was born to stop venting fuel vapors to the atmosphere. When you refuel, you're creating a lot of those from the fuel rushing into the tank. If for some reason the vsv up front is open when refueling, it's sucking up fumes from the canister and running too rich. It's also a terrible idea to keep forcing fuel in when the trigger released from the pressure as you're pushing fuel up that can then crawl in the hole at the top of the filler hose and then enter the evap system and it's not meant to have liquid fuel in there.

But... DO NOT let your vehicle run when refueling, ever... Even diesel ones have no justification in doing so, if the engine started and you drove to the fuel station, it's warm enough that it will restart without issues.

 

Hi all,
I have read all your posts about my issue and I appreciate your response. I can clearly make out that it is wrong to leave the car on when filling up gas due to pressure and evap system getting messed up and stuff. I am 16 and this is my first car so I only know so much about the basic rules of a car and what you should and should not do with it.

Zagnutbar: I will try that out and let you know what happens. Thank you.

MiniManAdam: I recently had a check engine light for a leak in my evap system which was found near my gas cap. I got it fixed so currently the car stands with no evap leaks.

chrunck: Wish it was my friend.

 

Well, good on you for asking questions! I was young and dumb once, I can relate. Now I'm old and still mostly dumb

 

I remember your new forum member intro post 2+ months ago and marveled then (and now) at your clarity of writing not common at your age. Keep that up and Motor On!

 

Cmon guys why all the flame ????? That's not the norm of this community here ,let's not give this newcomer a bad welcome...
welcome buddy !!!!! Don't EVER be afraid to ask questions. It's stupid when people don't ask and just assume they know everything... THATS stupid...
your evap leak may be fixed but you may have issue with the purge valve IF these cars have that but it's pretty easy to rig up a smoke tester to use on these cars to check for vacuum leaks.. need a swishersweet cigar and a 10$ fluid transfer handpump from an autoparts store... if you want more info I can post a link showing the process..