Slight hesitation after filling 'er up - Toyota GR86, 86, FR-S and Subaru BRZ Forum & Owners Community

stranger things · 05-20-2017, 09:55 PM

I've had my FR-S for a few weeks now and noticed something strange. After I fill up the gas, start it up, and attempt to leave the station, the car hesitates at first and almost wants to stall. I have to let out the clutch slow and easy to prevent it from stalling. But after driving around for a while, it's back to normal.

Any ideas on what might cause this? The car is stock except for K&N drop-in filter. I only use Mobil 93. I have no idea what the previous owner used, or for that matter, what the dealership filled it up with when I took delivery.

Thanks.

Tcoat · 05-20-2017, 11:51 PM

Never noticed this before. The fuel system is a pressurized continuous loop. Perhaps for some reason yours just takes a minute to pressurize again. Doesn't matter what fuel the dealer used since that would be long gone.

alan.chalkley · 05-21-2017, 12:06 AM

It does the same if you stop for a short time at the shops.
All of my cars both past and present have done this.
I guestimate it has something to do with auto choke quickly stopping and uneven temp throughout the engine.
Because when the engine is turned off , heat rises and heats up the fuel rails and inlet manifold.
This was a big problem with my old ford falcon , the rising heat would overheat the starter motor and the solution of fixing sheet metal under the started motor was "official" , but did not work.
It is very noticeable on hot 40+ degrees C days

guybo · 05-21-2017, 07:43 AM

Evap system. If the car has been topped off too many times (even once it too many time IMHO), the evap system charcoal cannister gets clogged up and the evap system will cause probs with hard starting and maybe rough idle. If you get a CEL P0442 then that's what it is. It could be in the rough start only stage and not cause a CEL yet, but keep an eye on it.

That said, there are a million things that can cause a rough start, this is only one suggestion.

humfrz · 05-21-2017, 05:49 PM

As a follow up ^ ...... when you fill it up, do you just add gas till the pump clicks off the first time ....... or do you try to get a little more in the tank ..... ??

humfrz

stranger things · 05-21-2017, 08:09 PM

Thanks for the feedback, guys. Not too worried since it lasts a few seconds and goes back to normal.

To answer humfrz's question, I only fill up till it clicks off. I never try to fill up beyond that.

05-20-2017, 09:55 PM	#1
stranger things The Upside Down Join Date: Apr 2017 Drives: '13 FR-S Location: Hawkins Laboratory Posts: 117 Thanks: 176 Thanked 69 Times in 45 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Slight hesitation after filling 'er up I've had my FR-S for a few weeks now and noticed something strange. After I fill up the gas, start it up, and attempt to leave the station, the car hesitates at first and almost wants to stall. I have to let out the clutch slow and easy to prevent it from stalling. But after driving around for a while, it's back to normal. Any ideas on what might cause this? The car is stock except for K&N drop-in filter. I only use Mobil 93. I have no idea what the previous owner used, or for that matter, what the dealership filled it up with when I took delivery. Thanks.

05-20-2017, 11:51 PM	#2
Tcoat Senior Member Join Date: Jul 2014 Drives: 2020 Hakone Location: London, Ont Posts: 69,845 Thanks: 61,656 Thanked 108,284 Times in 46,456 Posts Mentioned: 2495 Post(s) Tagged: 50 Thread(s)	Never noticed this before. The fuel system is a pressurized continuous loop. Perhaps for some reason yours just takes a minute to pressurize again. Doesn't matter what fuel the dealer used since that would be long gone. __________________ Racecar spelled backwards is Racecar, because Racecar.

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05-21-2017, 12:06 AM	#3
alan.chalkley Senior Member Join Date: Feb 2012 Drives: 4wd zooks Location: Sydney / Australia Posts: 495 Thanks: 135 Thanked 167 Times in 108 Posts Mentioned: 1 Post(s) Tagged: 0 Thread(s)	It does the same if you stop for a short time at the shops. All of my cars both past and present have done this. I guestimate it has something to do with auto choke quickly stopping and uneven temp throughout the engine. Because when the engine is turned off , heat rises and heats up the fuel rails and inlet manifold. This was a big problem with my old ford falcon , the rising heat would overheat the starter motor and the solution of fixing sheet metal under the started motor was "official" , but did not work. It is very noticeable on hot 40+ degrees C days

05-21-2017, 07:43 AM	#4
guybo Huge E85 fan! Join Date: May 2016 Drives: 2016 Scion FRS Location: Tampa, FL, USA Posts: 1,850 Thanks: 539 Thanked 1,010 Times in 605 Posts Mentioned: 32 Post(s) Tagged: 0 Thread(s)	Evap system. If the car has been topped off too many times (even once it too many time IMHO), the evap system charcoal cannister gets clogged up and the evap system will cause probs with hard starting and maybe rough idle. If you get a CEL P0442 then that's what it is. It could be in the rough start only stage and not cause a CEL yet, but keep an eye on it. That said, there are a million things that can cause a rough start, this is only one suggestion.

05-21-2017, 05:49 PM	#5
humfrz Senior Member Join Date: May 2013 Drives: 2013 FR-S, white, MT Location: Puyallup, WA Posts: 29,872 Thanks: 28,793 Thanked 31,826 Times in 16,429 Posts Mentioned: 708 Post(s) Tagged: 2 Thread(s)	As a follow up ^ ...... when you fill it up, do you just add gas till the pump clicks off the first time ....... or do you try to get a little more in the tank ..... ?? humfrz

05-21-2017, 08:09 PM	#6
stranger things The Upside Down Join Date: Apr 2017 Drives: '13 FR-S Location: Hawkins Laboratory Posts: 117 Thanks: 176 Thanked 69 Times in 45 Posts Mentioned: 0 Post(s) Tagged: 0 Thread(s)	Thanks for the feedback, guys. Not too worried since it lasts a few seconds and goes back to normal. To answer humfrz's question, I only fill up till it clicks off. I never try to fill up beyond that.

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