High Idle After Fueling - Focus Fanatics
Ford Focus Forum
HomeContact UsAbout UsGalleryDiscussion ForumsMarketplace


Go Back   Focus Fanatics > Ford Focus Tech Discussions > General Technical Chat

General Technical Chat This section is for technical discussions relating to general maintenance, electrical issues, engine trouble, and recalls.

Search This Forum | Image Search | Advanced Search    
Ford Focus Tire & Wheels FocusFanatics Merchandise

Reply
 
Thread Tools Display Modes
Old 09-18-2013, 11:47 AM   #1
MTB79
Focus Jr. Enthusiast
 
Join Date: May 2013
Fan#: 114244
Posts: 41
FF Reputation: 1 MTB79 Good Standing Member
Buy-Sell-Trade Rating: (0)
High Idle After Fueling

I have a 2000 MK1 1.6 Zetec, and something strange is happening. After I refuel my rev's then sit around 3k and takes about 5 seconds before it drops to about 1.5k and sits there, its also pinging as well when pulling off in first gear during this time. After a few days it returns to normal.

Something to note is that every time I undo the fuel cap there is a rush of air, not sure if its in or out though.

Has anyone come across this or have any ideas what could be causing it?

Thanks!


MTB79 is offline  
    Reply With Quote
Sponsored Links
Advertisement
 
Old 09-18-2013, 04:43 PM   #2
MTB79
Focus Jr. Enthusiast
 
Join Date: May 2013
Fan#: 114244
Posts: 41
FF Reputation: 1 MTB79 Good Standing Member
Buy-Sell-Trade Rating: (0)
I thought it could be a fuel tank breather hose but then i thought it would be better when the cap had been removed as the pressure would be normalised and get worse over time rather than the other way around?
MTB79 is offline  
    Reply With Quote
Old 09-18-2013, 06:04 PM   #3
spiller
Focus Enthusiast
 
spiller's Avatar
 
Join Date: Jun 2010
Fan#: 75607
Location: Memphis, TN
What I Drive: 11 Sangria SE sed, 01 Wht SE Wagon

Posts: 154
FF Reputation: 1 spiller Good Standing Member
Buy-Sell-Trade Rating: (0)
It could be the gas cap vent. The cap is to allow air into the tank and keep fuel vapors from escaping. When full, a small decrease in the fuel volume in the tank will lead to large megative pressure. The cap is still venting (barely) or pressure is balanced in the EVAP cycle.
Because fuel is regulated so precisely for combustion, that negative pressure may be reducing the volume/pressure to the injectors setting up a lean-burn detonation.
(That's just my dart at your strange symptoms)
spiller is offline  
    Reply With Quote
Old 09-18-2013, 06:20 PM   #4
jims shadetree
Focus Addict
 
jims shadetree's Avatar
 
Join Date: Jun 2013
Fan#: 116036
Location: devils elbow, MO
What I Drive: 2013 tuxedo black 5 spd hatch se

Posts: 1,060
FF Reputation: 1 jims shadetree Good Standing Member
Buy-Sell-Trade Rating: (0)
Are u stoppin filling when pump shuts off or do u keep shoving fuel in ?
__________________
Hatch nation #66
Gettin my kicks on route 66!
jims shadetree is offline  
    Reply With Quote
Old 09-19-2013, 12:55 AM   #5
MTB79
Focus Jr. Enthusiast
 
Join Date: May 2013
Fan#: 114244
Posts: 41
FF Reputation: 1 MTB79 Good Standing Member
Buy-Sell-Trade Rating: (0)
Quote:
Originally Posted by spiller View Post
It could be the gas cap vent. The cap is to allow air into the tank and keep fuel vapors from escaping. When full, a small decrease in the fuel volume in the tank will lead to large megative pressure. The cap is still venting (barely) or pressure is balanced in the EVAP cycle.
Because fuel is regulated so precisely for combustion, that negative pressure may be reducing the volume/pressure to the injectors setting up a lean-burn detonation.
(That's just my dart at your strange symptoms)
Would a first step be to replace the gas cap in this case?





Quote:
Originally Posted by jims shadetree View Post
Are u stoppin filling when pump shuts off or do u keep shoving fuel in ?
I only ever fill to about half so it doesn't shut off at all.
MTB79 is offline  
    Reply With Quote
Old 09-19-2013, 09:31 AM   #6
spiller
Focus Enthusiast
 
spiller's Avatar
 
Join Date: Jun 2010
Fan#: 75607
Location: Memphis, TN
What I Drive: 11 Sangria SE sed, 01 Wht SE Wagon

Posts: 154
FF Reputation: 1 spiller Good Standing Member
Buy-Sell-Trade Rating: (0)
Quote:
Originally Posted by MTB79 View Post
Would a first step be to replace the gas cap in this case?
I only ever fill to about half so it doesn't shut off at all.
Then not likely, but the little things are still nice to eliminate. My scenario required a fill-till-FULL.
The only other thing that strikes me is an EVAP/Purge control valve issue or line leak between Purge Control Valve and intake. A MIL/CheckEngine may not be lighting for lack of consistent failure or your driving habits prevent the EVAP test by OBDII to run test.
Check the EVAP hoses for deteriation, especiall between purge control valave and intake. A bad Purge Valve should cause a CheckEngine, but a bad hose after the valve may not. (But why would it settle down later...?)

(EDIT) Wait, that's not right either. EVAP should be bled to air-box before throttle body...

Last edited by spiller; 09-19-2013 at 09:41 AM. Reason: Changed mind on validity of answer
spiller is offline  
    Reply With Quote
Old 09-19-2013, 10:35 AM   #7
MTB79
Focus Jr. Enthusiast
 
Join Date: May 2013
Fan#: 114244
Posts: 41
FF Reputation: 1 MTB79 Good Standing Member
Buy-Sell-Trade Rating: (0)
Would checking EVAP hoses require dropping the tank?
MTB79 is offline  
    Reply With Quote
Old 09-19-2013, 03:01 PM   #8
spiller
Focus Enthusiast
 
spiller's Avatar
 
Join Date: Jun 2010
Fan#: 75607
Location: Memphis, TN
What I Drive: 11 Sangria SE sed, 01 Wht SE Wagon

Posts: 154
FF Reputation: 1 spiller Good Standing Member
Buy-Sell-Trade Rating: (0)
No. The EVAP hoses in the engine bay. A failure of any EVAP hoses before the Purge valve should cause a code.
Go ahead and replace the fuel cap. Its really the only thing that changes that should matter after you add fuel.
Most anything I can think of that could increase the rev/idle speed wouldn't be allayed over driving after fill-up....
When you fill up, do you keep the radio playing? Are the keys in the Run position?
spiller is offline  
    Reply With Quote
Old 09-19-2013, 03:07 PM   #9
whynotthinkwhynot
Captain TMI
 
whynotthinkwhynot's Avatar
 
Join Date: Jan 2005
Fan#: 18416
Location: the armpit of TN, Memphis, TN
What I Drive: 05 ZXW; 02 Windstar; 13 C-Max SEL

Posts: 20,126
FF Reputation: 270 whynotthinkwhynot Outstanding Standing Member whynotthinkwhynot Outstanding Standing Member whynotthinkwhynot Outstanding Standing Member
Buy-Sell-Trade Rating: (1)
You might want to research how "Evaporative Emissions" systems work to vent the fuel tank. That will be helpful in your diagnostics and understanding what the parts of the system are and what they do. You could have a clogged system, kinked system, or bad purge valve. Start with the cheapest repair first if you're guessing!
__________________
Be eclectic.
---The Complete How-To Archive--

Moderating everything now, let me know if I can help.

Quote:
Originally Posted by the user formerly known as ZX3_Chick View Post
You're special aren't you.
whynotthinkwhynot is offline  
    Reply With Quote
Old 09-19-2013, 10:24 PM   #10
Leora83
Focus Enthusiast
 
Join Date: Sep 2009
Fan#: 69136
Location: Ottawa, Canada
What I Drive: 2003 ZX5 chrome yellow

Posts: 548
FF Reputation: 1 Leora83 Good Standing Member
Buy-Sell-Trade Rating: (0)
No CEL? I've only had the gas cap go bad once, and it threw a code for Large Evap Leak (can't remember the P number offhand). And if you're only ever filling halfway, it seems even less likely.
That said, a new cap will only set you back $15-20.

When you say it returns to normal after a few days, you mean RPMs of around 700-800 at idle? Or it just stops hanging at 3000?
Leora83 is offline  
    Reply With Quote
Reply

Bookmarks & Social Networks
-->
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:10 AM.


Copyright 2002-2014 FocusFanatics.com. All Rights Reserved : Terms of Use : Privacy Policy : Advertise Information

Focus Fanatics Ford Focus Forum offers many fun ways for you to engage with other Ford Focus Owners from across the world. Whether it be about the aftermarket performance modifications, technical how-to's, European tuned suspension or awesome fuel economy similar to the Acura TLX or Fiesta ST. You can find all Ford Focus and Focus ST related information here. Join our Ford Focus discussion forums and chat with local Focus enthusiasts in your area.