• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech

Gas Overflowing Through Gas Cap On Hot Days

  • Thread starter Thread starter NFLjunkeez
  • Start date Start date Jul 17, 2014
N

NFLjunkeez

Member
Feb 16, 2013
30
0
7
Jul 17, 2014
#1
  • Jul 17, 2014
  • #1
Why is it that no matter how full my gas tank is on my 91 mustang, gas always leaks out through the gas cap when driving for more than 20 minutes in 100°+ weather.

It's quite a bit too. When i open the gas tank door the entire section around the cap (couple inches deep) is flooded with gas as it's trying to escape through the overflow hose.

My obvious conclusion is a bad gas cap. But... Could there be another reason as to why it's doing this?
 
J

jka

5 Year Member
Jan 17, 2010
339
23
29
Jul 17, 2014
#2
  • Jul 17, 2014
  • #2
You need to buy a vented gas cap.
 

Onefine88

Previously 89SSC18
10 Year Member
Aug 3, 2006
1,422
796
154
Jul 18, 2014
#3
  • Jul 18, 2014
  • #3
jka said:
You need to buy a vented gas cap.
Click to expand...
I'm pretty sure he already has a "well vented" gas gap. LOL
-Try a new gas cap. Also, the tank vent line that runs from the tank up front to the charcoal canister may be clogged. Or there could be a problem with the charcoal canister itself. If either of these are stopped up it will definitely pressurize the tank.
Good Luck
 
J

jka

5 Year Member
Jan 17, 2010
339
23
29
Jul 18, 2014
#4
  • Jul 18, 2014
  • #4
Onefine88 said:
I'm pretty sure he already has a "well vented" gas gap. LOL
-Try a new gas cap. Also, the tank vent line that runs from the tank up front to the charcoal canister may be clogged. Or there could be a problem with the charcoal canister itself. If either of these are stopped up it will definitely pressurize the tank.
Good Luck
Click to expand...
I know his gas cap is vented LOL..it came from the factory with one ..i was trying to say he my need a new vented gas cap because i had the same problem before. But not saying that's his problem but it was my problem. I gave him something cheap and easy to try if that does not work you are right about the charcoal canister.
 

jrichker

StangNet's favorite TOOL
In Remembrance. Thank you for your contributions
Mar 10, 2000
27,512
2,813
234
Dublin GA
Jul 18, 2014
#5
  • Jul 18, 2014
  • #5
Charcoal canister plumbing - one 3/8" tube from the bottom of the upper manifold to the rubber hose. Rubber hose connects to one side of the canister solenoid valve. Other side of the solenoid valve connects to one side of the canister. The other side of the canister connects to a rubber hose that connects to a line that goes all the way back to the gas tank. There is an electrical connector coming from the passenger side injector harness near #1 injector that plugs into the canister solenoid valve. It's purpose is to vent the gas tank. The solenoid valve opens at cruse to provide some extra fuel. The canister is normally mounted on the passenger side frame rail near the smog pump pulley.



It does not weigh but a pound or so and helps richen up the cruse mixture. It draws no HP & keeps the car from smelling like gasoline in a closed garage. So with all these good things and no bad ones, why not hook it up & use it?


The purge valve solenoid connector is a dangling wire that is near the ECT sensor and oil filler on the passenger side rocker cover. The actual solenoid valve is down next to the carbon canister. There is about 12"-16" of wire that runs parallel to the canister vent hose that comes off the bottom side of the upper intake manifold. That hose connects one port of the solenoid valve; the other port connects to the carbon canister.

The purge valve solenoid should be available at your local auto parts store.

Purge valve solenoid:



The carbon canister is normally mounted on the passenger side frame rail near the smog pump pulley.
Carbon Canister:
 
Reactions: NFLjunkeez
N

NFLjunkeez

Member
Feb 16, 2013
30
0
7
Jul 19, 2014
#6
  • Jul 19, 2014
  • #6
jrichker said:
The carbon canister is normally mounted on the passenger side frame rail near the smog pump pulley.
Carbon Canister:
Click to expand...

My car has ran rich since i got it. There's a heavy gas smell every time i drive it and because it's parked in my garage, the fumes are overpowering.

Can this be caused by a clogged charcoal canister?
 

jrichker

StangNet's favorite TOOL
In Remembrance. Thank you for your contributions
Mar 10, 2000
27,512
2,813
234
Dublin GA
Jul 20, 2014
#7
  • Jul 20, 2014
  • #7
NFLjunkeez said:
My car has ran rich since i got it. There's a heavy gas smell every time i drive it and because it's parked in my garage, the fumes are overpowering.

Can this be caused by a clogged charcoal canister?
Click to expand...
Clogged, missing or not connected properly will cause a gasoline order in closed spaces.
 
You must log in or register to reply here.

Similar threads

M
01 mustang 3.8 fuel pressure issue
  • Mhaley2006
  • May 29, 2026
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
158
1996 - 2004 SN95 Mustang -General/Talk- May 29, 2026
Mhaley2006
M
B
'03 GT Fuel Pump/Pressure/Delivery Issue
  • Brodach
  • Oct 21, 2025
  • SN95 4.6L Mustang Tech
Replies
8
Views
916
SN95 4.6L Mustang Tech Oct 31, 2025
gkomo
M
New from North Texas
  • MFReeves
  • Aug 26, 2025
  • The Welcome Wagon
Replies
9
Views
533
The Welcome Wagon Sep 22, 2025
nickyb
M
Fox Slow filling gas tank
  • mcalvo
  • Oct 17, 2023
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
4
Views
2K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Oct 20, 2023
85GTStangGuy
WTB/Trade Looking for a T-Top Hatch. Possible convertible trade? (Rhode Island)
  • 7upper
  • Mar 18, 2025
  • Fox Body Mustangs For Sale (1979-93)
Replies
0
Views
327
Fox Body Mustangs For Sale (1979-93) Mar 18, 2025
7upper
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • Fox 5.0 Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?