Notices
1973 - 1979 F-100 & Larger F-Series Trucks Discuss the Dentsides Ford Truck
Sponsored by:
Sponsored by: Moser

Gas Leak

Thread Tools
 
Search this Thread
 
Old Feb 3, 2014 | 08:43 AM
  #1  
76ClydeF100's Avatar
76ClydeF100
Thread Starter
|
Senior User
Joined: Dec 2013
Posts: 148
Likes: 0
Gas Leak

I noticed today when I got to work that there was gas on my rear quater panel where the gas cap is. So it was pretty easy to find out that there was a leak out of the cap. Its the original cap and pretty sure it could use a new rubber seal. Is it just better to get a after market cap and that solve my problem or is there something else more to this problem. That just seems like to easy of a fix. Its a fairly full tank of gas too just want to get opinions and see if anybody else has had this same problem and what they did to solve it. Multiple ways would be great to know.
 
Reply
Old Feb 3, 2014 | 09:29 AM
  #2  
77&79F250's Avatar
77&79F250
Moderator & parts slinger
Veteran: Army
15 Year Member
Community Builder
Liked
Joined: Feb 2007
Posts: 50,148
Likes: 5,783
From: S/W Missouri, Polk county
Club FTE Gold Member
Easiest is new cap, make sure it you have a vented one now, to get that style again.
 
Reply
Old Feb 3, 2014 | 09:43 AM
  #3  
fmc400's Avatar
fmc400
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Club FTE Gold Member
Gas shouldn't be coming out of there at all. You should be able to drive around without a cap at all and not have a leak (of course I don't recommend that). Your tank may not be venting properly. Does this truck have evaporative emissions?
 
Reply
Old Feb 3, 2014 | 09:43 AM
  #4  
76ClydeF100's Avatar
76ClydeF100
Thread Starter
|
Senior User
Joined: Dec 2013
Posts: 148
Likes: 0
Did the stock 76 f100 360s come with a vented one?
 
Reply
Old Feb 3, 2014 | 10:01 AM
  #5  
hickory1991's Avatar
hickory1991
Fleet Mechanic
15 Year Member
Photogenic
Photoriffic
Shutterbug
Joined: Feb 2011
Posts: 1,410
Likes: 42
From: Michigan
Club FTE Silver Member

My 76 F-250 4x4 has one. Don't know if it originally came that way though.
 
Reply
Old Feb 3, 2014 | 10:05 AM
  #6  
76ClydeF100's Avatar
76ClydeF100
Thread Starter
|
Senior User
Joined: Dec 2013
Posts: 148
Likes: 0
Fmc400 remind me what evap emissions are again...i have the smog ball on the drver side of the hood if that helps us.
 
Reply
Old Feb 3, 2014 | 10:12 AM
  #7  
fmc400's Avatar
fmc400
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Club FTE Gold Member
Evaporative emissions means you don't have a vented cap; instead there's a rollover valve on the top of the tank which leads to a charcoal canister via a passenger-side fuel vapor return line. The charcoal canister then runs up to the air cleaner using a purge valve.

The "smog ball" you mention is not smog equipment; it's a vacuum reservoir for the vacuum-operated HVAC controls. If you have cruise control, you may have a second canister.
 
Reply
Old Feb 3, 2014 | 10:16 AM
  #8  
76ClydeF100's Avatar
76ClydeF100
Thread Starter
|
Senior User
Joined: Dec 2013
Posts: 148
Likes: 0
Ok yes i do have emissions then...i was told wrong then by an ol shade tree about the smog ball...I wondered what that was.
 
Reply
FTE Stories

Ford Trucks for Ford Truck Enthusiasts

story-0

Top 10 Ford Truck Tragedies

 Joe Kucinski
story-1

AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

 Brett Foote
story-2

Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

 Michael S. Palmer
story-3

Ford's 2001 Explorer Sportsman Concept Looks For a New Home

 Verdad Gallardo
story-4

10 Best Ford Truck Engines We Miss the Most!

 Joe Kucinski
story-5

2026 Shelby F-150 Off-Road: Better Than a Raptor R?

 Brett Foote
story-6

2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

 Michael S. Palmer
story-7

10 Most Surprising 2026 Ford Truck Features!

 Joe Kucinski
story-8

Top 10 Ford Trucks Coming to Mecum Indy 2026

 Brett Foote
story-9

5 Best / 5 Worst Ford Truck Wheels of All Time

 Joe Kucinski
Old Feb 4, 2014 | 11:54 AM
  #9  
76ClydeF100's Avatar
76ClydeF100
Thread Starter
|
Senior User
Joined: Dec 2013
Posts: 148
Likes: 0
Fmc400 you left me hanging...how do i fix the tank? Where do I start?
 
Reply
Old Feb 4, 2014 | 12:10 PM
  #10  
77&79F250's Avatar
77&79F250
Moderator & parts slinger
Veteran: Army
15 Year Member
Community Builder
Liked
Joined: Feb 2007
Posts: 50,148
Likes: 5,783
From: S/W Missouri, Polk county
Club FTE Gold Member
Just go buy a new vented gas cap.....if you do or do not have a roll over valve with a vented gas cap, it should not vapor lock.
 
Reply
Old Feb 4, 2014 | 12:55 PM
  #11  
fmc400's Avatar
fmc400
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Club FTE Gold Member
Originally Posted by 76ClydeF100
Fmc400 you left me hanging...how do i fix the tank? Where do I start?
There wasn't a question in your last post, just a statement.

When you say you have "emissions," do you mean evaporative emissions? You've verified this truck has the charcoal canister along the frame rail in the engine bay?

If YES: the system cannot vent into the canister. Possible clogged return line or rollover valve. Or the cannister is not purging. It could be as simple as a leaking gas cap but your first post indicates you have liquid fuel running down the side of the bed. In my mind, pressure would have to be pretty high for that to happen. A vented gas cap is a quick way to bypass the whole system as explained above.

If NO: replace the gas cap.

This all assumes trace amounts of leaked fuel.
 
Reply
Old Feb 4, 2014 | 09:46 PM
  #12  
76ClydeF100's Avatar
76ClydeF100
Thread Starter
|
Senior User
Joined: Dec 2013
Posts: 148
Likes: 0
It is trace amounts of fuel. Is it worth it to get down there and find the culprit or just the vented cap? I dont want just fine I want the right way so should I get rid of all the emissions or replace and make sure its running right?
 
Reply
Old Feb 5, 2014 | 12:56 AM
  #13  
fmc400's Avatar
fmc400
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Club FTE Gold Member
It seems to me as though you answered your own question:

Originally Posted by 76ClydeF100
I want the right way
Originally Posted by 76ClydeF100
should I get rid of all the emissions or replace and make sure its running right?
It's ultimately up to you.
 
Reply
Old Feb 7, 2014 | 12:17 PM
  #14  
76ClydeF100's Avatar
76ClydeF100
Thread Starter
|
Senior User
Joined: Dec 2013
Posts: 148
Likes: 0
So I think I have found out why the emissions was not working and the leak was there to begin with. The gas cap was not making a complete seal. After driving a while I would suddenly see that the cap was at a different angle than when I had put it on there. I ended up purchasing a new cap that was for an emissions truck and no leak at all. The emissions in the truck are running just fine so I do not need to fix anything there.

The only thing that I do not like about the new cap is that it is a shiny new silver one. My truck is red and I would like to get it that color but also look as if the paint job was 40 years old as my truck does as well. Is there a good way of doing this? My idea was to go get rustoleum red rattle can paint that was close...spray 7-8 coats on the outside of the cap and then scuff it up with a scotchbrite pad. Has anyone ever done this or tried to make something new look old like that?
 
Reply
Old Feb 7, 2014 | 12:25 PM
  #15  
77&79F250's Avatar
77&79F250
Moderator & parts slinger
Veteran: Army
15 Year Member
Community Builder
Liked
Joined: Feb 2007
Posts: 50,148
Likes: 5,783
From: S/W Missouri, Polk county
Club FTE Gold Member
Glad to hear it was an easy fix. As far as antique paint tricks no, but that sounds like a good plan you have. I would practice it on some similar sheet metal first....
 
Reply



All times are GMT -5. The time now is 10:20 PM.

story-0
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE
story-1
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

And it might be even better than that.

By Brett Foote | 2026-05-18 19:26:42


VIEW MORE
story-2
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Slideshow: Does lowering an F-150 Lobo RUIN the ride quality?

By Michael S. Palmer | 2026-05-18 19:20:37


VIEW MORE
story-3
Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Slideshow: Ford's bizarre fishing-themed Explorer concept has resurfaced after spending decades largely forgotten.

By Verdad Gallardo | 2026-05-12 18:07:46


VIEW MORE
story-4
10 Best Ford Truck Engines We Miss the Most!

Slideshow: The 10 best Ford truck engines we miss the most.

By Joe Kucinski | 2026-05-12 13:09:47


VIEW MORE
story-5
2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Slideshow: first look at the 810 hp 2026 Shelby F-150 Off-Road!

By Brett Foote | 2026-05-12 12:50:07


VIEW MORE
story-6
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

Slideshow: Everything You Need to Know about the 2027 Super Duty Carhartt Package!

By Michael S. Palmer | 2026-05-07 17:51:06


VIEW MORE
story-7
10 Most Surprising 2026 Ford Truck Features!

Slideshow: 10 most surprising Ford truck options/features in 2026.

By Joe Kucinski | 2026-05-05 11:17:22


VIEW MORE
story-8
Top 10 Ford Trucks Coming to Mecum Indy 2026

Slideshow: Here are the top 10 Fords coming to Mecum Indy 2026.

By Brett Foote | 2026-05-04 13:49:49


VIEW MORE
story-9
5 Best / 5 Worst Ford Truck Wheels of All Time

Slideshow: The 5 best and 5 worst Ford truck wheels of all time

By Joe Kucinski | 2026-04-29 16:49:01


VIEW MORE