Home » Public Forums » GMCnet » Fuel Odor
| Fuel Odor [message #283688] |
Sat, 01 August 2015 19:05  |
bhayes
Messages: 263
Registered: March 2010
Karma: 1
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I took our GMC up to scout camp last night, and when I parked, there was a very strong gas odor around the middle of the coach (right about over the gas tanks). Also, when I stepped on the floor near the refrigerator, there was a metallic popping noise, like the top of one of the tanks was pressing right up against the floor. There was no gas odor outside of the coach, and no leaks that I could see.
The odor eventually died down after opening all of the windows and running the Fantastic Vent Fan, and the metallic popping sound eventually went away, but the same thing happened once we got the coach home today.
Not sure where to start on this one. I replaced the fuel separator in the drivers side rear wheel well about a year ago after it broke, so I'm going to check that again.
Any other ideas on what to look for?
Bryan Hayes
'76 Eleganza II
Salt Lake City, Utah
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| Re: Fuel Odor [message #283716 is a reply to message #283688] |
Sun, 02 August 2015 09:43  |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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bhayes wrote on Sat, 01 August 2015 17:05I took our GMC up to scout camp last night, and when I parked, there was a very strong gas odor around the middle of the coach (right about over the gas tanks). Also, when I stepped on the floor near the refrigerator, there was a metallic popping noise, like the top of one of the tanks was pressing right up against the floor. There was no gas odor outside of the coach, and no leaks that I could see.
The odor eventually died down after opening all of the windows and running the Fantastic Vent Fan, and the metallic popping sound eventually went away, but the same thing happened once we got the coach home today.
Not sure where to start on this one. I replaced the fuel separator in the drivers side rear wheel well about a year ago after it broke, so I'm going to check that again.
Any other ideas on what to look for?
Brian,
I had a '78 that had a bad separator valve. The tanks would build pressure and swell. Swell so much the fuel gauge reading went down. So, your tank could be swelling. Doesn't take much pressure. You say "up" to camp so altitude can add to the situation.
But, the gas smell means that something is letting off the pressure under your coach and pain as it is that needs to be chased down. It may be that it is the separator hose, just ahead of the left front bogie, in the rear fender well.
Good luck.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: Fuel Odor [message #283717 is a reply to message #283688] |
Sun, 02 August 2015 10:00 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Senior Member |
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bhayes wrote on Sat, 01 August 2015 17:05I took our GMC up to scout camp last night, and when I parked, there was a very strong gas odor around the middle of the coach (right about over the gas tanks). Also, when I stepped on the floor near the refrigerator, there was a metallic popping noise, like the top of one of the tanks was pressing right up against the floor. There was no gas odor outside of the coach, and no leaks that I could see.
The odor eventually died down after opening all of the windows and running the Fantastic Vent Fan, and the metallic popping sound eventually went away, but the same thing happened once we got the coach home today.
Not sure where to start on this one. I replaced the fuel separator in the drivers side rear wheel well about a year ago after it broke, so I'm going to check that again.
Any other ideas on what to look for?
Bryan,
I can't imagine the floor flexing enough to contact the gas tank. It is pretty solid. Not sure what the metallic popping noise was, but the fuel smell might just be fumes coming from your charcoal canister. That smell would come from the front area, not the middle though. The other possibility is that gas may be draining out of your carburetor into the manifold from leaky well plugs. The gas will evaporate inside the hot manifold and the fumes will work their way out of the carb and air cleaner, but again, the smell would be more noticeable toward the front of the coach.
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: Fuel Odor [message #283726 is a reply to message #283688] |
Sun, 02 August 2015 11:34 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Or failing old type ( not modern barrier type) rubber fuel hose at any of the places it is used. It becomes like that garden soaker hose and weeps gas. Needs quick attention.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Fuel Odor [message #283752 is a reply to message #283688] |
Sun, 02 August 2015 14:20 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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bhayes wrote on Sat, 01 August 2015 17:05
Not sure where to start on this one. I replaced the fuel separator in the drivers side rear wheel well about a year ago after it broke, so I'm going to check that again.
Any other ideas on what to look for?
Sorry I didn't read the post carefully enough. I was in a hurry for my Sunday morning.
Yes, look at it again, in case a clamp is leaking.
Is it possible that someone created the hole in the floor of your coach, to get to the tank senders and that floor covering is making the noise.
If you do have to lower the tanks, I wholeheartedly give my vote for Matt Collie's strap technique for lowering the tanks. These straps, hooks on one cross member and the ratchet hook on the other side, works so handily it really makes this unhandy job much easier. The last one I helped with was done easily with the coach just up on blocks. Tank came down evenly and easily and went back up the same way.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
[Updated on: Sun, 02 August 2015 14:29] Report message to a moderator |
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| Re: [GMCnet] Fuel Odor [message #283992 is a reply to message #283983] |
Wed, 05 August 2015 00:39 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Bryan,
It appears that the surface your fuel / vapor separator is bolted to is not flat, it dented the rear and stressed it causing the
bottom lip to separate. This is a SWAG!
Scientific
Wild
Ass
Guess!
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Bryan Hayes
It looks like the problem is the fuel separator valve again, which is only a year old. The bottom lip is separated, and the back of
it is "dented," like it got hot, the plastic got soft, and someone pushed their thumb into it.
Here are the photos:
http://www.gmcmhphotos.com/photos/member-galleries/p58848-bad-fuel-separator-valve.html
Now I'm wondering why it failed.
Bryan
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Fuel Odor [message #283999 is a reply to message #283992] |
Wed, 05 August 2015 06:21 |
Jim at the Co-op
Messages: 291
Registered: May 2014
Location: Orlando Florida
Karma: 2
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How much longer has it lasted than any engineer ever figured on? If your
fuel system has not been overhauled in the past 7 years.... everyone used
standard goof grade fuel hose... with ethanol now in our fuels, those hoses
have been attacked by the alcohol ... they are hard, cracked and begging to
be replaced. You can have all sorts of issues.... if your body pads are
crushed or missing, you very will could hear the bottom of the floor
flexing the top of the tank. Get under there and look around for all this
On Wed, Aug 5, 2015 at 1:39 AM, Robert Mueller
wrote:
> Bryan,
>
> It appears that the surface your fuel / vapor separator is bolted to is
> not flat, it dented the rear and stressed it causing the
> bottom lip to separate. This is a SWAG!
>
> Scientific
> Wild
> Ass
> Guess!
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
> -----Original Message-----
> From: Bryan Hayes
>
> It looks like the problem is the fuel separator valve again, which is only
> a year old. The bottom lip is separated, and the back of
> it is "dented," like it got hot, the plastic got soft, and someone pushed
> their thumb into it.
>
> Here are the photos:
>
> http://www.gmcmhphotos.com/photos/member-galleries/p58848-bad-fuel-separator-valve.html
>
> Now I'm wondering why it failed.
>
> Bryan
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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