Home » Public Forums » GMCnet » Raw fuel smell when stopping. (Ideas on where to check)
| Raw fuel smell when stopping. [message #306100] |
Mon, 29 August 2016 09:06  |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
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Just got back from an uneventful 200 mile trip camping. After a long list of things replaced. I now notice a raw fuel smell inside the coach when we were stopping for lights and stop signs. The smell goes away quick but wondering what / where it could be coming from.
The facts.
403. Non California emissions. Patterson Carb with 250 miles on it. New in carb filter, New in line filter just after the selector valve on the frame rail.
All new SAE 30R9 fuel hoses just installed a few weeks ago. Dropped both tanks and replaced everything.
New selector valve
Bounds insulated fuel hose going to the carb.
New fuel vapor separator.
When I was replacing hoses, I did blow out the metal line running across to the charcoal canister.
Canister it self is old, but was not wet or leaking and I also put in a new filter in the bottom of it.
Fuel pump has the 3rd line for a return, and a return line was run from the pump back to the filler neck with instructions from Dave Lenzi.
I can find no leaks of any kind anywhere, Running or sitting. I have fueled up 3 times and nothing is leaking when at the pump or just after fueling up. I can here a hiss at the vapor separator for a bit after getting gas. The smell only comes in when rolling to a stop. Once underway it goes away. It does not seem to make a difference if the tanks are full or half or 1/4. My thought was the rush of gas going into the front tank is spilling somewhere? but again, no leaks, drips or puddles. Once we come to a stop and turn the engine off there is no smell at all.
The only thing in the system not just replaced is the charcoal canister.
Any ideas out there on what or where to look?
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: [GMCnet] Raw fuel smell when stopping. [message #306101 is a reply to message #306100] |
Mon, 29 August 2016 09:20  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Bad gas cap comes to mind, as well as the fuel filler neck 1/2" burp line
hose. It is right next to your toll booth window. The correct cap breathes
in as the fuel is consumed, but is supposed to prevent expanding fuel from
exiting via the filler neck. When the gasket in the cap fails, they burp a
bit of fuel and smell. Also, the shoulder of the cap sometimes hangs up on
the pop rivet head in the outside of the filler neck. This prevents the
cap gasket from making a good seal on the neck opening. I have found
several replacement caps that did this. Cure is to grind the cap a bit
where it hits the rivet.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Aug 29, 2016 7:07 AM, "Wayne Rogewski" wrote:
> Just got back from an uneventful 200 mile trip camping. After a long list
> of things replaced. I now notice a raw fuel smell inside the coach when we
> were stopping for lights and stop signs. The smell goes away quick but
> wondering what / where it could be coming from.
>
> The facts.
> 403. Non California emissions. Patterson Carb with 250 miles on it. New
> in carb filter, New in line filter just after the selector valve on the
> frame rail.
> All new SAE 30R9 fuel hoses just installed a few weeks ago. Dropped both
> tanks and replaced everything.
> New selector valve
> Bounds insulated fuel hose going to the carb.
> New fuel vapor separator.
> When I was replacing hoses, I did blow out the metal line running across
> to the charcoal canister.
> Canister it self is old, but was not wet or leaking and I also put in a
> new filter in the bottom of it.
>
> Fuel pump has the 3rd line for a return, and a return line was run from
> the pump back to the filler neck with instructions from Dave Lenzi.
>
> I can find no leaks of any kind anywhere, Running or sitting. I have
> fueled up 3 times and nothing is leaking when at the pump or just after
> fueling up. I can here a hiss at the vapor separator for a bit after
> getting gas. The smell only comes in when rolling to a stop. Once
> underway
> it goes away. It does not seem to make a difference if the tanks are full
> or half or 1/4. My thought was the rush of gas going into the front tank
> is spilling somewhere? but again, no leaks, drips or puddles. Once we
> come to a stop and turn the engine off there is no smell at all.
>
> The only thing in the system not just replaced is the charcoal canister.
>
> Any ideas out there on what or where to look?
> --
> 77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson
> carb and dizzy.
> Mid Michigan
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
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| Re: Raw fuel smell when stopping. [message #306102 is a reply to message #306100] |
Mon, 29 August 2016 10:07 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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Thanks Jim,
I will take a look at the gas cap. I did remove the filler neck completely to install the fuel return line fitting. I was able to fit the neck back in and put in new rivets, but will take a look. Its the original cap as far as I can tell.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: Raw fuel smell when stopping. [message #306103 is a reply to message #306100] |
Mon, 29 August 2016 10:25 |
lw8000
Messages: 201
Registered: July 2012
Location: S.E. Michigan
Karma: 1
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Any backpressure at the gas cap when you went to remove it before a fill-up? I noticed something similar to this in hotter weather (~92 degrees or more) and I would only smell it when stopping like you mention. One time I could hear the noise at the cap itself. After turning off the engine it would cool off and the pressure would return to normal. Or if I opened the cap to relieve the pressure it would be fine for a while thereafter.
Only other thought might be the fuel hose connections at the pump and entering the filter at the carb and the compression fitting there as well as the fuel filter canister to the carb (nylon gasket OK?). I wonder if the fuel is evaporating on the manifold before it drips down to show any signs of a leak? Then again if that were happening I don't know if it would be enough to smell it.
Chris S. -
77 Kingsley, 3.70 FD, mostly OEM -
S.E. Michigan
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| Re: Raw fuel smell when stopping. [message #306105 is a reply to message #306103] |
Mon, 29 August 2016 10:40 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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Good suggestion, but No back pressure at the cap. This used to happen prior to me replacing all the fuel lines. But now there is no hiss or air escape when I open the cap.
The nylon gasket, filter and spring are in place in the carb housing and tight. As the carb is direct from Patterson. All the lines are tight and I did not see any fuel leaking anywhere around there. But also no indicators where fuel had been, cleaned up that area and then evaporated. So no trace of a fuel leak either.
Im thinking either the Cap, or that 1/2 inch burp hose. But the Hose was replaced and put in the same gentle bend as before. I suppose I could remove that hose and blow on it to see if its full of fuel. That would at least tell me fuel is up in the vent hose and pipe and hung up somewhere.
The other thing is when I last stopped for fuel I did not notice anything wet at the cap, Meaning if it was coming up to the cap it would be wet for at least a few seconds.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: [GMCnet] Raw fuel smell when stopping. [message #306117 is a reply to message #306103] |
Mon, 29 August 2016 11:45 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Have you replaced all the fuel lines?
Your having a venting issue.
The hose can be pinched not letting it vent to the vapor separator and or
the separator might be hanging up.
On Mon, Aug 29, 2016 at 8:25 AM, Chris S. wrote:
> Any backpressure at the gas cap when you went to remove it before a
> fill-up? I noticed something similar to this in hotter weather (~92
> degrees or
> more) and I would only smell it when stopping like you mention. One time
> I could hear the noise at the cap itself. After turning off the engine it
> would cool off and the pressure would return to normal. Or if I opened
> the cap to relieve the pressure it would be fine for a while thereafter.
>
> Only other thought might be the fuel hose connections at the pump and
> entering the filter at the carb and the compression fitting there as well
> as the
> fuel filter canister to the carb (nylon gasket OK?). I wonder if the fuel
> is evaporating on the manifold before it drips down to show any signs of a
> leak? Then again if that were happening I don't know if it would be
> enough to smell it.
> --
> Chris S. -
> 77 Kingsley, 3.70 FD, mostly OEM -
> S.E. Michigan
>
> _______________________________________________
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Raw fuel smell when stopping. [message #306120 is a reply to message #306100] |
Mon, 29 August 2016 12:40 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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Jim, Yes I replaced all of the fuel lines and vent lines when I dropped the tanks. and triple checked the correct line routing to the vapor separator. the PO had lost/ cut and capped the separator, so I now have one in place. When the job was done, I put in 6 gallons of fresh fuel to get me to the gas station. Just after pouring in the 6 gallons I could hear hissing from the separator, which at least told me it was hooked up and possibly expelling vapors? Im wondering if the larger vent hose may not be on a good angle to vent out? (the hose from the hard vent line on the filler neck, back to the tank area) So if I unhook the 1/2 inch hose from the filler neck and blow into it, I may blow fuel back into the tanks. if thats the case then I know I need to better route the vent line.
When I was putting the new lines in I did leave a bit of extra hose to be on the safe side. Not too much, maybe 3-4 inches or so. I Did not use the Poly Armour hard lines on the tops of the tanks.
Is there any test or procedure while the tanks are up to check for blockage in the vapor separator?
Thank you.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
[Updated on: Mon, 29 August 2016 12:42] Report message to a moderator |
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| Re: Raw fuel smell when stopping. [message #306121 is a reply to message #306120] |
Mon, 29 August 2016 13:19 |
bumpersticker
Messages: 60
Registered: February 2004
Location: Redondo Beach, CA
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Have you blocked your manifold crossovers? The manifold gets extremely
hot if the crossovers are not blocked. When you shut off the engine,
the engine heat soaks back into the carb and boils the gas out of the
carb bowl. After I blocked my x-overs the problem disappeared.
Bob Cook
78 Birchaven
75 Avion (In work)
Redondo Beach, CA
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| Re: Raw fuel smell when stopping. [message #306122 is a reply to message #306120] |
Mon, 29 August 2016 13:26 |
Hal StClair
Messages: 971
Registered: March 2013
Location: Rio Rancho NM
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AS Jim H suggested, I'd check the gas cap. I had issues with one that probably was a replacement and it didn't seat properly on the fill neck. I ended up grinding the cap slightly so the body of the cap didn't rub the base of the gas pocket and all was well. Before the diesel swap of course  .
Hal
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind, except you happen to be insane."
1977 Royale 101348,
1977 Royale 101586, Diesel powered,
1974 Eagle Bus 45',w/slideout,
Rio Rancho, NM
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| Re: Raw fuel smell when stopping. [message #306123 is a reply to message #306100] |
Mon, 29 August 2016 13:40 |
Tony Cook
Messages: 121
Registered: August 2014
Location: Torrance CA
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I concur with Bob Cook my crossovers have not been blocked and I too get a gassy smell after driving sometimes not bad but I do notice it after shutdown for a bit. Also my tanks and hoses have all been redone as well and cleaned canister/filter has been changed. Was shocked how much junk was in the canister.
Tony Cook
77' Kingsley ' SuperSession 77 '
Torrance Beach,CA
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| Re: Raw fuel smell when stopping. [message #306126 is a reply to message #306100] |
Mon, 29 August 2016 14:43 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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I looked at the cap at lunch today. Its got a good 1/4 inch of clearance before the body and rivets. When the cap is tight it still rides well above the body, and is not touching anything but the filler neck itself. I think the cap is OEM as it has two sets of tabs. the first set lines up with the filler neck slots, then half a turn and 1/4 inch up there is a second set of tabs. Once lined up it snugs down tight.
As for the cross overs, no they are not blocked to my knowledge, but the smell only comes for about 5 seconds when I roll to a stop. As soon as I am moving the smell is fully gone. While idling in driveway even after coming back from a 100 mile trip, there was no smell. So the engine was fully hot, Just idling. I pulled the hatch just to see if I could see anything dripping and there was nothing. It may be of importance that I back into the driveway, and the coach is level. The coach cooled down as I unpacked and still no raw fuel smell. No smell on fill ups either, other than normal vapors from the gas pump as fuel enters. The new vapor separator was dry, and all of the connections were dry.
While underway, even at low speeds, there is no raw fuel smell. Turning left or right or going straight from a stop sign is when I get the smell. A block down the road its gone. I could coast and there is no smell. As soon as I hit the brakes, and come to a stop, its very strong.
I should also say that prior to the new carb, fuel lines, etc. I did not notice the raw fuel smell. But I was also running without a vapor separator......
I will see about pulling the main vent hose off the fill neck tonight and if there is gas in it. That makes the most sense that the vent line may have gas in it. Moving forward then braking forces that fuel to run to the front of the coach and then up to the cap where I am getting a whiff of it.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: [GMCnet] Raw fuel smell when stopping. [message #306127 is a reply to message #306126] |
Mon, 29 August 2016 14:59 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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There is a liquid/vapor isolator in the rear drivers side wheel well. It
consists of a box with vapor lines entering it as well as exiting it. It
has a floating ball inside it that, in the case of liquid fuel entering it,
floats to the top and the ball seals the box and prevents liquid from
traveling through the vapor line to the charcoal cannister. These things
are known to crack and leak, the balls will become fuel laden and sink, the
lines will seep fuel, and probably a few more tricks. They can, and do,
leak fuel just ahead of the forward rear tire on the drivers side. Next
time you smell strong fuel smell, check that separator. Mine was bad, along
with the vapor lines. Just a couple more things to look at.
Jim Hupy
On Aug 29, 2016 12:44 PM, "Wayne Rogewski" wrote:
> I looked at the cap at lunch today. Its got a good 1/4 inch of clearance
> before the body and rivets. When the cap is tight it still rides well above
> the body, and is not touching anything but the filler neck itself. I
> think the cap is OEM as it has two sets of tabs. the first set lines up
> with the
> filler neck slots, then half a turn and 1/4 inch up there is a second set
> of tabs. Once lined up it snugs down tight.
>
> As for the cross overs, no they are not blocked to my knowledge, but the
> smell only comes for about 5 seconds when I roll to a stop. As soon as I am
> moving the smell is fully gone. While idling in driveway even after
> coming back from a 100 mile trip, there was no smell. So the engine was
> fully
> hot, Just idling. I pulled the hatch just to see if I could see anything
> dripping and there was nothing. It may be of importance that I back into
> the driveway, and the coach is level. The coach cooled down as I unpacked
> and still no raw fuel smell. No smell on fill ups either, other than
> normal vapors from the gas pump as fuel enters. The new vapor separator
> was dry, and all of the connections were dry.
>
> While underway, even at low speeds, there is no raw fuel smell. Turning
> left or right or going straight from a stop sign is when I get the smell.
> A
> block down the road its gone. I could coast and there is no smell. As
> soon as I hit the brakes, and come to a stop, its very strong.
>
>
> I should also say that prior to the new carb, fuel lines, etc. I did not
> notice the raw fuel smell. But I was also running without a vapor
> separator......
>
> I will see about pulling the main vent hose off the fill neck tonight and
> if there is gas in it. That makes the most sense that the vent line may
> have gas in it. Moving forward then braking forces that fuel to run to
> the front of the coach and then up to the cap where I am getting a whiff of
> it.
> --
> 77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson
> carb and dizzy.
> Mid Michigan
>
> _______________________________________________
> GMCnet mailing list
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> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: Raw fuel smell when stopping. [message #306128 is a reply to message #306100] |
Mon, 29 August 2016 15:27 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
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I will check the separator again, It was dry, and this one is new, as in it has 220 miles on it total.
When I first acquired the coach, there was no separator at all. The PO just cut both lines coming from the tanks near the rear wheel and put bolts in them......
When I renewed all the fuel lines a few weeks ago I reinstalled a brand new separator with all new hoses. Prior to putting it in I visually inspected it, no cracks, and the ball would rattle.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: [GMCnet] Raw fuel smell when stopping. [message #306131 is a reply to message #306128] |
Mon, 29 August 2016 16:10 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Well, that jus' about rules that one out. When you replaced the charcoal
cannister, did you hook the correct vacuum line up to it? If you have an
early 77 with a 455 engine NOT CALIFORNIA EMISSION EQUIPPED, then your
cannister should only have two lines. One from the separator valve, and one
to the carb. Not sure if it goes above the primary butterflies or below. If
your coach originally came with a 403 and was California emission equipped,
then these instructions do not apply. If it was, there will be two mounting
brackets for cannisters, because they had two of them. One did gas tank
vapors, the other did carb float bowl vapors. If you have that quadrajet,
then the bowl vents to the atmosphere and it could be the source of your
smell. Just clutching at straws here, long distance is hard to do for
smells.
Jim Hupy
On Aug 29, 2016 1:28 PM, "Wayne Rogewski" wrote:
> I will check the separator again, It was dry, and this one is new, as in
> it has 220 miles on it total.
>
> When I first acquired the coach, there was no separator at all. The PO
> just cut both lines coming from the tanks near the rear wheel and put bolts
> in
> them......
>
> When I renewed all the fuel lines a few weeks ago I reinstalled a brand
> new separator with all new hoses. Prior to putting it in I visually
> inspected
> it, no cracks, and the ball would rattle.
>
>
> --
> 77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson
> carb and dizzy.
> Mid Michigan
>
> _______________________________________________
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> Unsubscribe or Change List Options:
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| Re: Raw fuel smell when stopping. [message #306137 is a reply to message #306100] |
Mon, 29 August 2016 19:18 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
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I understand Jim, and thanks for helping troubleshoot this.
The engine is a 403, and is Non California, So it has one charcoal canister, That is the only part I have not replaced in the system thus far...
I took the 1/2 inch rubber hose off of the hard line filler neck vent tonight. I blew some air into it and I did hear fuel gurgling. when I let up I got a rush of air back through the vent. I blew in about 5-6 breaths plugging the hose in between and it was still gurgling. So Im somewhat confident that the vent line does have some gas in it currently. The tanks are both on 1/2 full at the moment.
One thing I mentioned, but thinking now maybe it does make a difference is that I installed a return line from the return port of the Toronado fuel pump. Prior to me dropping the tanks that return port was capped off, and I never liked that. So I ran a new line with Poly Armor closely following the factory fuel delivery hard line and R9 hose at the very ends. This return line dumps back into the filler neck. In speaking with Dave Lenzi I put the return fitting on the filler neck about 4 inches below the driver side floor so it is somewhat up high, and has plenty of room to flow back down the neck and into the tanks.
With the addition of this return line, does anyone think I now need a vented gas cap?? I suppose for giggles I could just leave the cap on a bit loose and see if that corrects the issue.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
[Updated on: Mon, 29 August 2016 19:21] Report message to a moderator |
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| Re: Raw fuel smell when stopping. [message #306146 is a reply to message #306137] |
Mon, 29 August 2016 23:55 |
Bullitthead
Messages: 1411
Registered: November 2013
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Perhaps your new return line is returning HEATED fuel back to the storage system and the extra vapors generated from the heating are escaping out the filler neck cap and connections since that is where you connected the line. If the tank liquid level is over the height of the fill pipe connection at the tank, those fumes are NOT wanting to go down that pipe and make their way to the vent line going to the carbon canister.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
[Updated on: Mon, 29 August 2016 23:57] Report message to a moderator |
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| Re: Raw fuel smell when stopping. [message #306210 is a reply to message #306100] |
Wed, 31 August 2016 10:37 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
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Gene and Terry.
Yes, I read and looked at the write up and used that when I did the fuel lines.
As for heated fuel returning, Yes, thats certainly possible, if not probable. The smell condition however only happens when Im stopping, and hence fuel is moving toward the front of the coach. When Underway there is no smell at all, Same with idling, and a fully warmed up engine, No smell, no leaks of any kind. When I removed the cap to refuel there was no whoosh of air coming out of the filler neck, so I have to think some venting is taking place.
My current thought is there is fuel trapped in the main vent hose which eventually leads to the 1/2 hose connected to the filler neck. When I blew into that hose I could hear fuel gurgling. The tanks are at 1/2 and there was resistance when I was blowing into it, so it wasnt like blowing I was blowing bubbles into the tank.
I will see about moving that vent hose up as high as possible inside the frame rail and make sure it is clear and has not dips or sags. Then conduct a test.
My thinking is, Its a somewhat closed system, I should be able to blow backwards (from my lungs, not an air compressor) on the main vent tube, and really should not be able to hear of feel fuel bubbling as the vent lines are on the tops of the tanks..... As new air enters the tanks, it should expand through the lines going to the vapor separator and eventually come out of the carbon canister. Does this sound about right. If not I wonder if my lines are crossed going to into the separator,
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: Raw fuel smell when stopping. [message #306563 is a reply to message #306100] |
Mon, 05 September 2016 17:54 |
77Royale
Messages: 461
Registered: June 2014
Location: Mid Michigan
Karma: 6
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Well Weekend update. Still have not found the 100% culprit.
I removed both hoses from the brand new vapor separator. both are clear and blowing air into them I did not have any resistance like I was blowing fuel anywhere. Shook the separator and can hear/feel the check ball in there.
Crawled under and as best as I could checked all the hoses on the top of the tanks. All appear to be free with nothing that I could tell was bound or pinched.
I looked at the stock metal fuel vent which runs along the frame rail. I did not move or alter this at all when I redid the hoses. It is not sagging and is secured all the way up to the filler neck.
I did see that the hose going from the top of the fuel vapor separator and eventually to the carbon canister does have a sag in it along the frame rail. But as I said, I removed that hose and blew into it and I was not pushing fuel up to the canister, (it was dry).
So the condition remains that when I remove the 1/2 rubber hose from the filler neck and blow into that, I can hear fuel gurgling down in the tanks. (Tanks are 1/2 full) Like when you blow on a a straw into a cup of water. Gurgle Gurgle. At one point I had the the opening of the filler vent tube plugged with my thumb and while Blowing additional air in to the hose I could hear the gas cap vent a bit under that bit of pressure. So perhaps my cap is still making a good seal. When I removed my thumb a bit of fuel came out the filler neck vent pipe.......
Im wondering if I hooked one of the vent lines up backward on the top of one of the tanks???? I know I marked both and was not rushed in the job, but that would make sense that as I blow air into the vent, one hose at one of the tanks is actually on the fuel pickup. and im blowing air back in through the sock down in the tank??? I dont know.
I can say I ran for at least 30 mins on each tank on my last trip, verified the new fuel selector I put in is working, and did not have any issues. So can anyone tell me for certain if I did have a vent line hooked up to the fuel pick up would the coach even run that long.
77 Royale, Rear Dry Bath. 403, 3.55 Final Drive, Lenzi goodies, Patterson carb and dizzy.
Mid Michigan
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| Re: Raw fuel smell when stopping. [message #306570 is a reply to message #306563] |
Mon, 05 September 2016 19:49 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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77Royale wrote on Mon, 05 September 2016 18:54Well Weekend update. Still have not found the 100% culprit.
<snip>
So the condition remains that when I remove the 1/2 rubber hose from the filler neck and blow into that, I can hear fuel gurgling down in the tanks.
=> This should not happen. Those vents are Teed by the front tank and both go into the sender ABOVE the fuel level. More below.
(Tanks are 1/2 full) Like when you blow on a a straw into a cup of water. Gurgle Gurgle. At one point I had the the opening of the filler vent tube plugged with my thumb and while Blowing additional air in to the hose I could hear the gas cap vent a bit under that bit of pressure. So perhaps my cap is still making a
good seal. When I removed my thumb a bit of fuel came out the filler neck vent pipe.......
=> This is not a surprise as there is a slug tap there that collects fuel.
Im wondering if I hooked one of the vent lines up backward on the top of one of the tanks???? I know I marked both and was not rushed in the job, but that would make sense that as I blow air into the vent, one hose at one of the tanks is actually on the fuel pickup. and im blowing air back in through the sock down in the tank??? I dont know.
I can say I ran for at least 30 mins on each tank on my last trip, verified the new fuel selector I put in is working, and did not have any issues. So can anyone tell me for certain if I did have a vent line hooked up to the fuel pick up would the coach even run that long.
Warren,
You should not have been able to blow bubbles...
If you got the vent and feed mixed, you could not have run 30 minutes !!!
Unless the selector valve was disfunctional. (I know you said you verified it, but maybe something came apart.)
When you switched tanks, did the level on the guage shift and did it move as expected on each tank??
As I understand it, the cap on the GMC fuel fill is not supposed to vent at less than 1+ psi, and that is not an easy blow.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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