Smell gas fumes by filler cap

[Johnms]

I have noticed the smell of gas by the left rear of our 2007 Tahoe 5.3. There are no codes being thrown. Sometimes it takes a few extra turns of the starter to get it to run, but not always. No evidence of gas leaks that I can see, or on the ground. Any ideas?

Based upon my experiences with my 2009 Yukon 5.3, (I am not a mechanic) the smell of gas and longer starting times is likely an evap issue. There is a air line near the filler neck that is supposed to draw in those vapors into an evap canister, hold them in the canister until they can be reintroduced into the fuel rail to be burned. There is an evap solenoid that controls the vapor movement on the canister, and a purge value on the drivers side of the engine (on top) that creates the suction. As the system attempts to pull those vapors into the fuel rail, your engine is not getting the vapors and is hard to start. One of those components or very possible, one of the lines is probably failing. Many threads on this issue in the forum. I am surprised that you don't have a P0442 code. You might still have the codes pulled jus to check because sometimes the check engine light no longer works (mine does not).

 

[hagar]

Based upon my experiences with my 2009 Yukon 5.3, (I am not a mechanic) the smell of gas and longer starting times is likely an evap issue. There is a air line near the filler neck that is supposed to draw in those vapors into an evap canister, hold them in the canister until they can be reintroduced into the fuel rail to be burned. There is an evap solenoid that controls the vapor movement on the canister, and a purge value on the drivers side of the engine (on top) that creates the suction. As the system attempts to pull those vapors into the fuel rail, your engine is not getting the vapors and is hard to start. One of those components or very possible, one of the lines is probably failing. Many threads on this issue in the forum. I am surprised that you don't have a P0442 code. You might still have the codes pulled jus to check because sometimes the check engine light no longer works (mine does not).

He most likely doesn't have a code because it isn't an evap leak. An evap leak is a leak on the air volume of the fuel system, not the liquid volume of it.

If the leak is happening after the fuel has been sent out of the pump in the tank, that is no longer metered by the evap system. The only malfunction indicator that would help in that case, is a fuel pressure sensor that shows the vehicle isn't building enough pressure with initial key on, but his vehicle doesn't monitor fuel pressure.

And evap has nothing to do with starting the vehicle, there is no draw of fumes that goes into the fuel rail to help it start, the evaps only job is to relieve the pressure in the fuel tank. In the old days the tanks were vented to straight air, but they gave off fumes and stunk. All the evap does is open a solenoid when the tank gets pressure, and the engine sucks in the fumes. Heck, the evap might not even be open when the vehicle starts if there is no excess pressure, it certainly can't be relied upon to help start the vehicle.

 

[Jeff111]

I had the same symptom, smelled raw gas. No codes thrown. Dropped the tank, no problems. Noticed smell was extra strong after a fill-up, so after filling up I drove it hard for a few minutes to really slosh the gas around. I found some wet gas dripping from the spare tire. Got up under there. A squirrel had chewed both the vent line and filler line - the filler (thankfully) had only minor nibbles on the top side of the hose and wasn't breached, so I left it. The vent line must've tasted better (actually, probably the smaller diameter made biting easier) and that was where the hole was - replaced it and all is well.

 

[89Suburban]

Have any of you guys replaced a flex fuel pump? I am having a hard time trying to narrow down which pump I need. Looks like non-flex has 3 hose ports on it and flex only has 2? Are the retaining rings the same?

Mine is a flex according to the VIN#1GNFK130X7J144060 and RPO code #LMG. Right?

 

[Fless]

Yes, FF by the RPO code:

From what I see at Rock Auto I think you're correct about the two lines for FF vs 3 for gas. And the retaining rings appear to be the same online at GMPartsGiant.

Maybe @915_Tahoe can confirm with the VIN you posted.

 

[Geotrash]

Have any of you guys replaced a flex fuel pump? I am having a hard time trying to narrow down which pump I need. Looks like non-flex has 3 hose ports on it and flex only has 2? Are the retaining rings the same?

Mine is a flex according to the VIN#1GNFK130X7J144060 and RPO code #LMG. Right?

This looks like the one you need. Comes with a new O-ring, and you'll reuse your old retaining ring.

More Information for DELPHI FG0816

 

[89Suburban]

This looks like the one you need. Comes with a new O-ring, and you'll reuse your old retaining ring.

More Information for DELPHI FG0816

Yeah I was thinking that one too, thanks for the confirmation. I am going to order a new ring, just in case mine is rusted up and I get caught with my pants down. It's just a few extra bucks.

 

[Fless]

Might want to have new fuel tank strap mounting bolts ready if they're rusted up.

 

[89Suburban]

Might want to have new fuel tank strap mounting bolts ready if they're rusted up.

Yeah I still need to get under there and check those out as well. Also going to look at how the running board is mounted. Might be easier if I get that out of the way too?

 

[Fless]

Yeah I still need to get under there and check those out as well. Also going to look at how the running board is mounted. Might be easier if I get that out of the way too?

Not sure; mine's an '04 and they weren't in the way, but that's a different body.

 

[wjburken]

Yeah I still need to get under there and check those out as well. Also going to look at how the running board is mounted. Might be easier if I get that out of the way too?

I was able to drop the tank on my 2007 Yukon XL without any issues from the running boards other than needing to pump the jack a little higher.

 

[Con Man]

I have noticed the smell of gas by the left rear of our 2007 Tahoe 5.3. There are no codes being thrown. Sometimes it takes a few extra turns of the starter to get it to run, but not always. No evidence of gas leaks that I can see, or on the ground. Any ideas?

Yukon but same year and 5.3L. Don't wait to get fixed. Mine got worse until smelled inside and out. Had starting hesitation also. Blamed my son for hauling a leaky lawn mower around. Finally had to drop tank and fix.
Have paint damage around gas cap which may have been caused by fumes working on pain above tank.