gas smell under hood 99 3.4L SE 32k miles

[dudeman135]

I have a 99 SE with the 3.4L V6 and only 32,000 miles. There is a noticeable gas smell. I took a brief look underneath the car and it looks good, no rusted fuel line or any leaks, just the smell in the engine area which is more noticable when popping the hood with the car running. After letting the car sit in the garage for an hour, went out popped the hood and no lingering gas odor. My wife mentioned that she notices the smell when running the heat or A/C also. Haven't noticed any other symptoms or warning lights. Anything major to be concerned about? Any ideas on possible cause/solution? Not real mechanically inclined, but can poke around a bit more if someone can point me in the right direction. Thanks!

[rixGAphx]

*Cliff's Notes* Always be concerned about gasoline odors, so you're correct to ask.

Why do you only have 32k miles?
Should be more like 84k to 105k for a 7-yr old car.

Regardless of the leak source, IMO noe of this is suitable for DIY repair.

Long, but simple enough DIY check so you don't get screwed when you go to a mechanic.
Originally posted by dudeman135
I have a 99 SE with the 3.4L V6 and only 32,000 miles. There is a noticeable gas smell.

Anything major to be concerned about?
Any ideas on possible cause/solution?
Not real mechanically inclined, but can poke around a bit more if someone can point me in the right direction. The GA (4-cyl and V6) has two fuel-handling systems in the engine bay:
* Pressurized fuel (to the fuel rail and injectors, in the top of the 'V') and return to the tank; and,
* Fuel vapor recovery (for emissions control).

The GA's monitoring of the emissions control is VERY good, and will ALWAYS illiminate the 'SES' light if there's a problem.
Drive to AutoZone/Checker/Etc. and they will plug-in to the computer port under your steering column, and read the computer codes (Diagnostic Trouble Codes, DTC's) for free.
One the inside of the passenger side front strut tower, there's a decal that shows every device and underhood tube of the Vapor Recovery System.
But that's not your problem at this time.

The GA does NOT monitor problems with the Fuel Pressure.
Even if the fuel pump isn't working at all, or if fuel is spewing all over everything, there won't be an 'SES' light directly related to teh fuel.
The fuel problem usually causes some OTHER problem, like misfire, and THAT will cause a DTC and SES light 'on'.

So, fuel odor and no 'SES' light = leak underhood at the pressurized supply or return line, or one of its devices.
Examination:
Open hood, look toward back of car. For purposes of THIS discussion only, 'right' is driverside and 'left' is passenger side (this is opposite of how car/boat/airplanes sides are usaully described).
Look at the engine; the flattish cast aluminum part on top, about 20" wide by 10" front-to-back and with the words 3400 SFI cast into it, is the Upper Intake Manifold, UIM.
Under it is the LOWER Intake Manifold, LIM.
The UIM aNd LIM are joined by bolts at the cylinder head, but you can see there's a narrow open space between them, down inside the 'V'.
There's a bunch of metal tubing and wiring in the space, and you can *barely* see the 3 fuel injectors for cylinders 2, 4, and 6 (across the front cylinderhead, left-to-right).
The metal tubing is kinda round on top and saquare on the sides and bottom; this is the fuel rail, and there's a twin about 6" behind it (but hidden).

At the right front of the UIM, there's a metal device with a small rubber tube angling rearward from it. The device kinda looks like half of an upside-down metal frozen orange juice can. This is the Fuel Pressure Regulator (FPR).
There are two screws (bolts?) that hold FPR sideways to the end of the aluminum fuel rail, and a tube bolted to the bottom of it with a brass compression fitting (like the plastic compression fitting that holds the water supply tube to the bottom of the bathroom toilet).
The metal tube is the Fuel Return line, and it goes back to the fuel tank.

Bend over the FPR, and look behind and below the throttle (the large black plastic/rubber bellows/square metal assembly from the air box to the UIM).
You'll see the right end of the rear fuel rail, and there's a metal tube and brass compression fitting entering it.
This tube is the Fuel Supply Line, and the Fuel Pump (inside the fuel tank) pumps fuel thru this tube into the fuel rail.

Look at the left (passenger) end of this same rear fuel rail, below the left side of the UIM.
There's a little metal tube that connects the rear fuel rail to the front, and there's a Schraeder valve (like a tire valve) with a plastic cap on it.
That's a test port, where a mechanic can attach a special gage to measure the fuel pressure.

Deep Breath :D :D

Possible leak points:
* Compression fittings of the supply or return fuel lines.
* Schraeder valve.
* Fittings of the little round tube from the rear fuel rail to the front rail.
* The O-rings (tiny donut-shaped rubber washers, at the top of each of the 6 fuel injectors where they plug-in to the fuel rail.
* The FPR-to-fuelrail connection (the two bolts).

Have a fire extinguisher handy.
Inspect the areas directly beneath the possible leak points for wetness.
Using a rag with no chemicals or solutions (other than mebbe 409 or Simple Green), clean the grease, oil, wetness, dust, whatever from those areas down to mostly-clean metal.
Have somebody sit in the driver seat and turn the key to 'on', but do NOT start it.
Examine each possible leak point agian, now looking for clear liquid to lightly dribble down.
If you find the leak location, stop and report back here.

* OR, quite often, the leak might be the rubber diaphragm sealed INSIDE the FPR.
* * Remember the little rubber hose that angles out the top of the FPR? Unplug it from its OTHER end (about 8" back on the UIM).
* * Gently suck on the hose. It *should* have no 'suckage', like sucking on a drinking straw with your finger over the end.
* * If air keeps coming, it will have strong taste of gasoline vapors.
* * Don't suck so hard as to get liquid gasoline in your mouth :eek:
Anything other than strong resistance (no suckage) means the rubber diaphragm has failed and the only solution is to replace the FPR with a new one.
$$$, check with your local parts store; check around, since prices really vary $50-200 mebbe?

You could just take it to a shop, but they often just say it's the FPR and charge a lot.

Hope this helps,
-Rick

[dudeman135]

Wow, nice description! Will print that out and check things out this weekend. We got the car from my mother in-law about 3 years ago, she only used the car to go back and forth to the store on occasion. They had a mini-van they used most of the time, so the GA only had 8000 miles on it when we got it in 2003. The other 24000 miles we've put since then. Again thanks, will poke around and see if I can diagnose things any further.

[coupe]

99 with 32K is amazing, its gotta be a ga record.

[dudeman135]

Again, great instructions. I visually examined the fuel rail (what I could see of it) the locations where the injectors connected up on the front 3 cylinders and all looked good there, no visible leaks. Followed along and found the FPR and pulled the rubber tube out of the other end where it connects to the UIM and sucked in and there was strong resistance.

I noticed some dampness on the outside of the FPR itself. Cleaned it off with a Qtip, started up the car and let it run for a minute or two and the area I cleaned off was again slightly damp. On the FPR there is that silver cap looking thing and the fuel is seeping out just underneath that onto cylindrical portion.

So, sound like it is the FPR in this case correct? If so, does $200 include parts and labor or just part? Thanks again.

Yes, it does have very few miles and since it had been garaged in western NY and now we're in FL, it's in real good shape. It is purple, but it's paid for and runs good, so I'll keep it. ;)

[rixGAphx]

I checked Chekecer recently, and found teh FPR for about $60-80 depending on brand, part only; you'll also need two O-rings, don't know the size.

Mebbe 1 hour labor, unless you hafta remove the UIM for access (another hour, + a pair of UIM gaskets, mebbe $10).

Good luck,
-Rick

[OldMike]

rixGAphx and dudeman135,
I was about to post the following, but did a search first. Great description, Rick. I, too, will do the inspection you describe and report back. Did you get it fixed dudeman135? And if so what was it - FPR? Cost?
Thanks, Mike


I have a 2002 Alero, Auto, 3.4L V6 with 51000 miles. When I turn it off after driving, there is an odor of gas under the hood. It seems to be strongest near the round black part with silver top labeled GM at the left end of the intake manifold (right if standing in front of car). Engine runs great and there are no trouble lights on. Any ideas?
Thanks,
Mike

[OldMike]

Report time: I found the metal supply line going into the rear fuel rail to have a thin coating of gas all over it. So I am going to remove a bunch of the wiring and the throttle body to gain access so I can see if the bolts are loose or the compression fitting has failed.

Questions: The small hard plastic tube coming out of the top of the FPR goes to the bottom of a small black box at the rear of the intake manifold. What is this black box? What is the small cannister located at the right end of the rear fuel rail (has a little silver metal label with GM on it)?

Thanks again for helping,
Mike