ScorchedBird12

Past few days, since I started driving the car daily, I noticed I've been smelling gas every time I step out of the car. Also the past two weeks I filled the car twice. My commute based on google maps from home > first job > second job > home is 19.5 miles. So after 3 days from a full tank I went past the 1/4 mark before 1/2 on the fuel gauge. So based from the EPA combined mileage of 18mpg I thought this was right BUT out of those 19.5 miles about 1 mile is city driving.

But I still feel I'm running rich because of the strong gas smell I get every time I come out of the car and I feel like I'm burning more fuel than I should. I also drive spiritedly with occasional bouts of lead foot.

So based from my deductions, am I running rich or is this a typical thing that has been happening to our cars since it rolled out the factory? If I am what should I look at? Not trying to be a hypermiler with a V8...it just that everything seems right except for the smell of gas.

m16a2r

try to do a regular maintenance, change fluids, spark plugs, wires, fuel filter etc. check for old/cracked rubber hoses, especially running to a charcoal canister(if u still have it) check your gas cap for cracker rubber seal, maybe change distributor cap.

pima.1971

Check your spark plugs, they'll tell you if you're rich.

Black88Z

If you smell gas when you get out of the car, try to pinpoint where its coming from. Ive been fighting the same thing for a while, tackling problem after problem but still isnt perfect. is it coming from front or rear of car?

ScorchedBird12

It's coming from the rear. I even looked under the car for leaks and no luck.

freaky

SOUNDS LIKE YOUR CAP ISN'T SEALING PROPERLY

Black88Z

Most likely. I think iv heard of some auto parts stores presuure testing caps? Idk, seems like iv heard that somewhere.

You may not be able to see a leak tho, the exhust and the rear diff are under it, and theres a scrape shield there too i believe.

peterc005

Maybe the exhaust is sucking air, giving a lean reading via to the o2 sensor and the ECM is compensating by pumping more fuel?

eighty8

I had a similar problem that was cause by a disconnected air temperature sensor . Your check engine light isn't lit is it?

ScorchedBird12

Nope no check engine light.

spoazzy1

I was recently having the same issue. It seemed to be the strongest just after fueling up the tank so and I just replaced the gas cap and canister purge valve, and it has definitely seemed to make a difference. I am getting much better mileage now and increased throttle response. Just got new plugs, wires and cap & rotor as well as a new fuel filter to do a more thorough tune-up and see how that works.

I still have a slight smell, but it is nothing like it was, and I am not expecting to eliminate the smell completely because of my exhaust that is on there. The person I got the car from had 3" exhaust put on and removed and bypassed the cat, so I expect to have some smell, but at least now it doesn't smell like I spilled gas somewhere!

Mark Perez

Good afternoon im having a similar problem, i have a 1990 camaro rs 6 cylinder 3.1, not to long ago i replaced the distributor from the crank, egr, idle air control valve, throdle body position sensor, ignition coil, fuel pump, fuel filter, spark plugs, spark plug cables, and lately when i park the car and get out i can smell this strong scent of fuel coming out of my exhaust. I removed one of my spark plugs and the tips are covered with carbon all of them. So any one can give some advice on what i can do to find a solution to this problem thank you

camarosrock1989

iTrader: (1)

Ditto

spoazzy1

Upon diagnosing a VATS starting issue, I decided to give a thorough look over under the hood and found various vacuum lines and plastic fittings that were bad, most especially the ones from the EGR solenoid to the EGR and throttle body. Replaced them, and now the rough and high idle is gone, and the intense gas smell is too. I am still pulling a code 32 after hitting the highway, but that could just still be the exhaust. I figured though for what it is worth, if you are having this issue, its worth checking your vacuum system!

ASE doc

Is the build up on your plugs white and chalky? It may be from burning a little oil. This is common in older engines. As far as the fuel smell goes, from the front of the car is generally coming from the charcoal canister. remember these car are getting old and the canister is likely becoming contaminated with environmental debris, which reduces its ability to absorb hydrocarbons. This causes it to become saturated more easily. Also, as suggested, check all vacuum lines between the canister and the intake manifold. From the rear of the car, the most likely cause of fuel odor is the lines around the tank. Check the rubber sections of the fuel lines and the evap lines. A thorough tune is always good for efficient combustion and will help reduce unburned fuel in the exhaust.

gta_knight

ive had this problem on my 87 for a while now too

i first thought something was up when i put a new fuel cap on, but when i remove it, it doesnt let off a 'hiss' anymore, whereas it always used to when removing the cap. instead when the car is running i can hear a hiss coming from under the car, me and a friend got under it last night and the hiss is coming from the actual tank so he thinks thats just the normal noise the electrical fuel pump makes when its working ? all the hoses and pipes are fine, theres nothing leaking, and i also took off the white valve thing as that was black and clogged up so thats all nice and clean now

im not sure if its always done that before, i think i only noticed when is started investigating the smell of fuel from the back of the car.

But anyway, my fuel cap should let off pressure when i open it yeah ?

Black88Z

My fuel pumps never making a "hissing" sound, its always been a "whurring" sound. Thats the problem with trying to describe sounds though, we may be talking about the same sound just using different words to describe it lol

I have always wondered about the gas cap hiss too. I had an old cap that didnt do it but it didnt sit right on the filler neck. So i got another one, this was a vented, and the car literlly lost power. It wasnt as torquey and it was noticably weaker. I took it back and got a NON-vented cap and its power was back, but theres still no hiss sound when i take the cap off. IIRC, the tpi engines require the non-vented caps because of the need of higher fuel pressure. I had tried autozone and they didnt have it, advance auto didnt, finally pep boys did. (funny that pep boys would have something like that but AZ and AA didnt huh?)

TTOP350

iTrader: (8)

There is also a tank psi valve under the car up by the tank. It can go go bad and stick open or closed. Its white or off white and clipped into a bracket on the frame rail.

ASE doc

Fuel tank pressure has nothing to do with fuel pressure. Tank pressure is a side effect of the Evaporative Emissions system. EVAP system's charcoal canister collects vapors that develop in the tank and stores them to be burned by the engine. Tod do this it has to contain the vapors from venting into the atmosphere. If you noticed a performance difference with a vented cap, you may have a restricted or saturated charcoal canister. With the canister working normally, the tank wouldn't develop enough pressure that having the cap vented would make that much difference.

The vent valve that TTOP 350 refers to is just a safety pressure release to prevent too high vacuum or pressure in the tank in case the canister becomes clogged.

Black88Z

Thats very possible, and interesting you would say that. I have always had a slight fuel odor from the front of the car, stronger if i run it hard. Ill check the canister out. Thanks Doc!

KITT1983

iTrader: (3)

So what was it?

rsitser

Any updates on this? I am have the same problem with an 89 305 TBI. I replaced the fuel pump and fuel regulator. And when I take the cap off, sounds like it has vacuum. Maybe my cap is bad.