Ok, let me start at the beginning. Right before I put my car up for the winter it started running rough. At idle it would act like it wanted to stall out and the longer I drove it it would act like it was missing and not running as smooth as it did when I first started it up. I figured maybe it was in need of a tune up.

I got it out a few weeks ago for the summer months and I called the shop where my girlfriend's dad works and asked him how much a tune up would be. He asked why I needed a tune up and I told him how it was running. He said to bring it in and they would investigate and see if there was some other problem at hand. I took it in, and he said that the fuel pump was going bad. They changed it out and I went to pick it up. It ran fine, but once I got it about 7 miles out of town (his shop is about 20 miles away from my town) the check engine light came on and it started jerking real bad. I pulled it off the road and it died and wouldn't restart. I called and they came back and got the car. He called back and said it looked like an injector was bad, so they replaced the injector and it started right up.

I went to pick it up this afternoon and it ran awesome. No problems going home, but I did notice about the time that I got it into my town I started to hear a sound in the rear of the car that reminded me of the sound that you make when you put your mouth over a pop bottle and blow into it. That's about the best way I can describe it. It would do that about every 35 seconds or so. Then when I pulled into my drive way and shut it off about every 20 seconds or so the car would make a noise like it was releasing air pressure. It was right around the gas tank area. I pulled the gas cap off and it had a lot of pressure built up and was giving off a lot of heat. There was also a really strong gas odor. I let the car sit for about 10 minutes or so and I went back out and it stopped making the air noise. Anybody have any idea what this would be? Like I said, the car ran really good other than the noises that it was making.

Thanks!

 

did you make sure that he put the correct injector/ fuel pump?

 

Yeah, a pretty familiar sound... sounds about like something blowing its nose back there.

Look in the tunnel across the car where the rear end is, just inboard of the left rear tire. You'll see a thing looks about like a UFO. It's a fuel tank vent valve. That's what's making the noise.

 

What's causing it? Is it serious? Is there anything I can do to fix it myself or am I going to have to take it back in to the shop?

 

Would it even run with the wrong parts? The car runs great now, it's just making those noises.

 

Just go to the dealer and buy one and swap it out.

Not the fuel pump so don't worry about that.

 

Is that why the fuel pump was making the noise after driving the car for a while? Was vent valve not venting properly? Also would that cause the extremely hot air to rush out when I took the gas cap off the car?

 

No.

Maybe.

No.

The pressure in the tank is normal. Required, even. Most newer cars will light the Check Engine light if it doesn't build up.

However if that valve is defective, as we know it is because of the noise it is making, it's possible that too much can be building up in there.


Just go get a new one and change it out and go from there.

It's also not impossible that you have a problem with your charcoal canister, as that's where most of the tank venting is supposed to take place.

 

I think you should check your charcoal canister in the front of the engine compartment that is where your fuel vapor gets cycled through so you don't have that problem. Emission cars don't have vented tanks they used that system. Me and my father (mechanic 35 years) were randomly talking about this today because we are encountering a similar type problem on my camaro

 

Last fall right before I put the car up for the winter I was installing some new hood struts and I noticed that the top hose to the canister wasn't hooked up. I don't know how long it had been unhooked and it very well could be that the previous owner unhooked it. Is there any benefit to unhooking it? Is it possible that the previous owner had these problems and unhooked it?

 

No.

After decades of futility in trying to understand why POs did ANYTHING that they did, I've given up trying to answer questions like this. Anything on the part of a PO is possible; the stupider the more likely it seems sometimes. But no, if the PO had the vagues remotest foggiest hint of a whiff of a glimpse of a clue off in the far distance about how the system actually works (not that s/he did....) the problem would most likely have been FIXED, not just hoses taken loose and left hanging. I'm guessing there's no connection between the 2 things, the one is a random failure, and the other is a random PO hack, maybe accidental.

 

Yes people unhook the charcoal filter when they use the far for racing. It is most likely why your gas vapors are not being filtered. And you should try to hook it back up and see if it fixes any of your noise problems

 

I hooked it back up as soon as I saw it was unhooked. I was just asking because I thought maybe the previous owner was having these problems and he unhooked it to remedy the problem rather than getting it fixed.

I've also found some people talking about having the same problems that I described when they were low on gas and they cleared up as long as they kept their gas tank over half full. When I was having the problem I had maybe 1/8 of a tank, 1/4 tops. A day later I completely filled the tank up and drove around for maybe 20-25 minutes and had no problems at all. I had the car out yesterday for a bit and didn't have any problems either.

 

thats great! well its a good thing that its hooked up again let me know if your having any more problems with that noise and ill get back to you