Recently I’ve been noticing a gas smell after parking my car after the drive home from work, but engine performance and mileage efficiency didn’t seem affected, and I found no visible evidence of leaking on the ground (nor in the engine, but I likely don’t know the right places to look).
Today, with the engine running, I looked around the engine to see if I could locate any gas leakage – I located the fuel pressure regulator (I think; a golf-ball sized acorn on the right of the engine with a hose coming in the top and a pipe coming out the bottom and going down and to the left) and didn’t see any leaking during my brief test. I’ll check it again after my drive home tonight. One new thing I did discover, though; while in park, when I slowly pressed on the accelerator, there would be a point where the engine started losing power and going into a rev/slowdown cycle: about a second or two of revving, then a half second of slowing down. This was while cold and in park; I’ve not experienced this in normal driving.
Do these symptoms lead any bright person here to be able to help me decide what part has failed, and whether it’s something I can fix myself or if I need to take it in to a mechanic?
Thanks!
When you fill up with gas and the pump clicks off do you try to “top it off” or quit? If you try to top it off, the carbon canister will most likely have liquid fuel in it. The EVAP system is vented when you shut off your car which could be your fuel smell. As far as how your engine runs in park, doesn’t mean anything. Are you having performance issues?
I generally don’t top off. Since the problem started, I went through a tank of gas (was hoping that might fix the problem) and had an oil change done (was hoping that might fix the problem). No performance issues, only the strangeness I described while revving in park, which I hoped might point to a particular component that might be failing.
Thanks!
The strange revving/slowing down cycle you are witnessing in “park” may be the engine’s rev limiter kicking in to prevent free revving and possible over-revving of the engine. Many vehicles have a 3,500 or 4,000 rpm “park” rev limiter. You could hold the gas pedal on the floor and the engine will never rev past that limit. I have had at least two vehicles with a 4,000 rpm rev limiter, and my sister’s '02 Grand Am also has a 4,000 rpm rev limiter. If you put the transmission in neutral, you can probably rev it all the way up to the redline. That’s how my sister’s car is, and that’s probably how your Impala is. If this is what you are getting, it is normal, and it probably won’t do it if you are in neutral. This will not be related to your fuel smell.
As for your fuel smell, if you cannot pinpoint it yourself, you need to take it to a mechanic to be properly diagnosed. A fuel leak is not something to mess around with and can be quite dangerous. Even NASA won’t launch the space shuttle if it’s leaking fuel!
Thanks for the explaining the revving red herring. If I can’t find a reason for the smell by this weekend, I’ll get my car into the shop ASAP.