When it rains.....see if you can guess the cause
 

Throwing this one out as a quiz, especially since this doesn't happen often.

I know whats wrong and have already ordered the part(s), just curious to see what you guess.

Symptoms/Diagnostics

Driving home last night, catch the vague smell of gasoline, had just filled up the tank, and I really fill it up, so don't think too much about it. Get home, park car in garage.

Come out an hour later for cigarette, garage reeks of gasoline.

Check fuel pump (left cover off for a few days to verify no leaks, just changed check valve last weekend) Dry as a bone.

Open hood, Strong odor of gasoline, hear a slight hissing, bubbling noise.

Other symptoms:

car now idles a bit rougher, but still within spec, when car sits at idle running, there is a STRONG odor of gasoline.

Power is about 300 RPM's "off" of where it should be.

Sometimes it takes a few cranks to get it going, fuel pressure is within spec when running.

very small wet spot of fuel left behind when the car sits for a while.

Hints

Fuel pump is working flawlessly, check valve is new.
Tank filter is clean
Fuel filter is new (5 days old)
gas is of good quality

No prize or anything, just kind of curious as to what answers I get.

AFJuvat

my guess is fuel pressure regulator

check for small leak above trans in fuel line. and I smoke too.
Dont when you smell gas fumes.. Its bad. boom.
Fuel rail OK? no drips?- the hissing sounds like a fuel pressure issue somewhere.

Both are incorrect. Fuel rail is not leaking.

Hint #2

repairs are limited to the engine bay.

AFJuvat

sounds like fuel damper except for fuel leak. my guess would be a bad fuel vapor valve

Humm... I thought it was #2 where my gas leak very bad but my guess is #20 or #19. :D

http://www.pelicanparts.com/944/944_...3-85/Pic13.jpg

Spark plugs aren't burning all of the fuel...leaks out the exhaust?

I'm the last person you want diagnosing a car. :)

no, that would be me. faulty fuel injector?

<img src="http://www.pelicanparts.com/MotorCity/blackfoot/turbo_120%20lighter.jpg">

me too....

but I like this answer...

You filled up, unlike normal. Some fuel went into fuel overflow tube, which is also spliced (right word?) into sunroof drain. Smell of gas comes from stopped up tube, which is not allowing the fuel to drain.

fuel dampner leaking into vacuum lines

oops, I missed the hissing bubbling sound... I change my guess to a broken/cracked fuel rail.

AFJuvat said the Fuel rail is not leaking. :)

Hey bud you also missed: "Both are incorrect. Fuel rail is not leaking. Hint #2 repairs are limited to the engine bay" come on already we're anxious to hear what it was!

I know, I read that right after I posted the second one... And then I decided instead of guessing again, I would just shut up, lol. I've already proven myself an idiot LOL... jeez, if I just read the whole thing the first time... hehe

It's a good guess since there really isn't too many things to leak fuel in the engine bay. First the hoses, then the fuel rail, the o-rings between the rail and injectors, the front fuel rail cap and ball, dampner, regulator, and the hoses/hard lines in between(depending on year and model). The only thing that kinda stumps me is the actual "very small wet spot of fuel", has too trickle down the cyl. head and down the front/rear of the motor, unless it's by the fuel lines and dropping by the exhaust-- ooh scary@! but if that was the case I don't think he'd be testing the idle and such if it was dripping on the exhaust.

I just repaired a leaking fuel injector last month. I had all the symptoms you said except no hissing sound and and i guess my difference in performance was similar to what you describe. Fuel began to well up from the injector seal and saturate the intake side of the engine. Most of the gas would evaporate away before it could pool up enough to drip. The leak would eventually depressurize the fuel rail, causing the need to double crank over the engine to restart it. I think the housing of my injector is what failed, around the seal. If yours was to fail higher up on the injector, it might make an audible hiss or bubbling noise....... so I'm going with injector too.

BINGO!

#2 injector - Seal failure, coupled with a stuck injector

Fuel bubbling out of the injector hole.

Honorable Mention, Bob's 944 for describing it exactly

AFJuvat

Holy crap! me mr know nothing was going to take a random guess and say that or the fuel rail but I said na I am just going to look dumb. I guess I should have said something!

well, i'd like to take credit, but in this case it was just a total guess. the only other main fuel system component in engine bay that nobody had mentioned were the injectors.

when it comes to mechanics & diagnosis, i'm clueless, and i hope to prove it in the future.

<img src="http://www.pelicanparts.com/MotorCity/blackfoot/turbo_120%20lighter.jpg">

yeah I was spitting the random guess to. Thats why I didn't say it. I thaught I would have been waaaaayyyy wrong. I guess not ;)

Always take a guess even if you don't know the answer, you may not always be right, but at least if you investigate and eliminate something you that is what it isn't.

You always have to start somewhere, especially when you get the line "my car is broken!", or the almost as equally unhelpful without a lot more detail "My car won't start!"

If these are popular, I can post more of them, even can post some from ones we get in the shop.

AFJuvat

I would have guessed fuel return line. How did gas puddle up behind the car?

where was the puddle?

does this happen only when you you fill your tank?..

I didn't say there was a puddle behind the car, I said there was a puddle left behind when the car sits for a while.

AFJuvat

Juvy,
did your car ever have any of the warranty work done to it?..

You should quit smoking.

so should I.. Thanks Lawrence..

I'm down to about a pack of ultralights every 2 to 3 days, from a high of about close to 1.5 to 2 packs of regulars a day. I will also mention that one person in my immidiate family is a doctor, and she occasionally smokes (my mother), my cousin is also a surgeon and she smokes too. Those are the only doctors in my family, and the only people who smoke aside from me! Interesting, I thought...

Anyway, I've had two 944 turbo injectors fail and leak externally too. Perhaps they're getting old... Mine had 180+k miles on them.
Ahmet

Yep, pulled the history when I bought it - all of the fuel system updates are in place.

Yeah, I am working myself up to quitting here soon. Getting too damn expensive.

AFJuvat

cigarettes or the porsche? :-)

<img src="http://www.pelicanparts.com/MotorCity/blackfoot/turbo_120%20lighter.jpg">

Flashlight.. What flashlight? Let me just go over here and get my lighter and we'll find that fuel leak,,,

Cigarettes.

Can't give up on the P cars.

AFJuvat

More stumpers like this one?
 

Hey AF,

Yep, I like these stories/questions of yours. Really liked the one about the guy with the 911 that burned up his engine by ignoring his oil levels. Brought it in and you did the initial diag.

Keep 'em coming.