Mysterious Fuel Leak

mo_dingo · Dec 20, 2003

Well, here is the story!

My uncle needed a ride to his work to pick up his car (long story). So, I pick him up at the house, and we get near his work, and he says he is smelling fuel.

I say, yeah, yeah, yeah, I know. With the top down, you smell everyone's car fumes. He says, NO, I smell unburnt fuel.

So, we get to his work, pop the hood, and I begin to smell fuel now!!!

My uncle works at a huge RV repair facility as a non-chassis mechanic, so we grabbed one of the mechanics there to take a look.

He says that with the "Open-Air K&N Air Filter" that I have, it makes it easier to smell gas fumes. I think he is smoking crack, but whatever.

We go over EVERY fuel line, and there is no evidence of a fuel leak anywhere! The main fuel lines look to be new, including the one on the FPR. I smell fuel vapor when I stick my nose next to the air intake tube.

He tells me to clean out my IAC valve, which should help. He tested the EGR, and it worked fine. The car is bone stock except for the filter.

MAF/IAT sensors are new. Clutch is new.

You know when you look down the highway when driving on a hot day, and it looks like the road is evaporating, well I look out my passenger side window, and I see (what looks like fuel vapor) out the window!!!

So, seeing as I can't find the leak by conventional means, what should I do? I heard about this stuff you put into the fuel tank that makes the fuel change color under a black light. Would this work? Should I try something else? Your opinions are appreciated, as usual!!!!
Thanks in advance!
Scott

mo_dingo · Dec 21, 2003

After driving it tonight, it seems as though the leak isn't as noticable now. I only smell gas when I put my nose directly in the engine bay.

I hate small leaks. GRRRR!!!!

Any help would be appreciated.
Scott

1fstgt · Dec 21, 2003

i've never heard of that stuff that you're talking about putting in your gas tank but if you can get it, that'd be the best way to find a leak. you might have to pull the upper intake off to inspect all the lines more closely and the o-rings on the fuel lines because you can't really see everything with the upper intake on.

good luck man!

mo_dingo · Dec 21, 2003

1fstgt said:
i've never heard of that stuff that you're talking about putting in your gas tank but if you can get it, that'd be the best way to find a leak. you might have to pull the upper intake off to inspect all the lines more closely and the o-rings on the fuel lines because you can't really see everything with the upper intake on.

good luck man!

Thanks!

I noticed that the upper blocks the second rail line for the injectors. That's new to me!!!!! Anyone know if it's a PITA to take the upper off? Is there a gasket I would need to replace afterwards?

I guess I will have to try the fuel stuff. I don't think autozone sells it, so I guess I will try NAPA!
Scott

1fstgt · Dec 21, 2003

pulling the upper is pretty easy to do. and you shouldn't have to buy the gasket if you're carefull and don't rip the old one.

like i said, i've never heard of that fuel system coloring stuff that you speak of so i bet if it even exists, it'll be hard to find.

SuperSync · Dec 21, 2003

mo_dingo said:
I noticed that the upper blocks the second rail line for the injectors. That's new to me!!!!! Anyone know if it's a PITA to take the upper off? Is there a gasket I would need to replace afterwards?

I know it's probably not 15 degrees with a 20-30 mph wind there but last year in these temps I had an injector o-ring decide to give it up and quit sealing good. Result = small fire under my driver's fuel rail. Luckily I was just warming the car up in the driveway and smelled the smoke coming through the heater vents. I was able to easily blow it out and park it until I could get the upper off to change the o-rings.

Maybe it's an o-ring, but who knows. They *do* go bad, and the results can be devistating. You will have to remove the upper to change either set of injector o-rings. It's simple to do and takes an hour or so (or at least that's what it took me). They are really simple (and cheap, like .08/ea) and may be the source of your problem.

I wouldn't let a smell of raw fuel that hasn't been there all along go unfound. Keep looking. An engine fire is really scary stuff.

SS

PS...I noticed a small puddle of fuel on my lower when I found the problem. If I pushed on the rail with my thumb and the system pressurized, fuel would spray out around the injector (#6 was my culprit).

jmuva44 · Dec 21, 2003

You may want to try replacing the ECT sensor. Its located near the thermostat housing. Replacing it helped with my overheating problem, rough idle and my gas smell INSIDE of my car. Now if you smell gas that strongly under the hood it may not be the problem. I dunno. But either way, its worth the $15 you spend on it cuz it helps a lot of areas.

mo_dingo · Dec 21, 2003

jmuva44 said:
You may want to try replacing the ECT sensor. Its located near the thermostat housing. Replacing it helped with my overheating problem, rough idle and my gas smell INSIDE of my car. Now if you smell gas that strongly under the hood it may not be the problem. I dunno. But either way, its worth the $15 you spend on it cuz it helps a lot of areas.

My brother has a 90 bronco w/ 351W, and when his ECT went bad, the car ran really rich. So you could smell gas, but it was through the exhaust, not the engine. And when it went bad, it spit out codes saying it was bad. But my car runs at the O in "normal" all day long. When it's hot outside, it might get to the r, but usually stays at the O.

Yeah, I can smell it under the hood, so I know there is a leak there. I wish it was a bigger leak so I could find it.

I noticed that when I first start my car, my idle is right at 700. Then after 10-15 seconds, it dips down to 500. I figured it was normal, but a friend w/ a same year/model mustang as me idle's fine.

The fuel leak may be the reason for low idle. But it's the #1 problem on my list now. I can figure out my pinging problem later.

I don't know where they sell the fuel coloring stuff, but I guess I will have to ask my uncle. He works for a RV repair facility, so I imagine he knows.

I didn't know the injectors has a rubber o-ring. That might be the problem. I assume if there was a leak at the upper/lower intake, that could cause a fuel leak too.

If you have any other suggestions, please let me know. Especially if you know where to purchase the fuel coloring stuff!!!!
Scott

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