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TJ Gas smell driving me nuts!

14K views 8 replies 6 participants last post by  Digger84 
#1 ·
Hi all. I have been chasing a gas smell for about two months. I *think* it is coming from the front, but I honestly can't be sure; it is very elusive. It is a "fresh gas" smell and not a dirty fume sort of smell.

Here is what I have done so far:

Dropped the tank (three times -- don't ask) and replaced the filler and overflow hoses, the vent lines, and the gas feed line. I also replaced the large round seal around the fuel pump and inspected the locking collar. Pressure/smoke tested the tank with a home made smoke machine and didn't find any leaks. I even removed the skid plate and inspected every inch for a damaged area. Nothing.

I have inspected -- inch by inch -- the fuel line running all the way from the tank up to the rail. Done so with the engine off and with it running. Sprayed soap solution on all fittings. Nothing.

Replaced the injector O rings and cleaned all the mating surfaces. Rail looks good. Nothing obviously wrong with the rail damper. Isolated the rail (while installed) from the fuel line and smoke tested. Nothing. Also pressurized with air at 40 lbs and did not find anything.

I've smoke tested the evap system and found a few minor leaks. (One was the injector O ring (above). Replaced/fixed the others. I've inspected the LDP and the purge valve. Didn't find anything visible or anything that smelled. Checked all lines and elbows/fittings. Purge valve is ticking away when engine runs. Vapor canister does not have any liquid fuel and actually does not smell too bad when hoses are removed.

I did a leak down test off the schrader on the rail. When running, the pressure is a solid 48. It DOES leak down almost immediately when I shut off the engine. I suspect a bad check valve in the pump, even though no other symptoms of bad pressure. (I let the pressure build for a few secs before cranking to start.) I don't understand why a check valve problem would result in a gas smell, so I am trying to not let that test distract me from finding the source of the leak.

More about the smell -- all driving done with soft top on and AC blowing. On recirculate, the smell is not too bad in the cabin. On Fresh, it is noticeable inside. Outside the vehicle I can smell gas strongly from up front. Only occasionally near the rear but that could just be things blowing around. Noticeable right after driving, and even 10-15 mins later when coming back.

Any ideas on what I might be missing? I have not seen a single drop of gas anywhere on the engine, the tank/lines, or the ground!

2002 Wrangler X with 4.0. Stock.
 
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#2 ·
You are sure none of the injectors has a small external leak resulting in falling rail pressure and a gas smell
, be damn sure as a tiny leak can burn your beast to the ground as fuel fumes are pretty ignite able from 12 volt sparks

I don't understand what an injector o ring has to do with the Evap system as I think you related them in your post


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#4 ·
At this point you need to take it to a GOOD mechanic, he will probably find it pretty fast.
Or you could keep messing around and have a fire.
Just sayin', all you have done with no success seems you need a little more help than opinions. After all we can not see or smell the location from a forum.
Gasoline leaks are nothing to put off lightly,
 
#5 ·
Thanks for the replies guys.

Digger84 -- sorry, that was a little confusing on my part. I tested the evap and fixed some minor leaks. I tested the intake manifold and found a small leak on the manifold side of the an injector. After replacing the O rings, I retested both the manifold and rail side. If there is an injector leak it is something small that I have missed during 3-4 inspections. I'll look again!

H-D dealer dude -- the vast majority of it is metal line. I checked for rust and did replace all the rubber parts.

EarthCruzn -- It goes into the shop next week. I am going to give it one more afternoon of my time this weekend. And your point is well taken. Throughout all of this, I have been just running it in my driveway to test. With a fire extinguisher by my side!
 
#7 ·
Sounds like you understand the risks and have done a fair amount of troubleshooting. The test with soap solution won't really work with liquid leaks, but should show something under air pressure (unless the joint you disconnected to apply air pressure is where the leak was). I would agree that a strong smell of fuel in the cab is more likely coming from the engine bay rather than the fuel tank. The connection between the fuel rail and the fuel line seems like the least reliable joint... best of luck and be sure to post up what the ultimate resolution is.
 
#8 ·
I would also be sure no fuel on outside of injectors from a injector leak or leak at rail to injector o ring

The falling pressure on shut off makes me suspect a leak like that rather than injector to intake which would not affect rail pressure


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