Intermittent Gas Leak???

[helusay]

Hey guys,
I am having some problems and I hope some of you can help me out. This morning I noticed my truck was leaking something when I backed out of my parking spot, so I put my truck in park and hopped out to investigate. Apparently, I have sprouted a gas leak, so I turned and looked at my truck, and noticed that it was sill leaking (at a pretty good rate too). So, I pulled my truck back in and the leak appears to be coming from the right side of the engine compartment, actually there are two one towards the front is the worst and the one towards the back drips about half the rate of the one in front. I was REALLY ticked off because I was dressed for work and not prepared to get under the truck. So, I popped the hood and could see no evidence from the engine bay of a leak from up top. Investigated by the right wheel well as well as I could without getting on the ground, and I did see what looked like some fluid had sprayed from the engine side of the frame, towards the engine, but it was not spraying while I was looking @ it, but that could be a source of one leak, or possibly some future frustration. I got really frustrated and turned off the truck and was going to go inside and call in sick to work, and I remembered it's payday, I have to get my check, plus it's a school night too. I got REALLY frustrated thinking of everything I had to do, and I looked back under the truck, and the leak had stopped. I figured screw it, I HAVE to go to work, and fired the truck back up, and looked for a leak, still nothing. I drove 15 miles in to work eyeballing the gas gauge the entire trip. I got to work and looked under my truck, still no leak. The truck has been parked for an hour, still no sign. Granted, I parked the truck in the part of our lot that is dirt so that any gas would be absorbed, but no sign of discoloration that there would be if something was dripping. Weird.

I recently switched some vacuum hoses that go from the intake plenum to some regulator on the right fender because I thought I had them backwards, and I cleaned my throttle body, but that is about it.

I have always noticed a gas smell that came from the truck when it was cold in the morning and I took off while the engine was still @ a high idle, but I never had a leak before today.

Does anyone know why it would be leaking while cold and stop after warming up? I would think maybe it has to do with my cold start injector, but I would see evidence of that in the engine bay when I popped the hood, wouldn't I?

As always, any help would be appreciated.

Thanks

 

[helusay]

Okay, 3 hours and still no leak spots visible, and no leaks when the truck was started.

 

[the_dingman]

Interesting...

I would recommend not driving the truck until you find the leak. It sounded like you said the fuel had sprayed on the engine, and as such, driving like that does risk that fuel igniting, causing a whole mess of problems...

 

[helusay]

Ok, I took it for a drive just now. Still no leaking. BUT - the engine did sputter a few times while it was cold. After the engine warmed up, it was fine. Is it possible I am having a problem with my fuel filter? Where exactly is it located?
Thanks

 

[the_dingman]

I believe the fuel filter is in the tank.

 

[helusay]

I looked and the filter in the tank is the fuel pump filter. Apparently there is another filter located elsewhere. I think it may be located in the area of the leak. still strange that all my symptoms happen when the truck is cold though.

 

[helusay]

OK. Last night after work, no leaks, no sputters, but the truck was warm, so I expected there wouldn't be. Stopped at the gas station and put in $10 worth, figuring if I needed to take the tank off the next day it would be best to have less gas.

Got under the truck this morning and I could see no sign of where the leak was coming from. Irritating.

So, I switched the two larger vacuum hoses that go to the cluster on the passenger fender back to the way they were. Started up the truck, got out, no sign of the fuel leak at all. Looked in the engine compartment, no sign of a leak, no smell of gas, nothing. Look under the truck, no leak. THIS IS WEIRD!!

I am at my wits end.

Does anyone have any insight on this? Is it possible that 2 crossed vacuum hoses could have been my problem? I never saw the leak before I changed the hoses, and now that I have put them back, there is no leak.

Does this even sound logical?

-Thanks

 

[helusay]

Ok, the leak is back. I replaced the fuel filter yesterday, no leak.

I got in the truck this morning, and got a good smell of gas, looked under the truck, nothing.

Drove the truck down the street, parked it, looked under the truck, fuel leak. Truck was low on gas from changing filter yesterday, put $10 in the tank. Leak stopped after truck warmed up.

So, here are my common symptoms with my leak so far:

Only leaks when in the morning when the truck is cold, and I am under 1/4 tank of fuel.

Also when I am low on fuel is when it appears to run worse/sputter under load.

I went to my mechanic this morning, and he told me he can't find where the leak is coming from.

Please someone help.

-Thanks

 

[fishn808]

I had the same intermittent gas leak problem with my 1990 3.0 4Runner (172K miles). Replaced the fuel injectors (all) and a fuel rail fitting at the rear of the fuel rails and the problem was solved. The fuel injectors would leak when the engine ran hot (heavy traffic on hot muggy days) or when started on really cold days. My mechanic said this was not uncommon - caused by old, hardened O-rings on the injector seals. Similarly, the fuel rail fitting at the end of the fuel rail has an O-ring that failed when exposed to extreme temperatures. My mechanic also advised me not to drive the vehicle if this happens ever again or risk a fire and lose the entire vehicle.

 

[fourwd1]

I second the leaky injector theory, although I've never heard of them leaking bad enough to cause puddles.
You can get the O-rings from the dealer and replace them instead of the whole injector.

 

[n8buddy]

i just went through hell with a gas leak, which was started by a brake line rubbing on the fuel line, eventually wearing a significant hole in the gas line. the hose is located on the right side (driver side) of the charcoal canister. It sat in the shop for 5 weeks b/c they could not find where the hose went, eventually they had to take the top of the motor apart b/c the line goes behind the motor. Also it was a special order part, of course. anyway the gas would leak down the passenger wheel well, so check there to make sure you dont have this problem.