Gas exploded in my face from fill hole!!

So something strange happened to me today. It was pretty aweful, and I have never heard of it happening, so I thought Id ask if this was just a freak thing or if others have encountered it...

I went wheeling with a friend, and we were about an hour into the trip when we stopped for a bit at the end of a road. I filled up my gas tank right before we left, probably had driven 50 miles by that point.

As we are chatting, we notice the sound of air leaking somewhere on my jeep (1991 XJ). We thought it may have been a tire losing air, so we were trying to pinpoint it. I randomly decided I should let any extra air out of the gas tank to eliminate that as a source of the air leak. I guess I thought of this because of all the air that usually comes pouring out (especially in summer) when you take the cap off to fill up.

So i start unscrewing the fill cap, not thinking anything of it....then BAM! A good 2 gallons + of hot gas comes shooting out of the fill hole with some serious force, hitting me in the face, eyes, mouth, and most of the rest of my body.

So what the hell? I was on a hill, with the front of the jeep facing downward. all we could come up with was the air in the tank expanded (it was 105F + today) and somehow I was in a position the air couldnt get out of the fill hole without pushing gas out first?

I must say, it was all up in my eyes and contacts, and no part of me was gas-free enough to get them out, plus I cant see without them. So ended up spending the next 8 hours of wheeling mostly clothe-less and pouring eyedrops in my eyes. It was a totally cool trip, so it made up for it...

Anyone ever experience this? Does that explaination make sense?

Ben

let me ask you this. where is your tailpipe.

I had this happen to me in my first car..

Story time:

first car, 87 celica. i had decided to be cool and take off the axle-back portion of the exhaust, while not realizing it this was dangerous, the exit of my exhaust was now pointing somewhat too my fuel tank, and my brakes.

on the test drive "To hear how cool it would sound" I lost brake pressure, 3 weeks after this stunt, i was still running it the same way, having to pump the brakes, could not figure out why. then my gas tank got extremely hot (on a 100* day) and i released the pressure at a gas station, only to have fuel spew out.

2 days later i put a new exhaust system on the car, to find my fuel tank Charred, coated black all on one side..

the minute i put the new exhaust on, all systems were back to normal.

something is heating up the tank. its not a "Normal" thing for fuel to expand so rapidly. even with high weather temps.

That makes sense, or your XJ is suffering from bulimia!

Your evap system made need servicing.

VERY interesting! I do have an exhaust leak I have been hearing since my last wheeling trip. I will go check that out tomorrow. Thanks for the tip!!

Ben

nw-xj-scott said:

let me ask you this. where is your tailpipe.

I had this happen to me in my first car..

Story time:

first car, 87 celica. i had decided to be cool and take off the axle-back portion of the exhaust, while not realizing it this was dangerous, the exit of my exhaust was now pointing somewhat too my fuel tank, and my brakes.

on the test drive "To hear how cool it would sound" I lost brake pressure, 3 weeks after this stunt, i was still running it the same way, having to pump the brakes, could not figure out why. then my gas tank got extremely hot (on a 100* day) and i released the pressure at a gas station, only to have fuel spew out.

2 days later i put a new exhaust system on the car, to find my fuel tank Charred, coated black all on one side..

the minute i put the new exhaust on, all systems were back to normal.

something is heating up the tank. its not a "Normal" thing for fuel to expand so rapidly. even with high weather temps.

Click to expand...

I was thinking that too. Isnt the evap canister under the hood there to let the air escape? I mean, to avoid this very situation?

Ben

joe_peters said:

That makes sense, or your XJ is suffering from bulimia!

Your evap system made need servicing.

Click to expand...

pantherchams said:

I was thinking that too. Isnt the evap canister under the hood there to let the air escape? I mean, to avoid this very situation?

Ben

Click to expand...

Not escape, it goes through the purge valve and into the engine, but yes it is supposed to "vent" fuel vapors.

Thought this might be of interest to you:

http://www.stant.com/brochure.cfm?brochure=201&location_id=170

joe_peters said:

Not escape, it goes through the purge valve and into the engine, but yes it is supposed to "vent" fuel vapors.

Click to expand...

Oh, really? Do you know at what point it enters the engine? Im just wondering how that works with maintaining A/F ratios. I didn't know it worked like that.

Thanks for that cap too! If i cant figure out what went wrong, i will be getting that. I could go for that NEVER happening again!

Ben

I think the purge valve is supposed to be constantly operating, and the O2 sensor and ECU should be able to handle it--really is vapors.

Internet says (always consider the source, especially me!) that something like 22 gallons of gas, or 170 something pounds of gas vapors are lost annually from a vehicle with bad gas cap and/or evaporative emissions equipment.

When my exhaust manifold was cracked, I noticed that my gas tank built up a lot of pressure. I installed a Borla header, because of their guarantee and the fact I had had two stock-type manifolds crack under severe service. I wrapped the header with fiberglass belting, sold for the purpose at a hot rod shop, to get the exhaust heat back a little farther. Then, pulling a camping trailer up a long steep hill (4000 RPM in 2nd gear) the rear floor carpets started to smoke. I wetted the carpets well enough to finish the hill, but when I got home again I wrapped the rest of the exhaust system with the fiberglass insulation. I don't have any more problems with the exhaust or the fuel system.
I would also check the charcoal cannister and the tubing from the tank to it.

Somewhere back in the long ago (~1970?) some idiots worried about them vapors getting out into the air. So they got laws passed, that end up requiring a POSITIVE pressure in the gas tank. (about a 1/2 lb psi or so.)

So since then, if the fuel system springs a leak by the engine and it catches fire- that Positive Pressure feeds Fuel to the fire!!! Thats probably why so many cars started showing up along the side of the road front end totally burned up. (instead of just broken down!) And Fueling accidents happen more often.

The 'proper' way to open the gas cap is to -crack it 1/4 turn or so, Pause and let that pressure drain off,(few seconds) -then remove the cap. Gas sloshing around inside can get into the vents and filler piping. BE CAREFUL.
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Glad the OP did OK!
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If someone gets 'soaked' do NOT get near vehicles till dried off. Even the ign and light switches spark are enough to trip a disaster.
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(Oops-Sorry for lecture!!...'don't ask me how I really feel about it!!')

Good Luck and Best Regards,
O

WAIT.

do you have a flowmaster muffler?

And don't smoke!

When I bought my jeep the previous owner decided to cap the vent line from the gas tank to keep water out. So when the tank was empty it had a vacuum on it. Then when I opened it up to fill it the rush of air would cause gas to rush out of the tank on to me as you described.

very interesting. ive pumped gas on and off (jersey full serve) for almost 6 years through highschool and summers and thats thankfully only slightly happened to me once or twice. only about a 1/4 gallon came out each time though. let me tell ya though that on hot days some caps on older cars would have tons of vapor pressure behind them and would 'hiss' for a solid 5 seconds sometimes. nothing as intense as what the OP experienced.

id have to say though that im much more worried about occupied wasp nests inside gas doors than excessive pressure haha. ive had to back away from many wasp contaminated gas caps while the driver of the car gives the 'why did you stop pumping my gas look'

cphillips said:

very interesting. ive pumped gas on and off (jersey full serve) for almost 6 years through highschool and summers and thats thankfully only slightly happened to me once or twice. only about a 1/4 gallon came out each time though. let me tell ya though that on hot days some caps on older cars would have tons of vapor pressure behind them and would 'hiss' for a solid 5 seconds sometimes. nothing as intense as what the OP experienced.

Click to expand...

x2. oregon is full service aswell. and i have never dealt with this on anybodys vehicle, but my own.