gas tank questions
 

something very strange, or maybe not so strange, happened to be the other day. i went down into colorado springs to pick up a fuel pump for my girlfriends s10, on my way up i stopped at a gas station and put a gallon or 2 to ensure that i would have enough to make it to my favorite gas station where i would fill up the tank. when i took the gas cap off, gas started spewing everywhere! and it wasnt just a quick spew, it was a rushing of air for probably 10 seconds or so with a mixture of gas coming out. it was enough to get me, make a little puddle mark on the ground and to run down the side of the car. i have never had this happen before and im wondering if something is going wrong. to ad to the confusion, when i finally made it to my gas station, i went to fill it up and i could only get about 10 cents in gas at a time because the gas pump kept shutting off as if the tank where full. i ended up having to back the filler out of the tank, and slowly filling the gas to keep it flowing. i only put 20 bucks in also because it took so long. i have not put more gas in or removed the gas cap since then, but could this be an indication of a problem? maybe a fuel filter being so clogged that the fuel pump is building up too much pressure or something?

i might also mention that it was very hot that day, in the 90's according to the svx, and i started at about 9k feet, drove down to about 7k feet (whatever colorado springs is at, im not for sure on that) then back up to 9k feet where i took the cap off the refill for the first time when it spewed. this was all within probably an hour or an hour and a half.

Re: gas tank questions
 

Never experienced anything like this. Some times when I remove the gas cap there is air pressure that blows out, no gas. When I was a kid, mid 50's the family had a 55 Chevy wagon, on a trip pulling a camp trailer at elevation (7000+) the car stopped running, it had a vapor lock. That's what I thought of reading your post.

I'm hopeful a tech will explain this for you.

Re: gas tank questions
 

Vapor lock is when not enough air can get into the tank as per the fuel leaving it. Thus causing a severe vacuum in the tank... This is quite the opposite... No reason for the tank to spit fuel unless it was already overfilled and over heated. Only thing that would do that is excess fuel pressure applied to the tank or a vent blockage... Keep an eye on it and let us know if it happens again

Tom

Re: gas tank questions
 

Sorry, my wild guess........

Re: gas tank questions
 

We have a guy with a Suzuki Sidekick that comes to the shop about once a year. The tank vent gets clogged and he can't put gas into the car. In his case the vent is in a horrible position that gets full of dirt and crud.

Re: gas tank questions
 

it sounds like you have ether a issue with your evaporate emissions system or your your fuel pressure regulator.. you should check fuel pressure and flow (i don't think there is a spec for flow if you need i can look up a general one) and check codes as well even if the check engine light is not on.

and to clarify vapor lock is when the fuel heats up in the lines around the engine enough to turn it to vapor causing the car to stall because the fuel pump cant pump air.. its alot more common on old cars due to the fact that fuel pressure was like 5 p.s.i not 30+ like todays.

Re: gas tank questions
 

My vapor lock was in the late 40's in Texas.
It would happen on a hot day, in Texas?,:D and the reason was a gas line too close to the exhaust manifold... creating a vapor on the fuel line and would not let the engine run... no fuel to the carberator.

I was 18 and it was my first car!
took it to the shop for repair.

Since I ran the battery down trying to start it, It needed a new battery! They put one on.

.Next vapor lock, took it back to the shop for repair must be the alternator causing the battery not to stay charged? They put one on.

Next was the starter. took it back to the shop for repair Bad starter was running the battery down so... They put one on.

took it back to the shop for repair... had to be the carberator... they put one on.

I told my uncle my dilemma, and he said, "you just have a vapor lock"! He showed me how to re-rout the line and I was Home free!

As home free as a person can be that has been taken to the cleaners by a repair shop.

Many things have changed the last 60 years, but the guessing business still remains intact.

that was 60 years ago that I promised myself that this would never happen to me again, and I have pretty much kept that promise.

I would not refer to a negative pressure in a gas tank as a vapor lock. I am with you dromano on this one! Tom is way to young to know this.:lol:

A vapor lock would be vapor in the fuel supply line instead of fuel.

Keith:)

Re: gas tank questions
 

thanks for all the input everyone! i think i know my way around cars pretty well, i had a fuel pump go out in an s10 a few days ago, no one believed me that it was the fuel pump because "im only 18 and no mechanic" im told. took it to a shop, charged 50 bucks to have them tell us it was the fuel pump! ha, i knew it the whole time, i woulda bet money on it! they wanted 400 for the part and 250 in labor, we got the part for 250 and i put it in myself. im no mechanic, but i think i can handle myself lol. just finished up that yesterday and the truck is running great.

anyway, my car usually has the vacuum and sucks in air or blows it out, im not really sure which because i dont try to feel it. i guess it blows out since the gas blew out. i know my fuel tank wasnt overfilled because i had only about a 1/4 of a tank the day before, i put $20 in at $4.09, and i had driven on that much gas for about 60 miles or so. i just got home also from driving a few miles and i opened the gas cap, all that happened was a little vacuum air, nothing much, just the normal thing that usually happens. i havent put any gas in since that day though, so ill see if anything is different then.

could this possibly be caused by a clogged fuel filter? ive been wanting to change that for awhile, but just never have gotten around to it. ill probably do that whether or not anyone thinks it could be that just because i dont know when its been changed. also, the car runs just fine, it doesnt feel any different or anything, no power lose, no stuttering or hard starting. it seems just fine if that helps. i just hope i dont have to drop the fuel tank in this, it looks like it might be a little harder than the s10 was.

maybe this was just a fluke from the heat, that was the hottest day of the year so far and i was driving up a pass, so the car was probably hot from that too. not sure though, maybe its not a fluke?

Re: gas tank questions
 

When I worked in gas stations in the early 60's the approach to engine repairs was exactly as you describe all the parts that were replaced. We just kept installing new parts till engine ran normal. Some times it would take one part, some times many.

By the way, I don't think there were any alternators around in the 40's, remember generators and voltage regulators? Installed many of those.:D

Re: gas tank questions
 

Sorry was in a rush. (little different when a person hasn't typed in half a century). :lol:

Of course it was generators back then... And I forgot about the fuel pump replacement as well.

Heck, if it had been 15 years later, I would think it might have been at your station!

Keith:)

Re: gas tank questions
 

Good for you!!!

Keith:)

Re: gas tank questions
 

I deal with it on the bikes now... Not like carbs are not used on anything anymore. I guess you can use the word for different things but we have always used vapor lock considering the vapors are "locked in" and not allowing the tank to drain anything out...

Tom

Re: gas tank questions
 

X13, there are two things that may cure this problem for you.

First thing, as it fired out gasoline when you opened the filler cap, this implies your fuel tank is building up pressure. This can be caused by a blocked or bent vent pipe, and you need to check this.

As you probably know, when fuel feeds down to your tank via the filler neck, there is a smaller pipe returning from the tank which allows the air in the tank to leave as the fuel is spilling in.

My guess is the vent pipe in yours is blocked for some reason.

There is also a check valve at the bottom of the filler pipe close to the tank. This might create the problem you have, but I doubt it. I think your vent pipe is blocked.

Joe

Re: gas tank questions
 

I have experienced this very same issue with a certain 92 Ebony LS-L which I drove for a month or so. The owner of the car knew it was an issue and during the time I drove it, my preliminary investigation yielded the solution to the problem.

The tank had been under excessive pressure after the car had shut off, due to a vacuum line for what I believe was for the FPR (Fuel Pressure Regulator) becoming disconnected from the intake manifold.

I do have to go out and check, but I believe this line is located at the passenger rear of the manifold and is very small in diameter, making is susceptible to breakage, clogs, or, as in my case, it had simply become disconnected.

I hope your problem can be fixed in a similarly simple fashion. :)

Re: gas tank questions
 

sense no one listened to me the first time let me repeat my self and fully agree with mike 621

it sounds like you have ether a issue with your evaporate emissions system or your your fuel pressure regulator.. you should check fuel pressure and flow (i don't think there is a spec for flow if you need i can look up a general one) and check codes as well even if the check engine light is not on.

and to clarify vapor lock is when the fuel heats up in the lines around the engine enough to turn it to vapor causing the car to stall because the fuel pump cant pump air.. its a lot more common on old cars due to the fact that fuel pressure was like 5 p.s.i not 30+ like todays.