I have noticed in some cars that there is some pressure that builds in fuel tanks, but mine is very excessive, like when I open the cap a lot of air is released for a couple seconds. Is this normal, the guy I bought it from said the check engine light used to come on but the code was something for the fuel cap? I also smell gas in the car periodically I thought I might have a hole in the tank but thats not possible or else there wouldnt be pressure buildup. and i havn't noticed any leaks. Any help would be appreciated.

 

I have a 98 GMC Sierra that does the same thing as far as the pressure goes, I've never had an issue with fuel vapors in the cab area, and it's done this for the past four or so years that I've owned it, and even makes the tank go bonk, like a soda pop bottle, with changes in pressure. I don't think the pressure is an issue but you've got to be leaking feul somewhere if your smelling it. I'd take a moment and follow the fuel rail to see if you can find any wet spots, check the top of the intake, and the air intake lines from the filter box for fuel pooling. Does it do it when you top off the tank? Maybe it's leaking out the filler tube somehow?

 

Vehicle information? Any stored codes?

 

hey dj

I had the same problem in my 4-door 97 blazer. same codes for leaking
fuel cap replace it same problem. smell of gas plus the high pressure in
the tank. would stall the vehicle on hot days. took it to the shop turns
out to be the vent value on top of the tank. i drop the tank to replace
the fuel pump snap it off didn't even notice. a replacement tank later
no issue. no smell. no high pressure. no stalling not saying this is your
problem but if that tank was drop a good place to start

 

Check your charcoal cannester could be full of fuel and not venting. Aso you should have a cannister purge valve that will suck the vapor out and into the motor. That could be stuck/broken and allowing excessive pressure to build up.

There is definately something wrong with the vapor management system, depending on where you live it could cause a fail at inspection time!

Like Kyle said it helps alot for us to have the year/engine/dtc's and mods/recient "fixes"

 

its a 97 4x4 2 dr sorry it took me awhile to get back to this thread, I will update back when I take it to the shop but I cant get it there to soon, so any other ideas for me would be great! Thanks guys.

 

Well guys I know this is an old thread but still having the problem update:

I removed charcoal cannister and inspected it, looked good wasnt full of fuel, I blew into the big line that goes to the purge valve and it came out one of the fuel lines, so doesnt seem to be blocked up, I didnt blow into the other hole though that the fuel line connects to... I also disconnected both the evap purge solenoid and vent solenoid put 12v + and - on it and they both worked, I didnt check while on the truck so maybe a wiring problem? I dont know what else to check, I havent gotten the gas smell all winter or this spring but still have the p0440 code I was going to have it smoked but if there was a leak wouldnt i have a leak code instead? Only thing I havnt check is the fuel tank pressure sensor but if that didnt work the fuel tank would malfunction right?

I get poor gas mileage and a very slight misfire at idle. Any ideas? How about the evap test port do I put vaccum or pressure on that and what am I looking for? Any ideas are appreciated!!!!

Could it be something with the fuel tank filler neck? It has a slight kink in it but now much and fills fine is also kind of rusted.... any help would be appreciated!

One more thing when the tabs on the fuel pump module are pointing towards you the 2 on the right are kinked but fuel is still getting through I also am overdue for a fuel filter but cant get it off so will have to go in soon can this effect anything? And anyone know the order of the lines and wat each one is for? Thanks a lot guys! this is really starting to **** me off
I am open to all suggestions!

 

Help!

 

You have so many problem threads that I am having a problem keeping them all straight... Maybe all of the problems have a common cause..? I can say that I don't really have the time to pull all of your information together to root it all out. Good luck with it though.

 

This is the only engine problem I have with my truck! I cant afford to buy another one or bring it to a shop, I just had a kid as you may already know and I really cant have my truck break down... Thanks though maybe someone can chime in, just trying to be thorough I am going to replace the fuel lines in the next couple days and try that... But I dont think it will stop the problem...