A LOT of excess pressure in the fuel tank

[GSXV8Killa]

I am getting a lot of excess pressure building up in my tank and the car runs different whether my gas cap is on or off. Running a single 255. Im assuming a valve or solenoid has gone bad? Thanks for any feedback

 

[hondo0975]

I looked at your list of mods an didn't see any posted so I'm not sure what all you have done to your car. If you have done the evap delete an cut your vent line that runs to the charcoal canister, an then plugged that line off, that could cause this. The proper way is to attach a piece of vacuum hose after check valve an run that line out the bottom of the car behind the engin bay. If your stock gas cap has been switched out with an after market cap,, you should get a oem cap back on there. There is a vent on the fill neck of the gas tank that could also be plugged but, not likely from what I have read. A quick fix I read some people do is to drill a small hole in there gas cap. Just make sure that what ever you do before you remove your gas cap touch something stainless steel. I always touch the stainless steel on the gas pump, an no not next to the pump its self but there is usually plenty of stainless steel on a pump some where. This will remove any static electricity that has built up in your body. I highly recommend you figured this out quick. I even read one post that suggested its possible to blow up your gas tank from building to much pressure. So Ya at least drill the hole in the cap if you have to use this car as a daily driver. They did not say how big of a hole, but I would think 1/8 inch or just a little bigger ought to do. Good luck hope the best for you.

 

[GSXV8Killa]

Okay that helps some. All stock emissions are still on the car. Forgot to include that sorry.

 

[hondo0975]

Any updates?

 

[GSXV8Killa]

Gas cap appears to be stock and with the amount of pressure I'm seeing I highly doubt a small hole in the cap would help. No lines appear to be kinked or blocked to the canister. Isnt there a vent tube somewhere? On the filler neck or tank somewhere?

 

[hondo0975]

Yes there is a vent on the filler neck. As I understand it this vent is for the function of filling the tank an only serves to releave pressure while filling the gas tank. Have you looked in your repair manual for gas tank vent lines. I'm not at home or I would look for you. My suggestion is to start there an find other where all vent lines are. Looking around on the internet could not find definite answer but I'm sure there's at least two an some people say three. Fill neck vent an vent line that runs to the charcoal canister. I'll look in my manual for vent lines when I get home. Does it suck air in when removing the cap or blow air out of it?

 

[GSXV8Killa]

Its blowing air out

 

[hondo0975]

Well I have been going over my manual an searching the internet for the last couple of hours. You have a purge control valve an a purge control solenoid valve. One of the two is likely bad. Not sure if you have a vacuum gage to test the purge control valve, if so Google it to see how to do it. Basically you apply vacuum to the bottom nipple an then you should be able to blow through it very easily. It's also shows you in your manual. From what I read it's likely your purge control valve. An as for drilling a hole in your gas cap, you have to drill from the back side of the cap an don't go all the way through, just drill through the first piece of plastic on back side. You could probably go to autozone or Napa an remove the purge control valve in the parking lot an ask them to test it for you right there. Although that would only confirm if it was bad. I called autozone to price one of these for you an they do not carry that part. Not sure if Napa does or not they were already closed before I could call them. Hell you could even go to a dealer an remove it there an have them check it also. Just make sure that if you do take the car some where to have the purge control valve tested, that you take your gas cap off first. This will releave the pressure so you won't have gas fumes expelled in your engin bay. This is just some info I came up with searching around. I would spend some time looking around yourself an you will have probably come across the same threads I've been reading. If you get this figured out let me know what it was please. Good luck.

 

[GSXV8Killa]

Well I have been going over my manual an searching the internet for the last couple of hours. You have a purge control valve an a purge control solenoid valve. One of the two is likely bad. Not sure if you have a vacuum gage to test the purge control valve, if so Google it to see how to do it. Basically you apply vacuum to the bottom nipple an then you should be able to blow through it very easily. It's also shows you in your manual. From what I read it's likely your purge control valve. An as for drilling a hole in your gas cap, you have to drill from the back side of the cap an don't go all the way through, just drill through the first piece of plastic on back side. You could probably go to autozone or Napa an remove the purge control valve in the parking lot an ask them to test it for you right there. Although that would only confirm if it was bad. I called autozone to price one of these for you an they do not carry that part. Not sure if Napa does or not they were already closed before I could call them. Hell you could even go to a dealer an remove it there an have them check it also. Just make sure that if you do take the car some where to have the purge control valve tested, that you take your gas cap off first. This will releave the pressure so you won't have gas fumes expelled in your engin bay. This is just some info I came up with searching around. I would spend some time looking around yourself an you will have probably come across the same threads I've been reading. If you get this figured out let me know what it was please. Good luck.

Thank you very much for you devoted time and research. I thought that my purge solenoid was bad from the little research I did but I wasnt sure how to test it. I will definitely try this out and tell you my results. I also priced them out and cheapest I could find online was $70. I havent tried any of the local parts stores but if after testing it, its bad I will definitely be pricing one out local first. I checked my lines going to the canister and they all see to be free of kinks and blockage.

 

[Colt4G63 also]

Check the canister vent valve, and don't drill any holes unless you want to have a code P0440 and fail inspection.

 

[hondo0975]

Thank you very much for you devoted time and research. I thought that my purge solenoid was bad from the little research I did but I wasnt sure how to test it. I will definitely try this out and tell you my results. I also priced them out and cheapest I could find online was $70. I havent tried any of the local parts stores but if after testing it, its bad I will definitely be pricing one out local first. I checked my lines going to the canister and they all see to be free of kinks and blockage.

Your welcome. The test I was referring to earlier was for the purge control valve located next to the charcoal can ( at least on my 92 1g). Not for the purge control solenoid. I know yours is a 96 an I'm not sure if the test is done identical to the way I would test mine, but this is how I test mine. Here is what my manual says for testing the purge control solenoid.

1. Disconnect the vacuum hoses from the purge solenoid.
2. Disconnect the electrical connector from the purge solenoid.
3. Connect a hand held vacuum pump to the port with the red striped vacuum line an apply vacuum.
4. Use jumper wires an apply battery voltage to the solenoid. When the solenoid is energized, the vacuum should leak down (purges). When no voltage is applied the vacuum should hold steady.
5. Also, measure the resistance of the purge solenoid (ohms meter reader). It should read 36 to 44 ohms.
6. If the test results are incorrect replace the solenoid with a new one.

Here's a link that also has some really good information worth checking out.
OBD-II Trouble Code: P0443 Evaporative Emission Control System Purge Control Valve Circuit

 

[Colt4G63 also]

They move these things around from model to model, but if your canister is in the front bumper, the shut valve is here:

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This valve should open when you shut the car off, and relieve any pressure in the tank.

 

[hondo0975]

Any updates?

 

[hondo0975]

Did you ever get this fixed?

 

[GSXV8Killa]

Yes, thank you. The vent tube to the canister was kinked