Gas Station Filling Issue - Fourth Generation Pontiac Firebird (1993 - 2002) - Firebird Nation

Jump to content


FirebirdNation.com is the premier Pontiac Firebird forum on the internet. Supporting Members do not see the above ads.
Photo
- - - - -

Gas Station Filling Issue

Filling Shut Off Stops Filler

  • Please log in to reply
11 replies to this topic

#1 nyan

nyan

    Firebird Newbie

  • New Member
  • Pip
  • 5 posts
  • Gender:Male
  • First Name:don
  • City:asheville
  • State or Province:NC
  • Country:USA
  • Year: 2000
  • Make: pontiac
  • Model: firebird
  • Engine: 3800
  • Transmission: 5 speed

Posted A week ago

Hello all,

When putting gas in the tank of our 2000 3.8 V6 car we have to do so VERY slowly or the gas pump will shut off as it would if you had a full tank of fuel. Do not know the history of this vehicle other than the previous owner did let us know about this issue before we purchased it a few months ago. I assumed it had a stuck closed/blocked vent valve as it has a P0446 DTC stored.

 

Removed the fuel tank today and started to do some tests. I was able to blow freely through the vent valve so I assume that the vent valve is okay. Then loosely sealed an air nozzle set at 5psi to the filler opening of the tank and slowly pulled the trigger. The tank started to expand and some air started to come out of the hose that goes to the vent valve from the charcoal canister. Next I disconnected the canister from the tank and did the same test. This time the tank only very slightly expanded and more air came out of the hose that was once connected to the canister than in the last test.  I am assuming that I have a plugged up charcoal canister but also worried that there also may be a restriction or issue also in the (valve?) that is molded to the top of the tank as it does not quickly vent out the rather small amount of air that I am putting in. Or maybe that is normal result? Any thoughts or better ways of testing for this gas filling issue would be appreciated.

 

The canister feels very heavy to me and will expand and make noises when I barely put any amount of air to it by itself. I am thinking that the canister needs replaced. If that is the case, it makes me wonder about why it blocked up in the first place. Have not checked the purge solenoid operation yet...maybe there is no purge flow thru the canister? Could that cause it? Maybe something else? Again, any thoughts would be appreciated. Hopefully I am on the right track to solve this problem. Thanks in advance for any help!!  Oh, BTW found the roll-over valve laying at the bottom of the tank....suspect the prev. owner decided to try and knock it thru the tank to try and fix this issue lol! I don't blame him for trying...the tanks don't come out of these too easily.



#2 Injuneer

Injuneer

    Just Trying to Help

  • Administrator
  • 14126 posts
  • Gender:Male
  • First Name:Fred
  • City:Central NJ
  • State or Province:NJ
  • Country:USA
  • Interests:Licensed Professional Engineer (Mechanical)
  • Year: 1994
  • Make: Pontiac
  • Model: Firebird Formula
  • Engine: 381ci LT1 stroker
  • Transmission: TH400 + GV O/D

Posted A week ago

There's an over pressure relief valve on the tank, and a vent on the tank.  The discharge lines from both those tee together and go into the carbon canister.  A plugged canister would definitely limit tank venting.  
 

I only know the because I helped someone on another site who installed the plastic tank from a 2000 3.8L into his 1997 Camaro, replacing the slightly smaller metal tank used 1993-1998.  He experienced problems filling the tank, and we chased down how to increase the very slow fuel fill rate. While his eventual “fix” was not directly related to your situation (he was keeping the 97’s outboard canister, and did not need the vent solenoid), the labeled photo might prove useful.

 

https://www.camaroz2...k-886314/page2/

 

P0442 is for a small vacuum leak when the PCM closes the vent solenoid, opens the purge solenoid, then pulls a vacuum on the system.  When the vacuum test value is reached, the purge solenoid is closed, and the PCM measures the vacuum loss vs. time to determine if there is a small leak.  A leak in the line from the canister to the purge solenoid would limit the ability of purging the canister, possibly allowing it to be saturated with fuel = heavy and plugged.  Just a possibility.


1994 FIREBIRD FORMULA
FRED

 
381ci all-forged stroker (Callies Stealth, Oliver billet rods, BME 2618-T61 nitrous pistons) - 10.8:1 - CNC LT4 heads/intake - Comp Cams solid roller - MoTeC M48 Pro engine management - 8 LS1 coils - 58mm TB - 74#/HR injectors - 300-shot dry nitrous - TH400 - Gear Vendors 0.78:1 O/D - Strange 12-bolt - 4.11 Pro-Street gears - AS&M headers - true duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP / 800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117 MPH straight motor
 
https://www.firebird...9_698_32777.jpg

 


#3 nyan

nyan

    Firebird Newbie

  • New Member
  • Pip
  • 5 posts
  • Gender:Male
  • First Name:don
  • City:asheville
  • State or Province:NC
  • Country:USA
  • Year: 2000
  • Make: pontiac
  • Model: firebird
  • Engine: 3800
  • Transmission: 5 speed

Posted A week ago

Thanks Injuneer. The pic that you linked looks just like our gas tank and the black colored molded-in-tank valve marked as part of the vent system is the one that has me confused as it does seem a little bit restrictive when "testing" the system in the way that I am. But it may be a normal result as I am pretty sure that I am putting in more "test air" than an actual refueling event would ever move or displace?

 

You bring up a good point about a possible leak on the purge side of things as the prev. owner said the shop cleared the codes after they were done looking at it right before he was getting ready to sell it. So, maybe the evap system has not had a chance to look for a leak in a while possibly because the vent valve code sets first and stops the on-board leak check before it ever gets a chance to start?  I'll try to make my own leak test up on the purge side maybe using a mity-vac and see if anything shows up before it gets put back together.



#4 Injuneer

Injuneer

    Just Trying to Help

  • Administrator
  • 14126 posts
  • Gender:Male
  • First Name:Fred
  • City:Central NJ
  • State or Province:NJ
  • Country:USA
  • Interests:Licensed Professional Engineer (Mechanical)
  • Year: 1994
  • Make: Pontiac
  • Model: Firebird Formula
  • Engine: 381ci LT1 stroker
  • Transmission: TH400 + GV O/D

Posted A week ago

My comments on P0442 weren't very helpful.  I should have addressed P0446 - sorry about that.  I should have waited until morning rather than posting at 2:00am.

 

In that respect, your analysis is correct.  Appears you have used the factory service manual, and aware of the other possible causes beyond the stuck closed vent solenoid, including a pinched hose and a plugged canister.  A plugged canister or closed vent solenoid should be easy to detect by trying to pass air through each.



#5 Papa Tango

Papa Tango

    Firebird Tire Changer

  • Full Member
  • PipPip
  • 98 posts
  • Gender:Male
  • First Name:Pete
  • City:Tucson
  • State or Province:AZ
  • Country:USA
  • Interests:Aviation; Hiking; Camping
  • Year: 2002
  • Make: Pontiac
  • Model: Firebird Coupe
  • Engine: 3.8L V6
  • Transmission: Automatic 4LE

Posted A week ago

Don,

Welcome to FBN!

 

On my '96 T/A, I had to change my charcoal canister because of particles of carbon keeping the purge solenoid valve open. As I was troubleshooting the system, I found ALL the rubber hoses hard and cracking. I just replaced ALL the vent and fuel rubber hoses to eliminate a leak problem in the future. There are rubber hoses connecting the plastic lines just Forward of the rear axle and under the drivers seat floor pan. Also, the rubber hoses connecting the vent valves, charcoal canister and purge solenoid valve. 

 

I disconnected the purge lines and blew them out. Twice! The first time after changing the purge solenoid valve. The second time after changing the charcoal canister. Lol

 

Just a suggestion. Pete :)



#6 nyan

nyan

    Firebird Newbie

  • New Member
  • Pip
  • 5 posts
  • Gender:Male
  • First Name:don
  • City:asheville
  • State or Province:NC
  • Country:USA
  • Year: 2000
  • Make: pontiac
  • Model: firebird
  • Engine: 3800
  • Transmission: 5 speed

Posted A week ago

@ Injuneer. What you said about the possible leak / P0442 was good info! Was not considering the way the system might stop the diagnostics before leak checking was complete until you mentioned that. Can't seem to find a valid way to test that black valve in the tank The purge side line from canister to purge sol. holds vacuum so I am assuming no leak. Did not try any testing of the purge solenoid itself as of yet.

 

@Papa Tango, When I go back out there again I am going to do as you suggest. Did not think about debris from the canister either.

 

Thank you both!

 

Thinking of replacing the canister (suspect blocked)  / vent and purge valves (cheap parts-even from GM!) / and fuel tank (Roll-over valve laying on the bottom of tank!?! and mystery(To me) black-molded-valve testing. If I get another tank I will repeat the "tests" from my first post and give the results.



#7 Injuneer

Injuneer

    Just Trying to Help

  • Administrator
  • 14126 posts
  • Gender:Male
  • First Name:Fred
  • City:Central NJ
  • State or Province:NJ
  • Country:USA
  • Interests:Licensed Professional Engineer (Mechanical)
  • Year: 1994
  • Make: Pontiac
  • Model: Firebird Formula
  • Engine: 381ci LT1 stroker
  • Transmission: TH400 + GV O/D

Posted A week ago

One thought for future reference in response to the ability of the system to pull adequate vacuum to meet the diagnostic requirement of P0442 - if the system can’t develop enough vacuum to meet the P0442 (small leak) requirement, it will set P0440 for a large leak.

 

 



#8 nyan

nyan

    Firebird Newbie

  • New Member
  • Pip
  • 5 posts
  • Gender:Male
  • First Name:don
  • City:asheville
  • State or Province:NC
  • Country:USA
  • Year: 2000
  • Make: pontiac
  • Model: firebird
  • Engine: 3800
  • Transmission: 5 speed

Posted A week ago

 

One thought for future reference in response to the ability of the system to pull adequate vacuum to meet the diagnostic requirement of P0442 - if the system can’t develop enough vacuum to meet the P0442 (small leak) requirement, it will set P0440 for a large leak.

 

Thanks for that info Injuneer. I'm really hoping there is no leak but it is possible for sure....Maybe just maybe the prev. owner hurt the canister because he might have been one of those people that would keep clicking the gas nozzle after the tank was full or filling while the engine was running? Fingers crossed.  Wishing now that I had tried to do a thorough evap check instead of just taking the car apart and assuming a $30 part would fix this problem.

 

Got another fuel tank that came complete and did the same test as in the first post.  So, at 5psi with full blast on an air nozzle that was sealed on the tank filler inlet, the air just came right out of the vent valve with no noticeable tank expansion.  Cranked up the pressure to 10psi at full bore with the same result so it looks like the canister is plugged and most likely some restriction in the black molded-in-tank-(valve?) thing as well.



#9 Injuneer

Injuneer

    Just Trying to Help

  • Administrator
  • 14126 posts
  • Gender:Male
  • First Name:Fred
  • City:Central NJ
  • State or Province:NJ
  • Country:USA
  • Interests:Licensed Professional Engineer (Mechanical)
  • Year: 1994
  • Make: Pontiac
  • Model: Firebird Formula
  • Engine: 381ci LT1 stroker
  • Transmission: TH400 + GV O/D

Posted A week ago

In the factory service manual, the black "vent valve" appears to be referenced as the "Fill Limiter Vent Valve" (Volume 2 of 3, Part 2 of 2, Page 6-1263).  But I can't find any specs that define how it operates.  Interesting name though.  Appears easy to remove via a snap ring.

 

I would also be careful with pressuring the tank.  In the metal tanks, the pressure relief valve is set to open at 1 PSI.



#10 GaryDoug

GaryDoug

    Ramblin' Wreck

  • Full Member
  • PipPipPipPipPipPipPip
  • 5049 posts
  • Gender:Male
  • First Name:Gary
  • City:Tarpon Springs, Gulf Coast
  • State or Province:FL
  • Country:USA
  • Interests:EE from Ga Tech, but I can't fix your TV, so don't ask ;-)
  • Year: 1998
  • Make: Pontiac
  • Model: Trans Am
  • Engine: 5.7L LS1
  • Transmission: 4L60-E Auto

Posted A week ago

This may not help a lot but I had the P0446 code with my 98 TA. It turned out to be a rotted hose at the tank EVAP vent valve. Now, I don't think that specific valve is used on other years, but maybe that helps a bit.


Edited by GaryDoug, A week ago.

gallery_14511_2130_2884.jpg
1998 Trans Am - LS1/A4 - all stock - one owner - driven daily - Scan9495 author


#11 nyan

nyan

    Firebird Newbie

  • New Member
  • Pip
  • 5 posts
  • Gender:Male
  • First Name:don
  • City:asheville
  • State or Province:NC
  • Country:USA
  • Year: 2000
  • Make: pontiac
  • Model: firebird
  • Engine: 3800
  • Transmission: 5 speed

Posted 6 days ago

 

In the factory service manual, the black "vent valve" appears to be referenced as the "Fill Limiter Vent Valve" (Volume 2 of 3, Part 2 of 2, Page 6-1263).  But I can't find any specs that define how it operates.  Interesting name though.  Appears easy to remove via a snap ring.

 

I would also be careful with pressuring the tank.  In the metal tanks, the pressure relief valve is set to open at 1 PSI

Googled fuel limit vent valve (FLVV). Most of the descriptions given describe a float in a tube that raises up with the fuel level. When the tank gets full, the float plugs the hole going to the vent system to prevent liquid fuel from entering the vent system and also to create pressure to shut off the fuel nozzle at the gas pump.

 

So, if that is accurate, then maybe a faulty FLVV in the tank is the root cause of the plugged cannister in that it was not sealing off the vent system when it should have? Going to try and remove that part and see if there might be a problem. Don't remember seeing a snap-ring...it kind of looked vulcanized or somehow sealed into the tank but either way it's coming out of there for inspection.

 

This may not help a lot but I had the P0446 code with my 98 TA. It turned out to be a rotted hose at the tank EVAP vent valve. Now, I don't think that specific valve is used on other years, but maybe that helps a bit.

Thanks GaryDoug! Nice find with the p0446 on your TA. The vent hoses on this one look like hard black plastic so cracks and damage are going to be a nightmare to find. I am so hoping that there is not a leak to chase down on this one.



#12 Injuneer

Injuneer

    Just Trying to Help

  • Administrator
  • 14126 posts
  • Gender:Male
  • First Name:Fred
  • City:Central NJ
  • State or Province:NJ
  • Country:USA
  • Interests:Licensed Professional Engineer (Mechanical)
  • Year: 1994
  • Make: Pontiac
  • Model: Firebird Formula
  • Engine: 381ci LT1 stroker
  • Transmission: TH400 + GV O/D

Posted 6 days ago

Float in the FLVV valve could be stuck open, allowing over-filling, or stuck closed preventing escape of fuel vapor.  I only mentioned the snap-ring because that's what is shown in the factory service manual.  I have no personal experience with the 98-02 fuel tanks.






0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users