1972 Fury III Fuel tank pressurizes when I drive

[MBar]

Had just got the car running and only put 2 or 3 gallons while I worked on things...she ran out of gas. No surprise but when I went to add more from my gas can, the tank "popped" when I released the cap. Added a couple gallons and drove it to the gas station and it popped again when I removed the cap. When I first got the car, I replaced all the rubber fuel lines, filter and blew out the steel lines, dropped the tank and dumped the bad fuel (no rust) but didn't pull the sending unit. The car runs fine otherwise.
I am suspecting something with the canister maybe a filter? I'm gonna do some research but does anyone have a quick answer?

 

[HWYCRZR]

Is it pressurizing or creating a vacuum? I don’t know exactly how the canisters works, but they were put in to capture fumes from the gas. If a vent line is plugged going in or out of the canister it can create a vacuum and have the symptoms of running out of gas. As soon as you vent the cap the vacuum goes away and it will run for a while longer. If you are familiar with an old out board boat fuel can you have probably experienced the same thing when you forget to open the vent cap.
Your field service manual should have some troubleshooting tips for the vent canister.

 

[Davea Lux]

Had just got the car running and only put 2 or 3 gallons while I worked on things...she ran out of gas. No surprise but when I went to add more from my gas can, the tank "popped" when I released the cap. Added a couple gallons and drove it to the gas station and it popped again when I removed the cap. When I first got the car, I replaced all the rubber fuel lines, filter and blew out the steel lines, dropped the tank and dumped the bad fuel (no rust) but didn't pull the sending unit. The car runs fine otherwise.
I am suspecting something with the canister maybe a filter? I'm gonna do some research but does anyone have a quick answer?

Could be a couple of things, if the tank is building pressure, that usually means the one or both tailpipes is too close to the side of the tank causing rapid evaporation of the fuel. This can also happen if somebody has routed the tailpipes under the fuel tank.

A clogged vent pipe will usually result in creating a vacuum in the tank as the fuel pump removes fuel not pressure.

Dave

 

[MBar]

Is it pressurizing or creating a vacuum? I don’t know exactly how the canisters works, but they were put in to capture fumes from the gas. If a vent line is plugged going in or out of the canister it can create a vacuum and have the symptoms of running out of gas. As soon as you vent the cap the vacuum goes away and it will run for a while longer. If you are familiar with an old out board boat fuel can you have probably experienced the same thing when you forget to open the vent cap.
Your field service manual should have some troubleshooting tips for the vent canister.

actually, Vacuum.... thanks for clarifying me....

 

[CBODY67]

The tank vents into the carbon canister. The gas cap should be "pressure release" with different tangs than prior model years. There are some pressure-bias valves on the canister, too.

If you suspect the tank is being pressurized, or having a vacuum pulled on it, then you can probably remove the rubber line from the tank at the canister and see if the problem persists.

It's not unusual to hear a hissing sound when taking the fuel cap off, from the tank pressurizing a bit from normal fuel slosh, especially in warmer weather. But if it's a vacuum, that's not good!

Check to see that the gas cap is the correct one for the car, as a first step.

CBODY67

 

[Davea Lux]

If you have vacuum, remove the fuel cap and unhook the vent line from the canister in the engine compartment. Use a tire pump or some other low pressure air source and see if the line holds pressure. If the line holds pressure, the line is plugged someplace. If the line blows clear, most likely the canister or the canister check valve (if it has one) is bad. Check the hose routing decal in the engine compartment to be sure the vent system hoses are properly attached and hooked to the right place.

Dave

 

[MBar]

The tank vents into the carbon canister. The gas cap should be "pressure release" with different tangs than prior model years. There are some pressure-bias valves on the canister, too.

If you suspect the tank is being pressurized, or having a vacuum pulled on it, then you can probably remove the rubber line from the tank at the canister and see if the problem persists.

It's not unusual to hear a hissing sound when taking the fuel cap off, from the tank pressurizing a bit from normal fuel slosh, especially in warmer weather. But if it's a vacuum, that's not good!

Check to see that the gas cap is the correct one for the car, as a first step.

CBODY67

saw your reply just as I asked the cap question --thank you

 

[1970FuryConv]

Hi Mbar

I agree with all suggestions that you may have a clogged vent hose system that is creating vacuum as fuel leaves the tank and air is not let in to fill the vacated space inside the tank.

Unless you have a station wagon, you don't have the limiting valve mentioned in the evap emissions section below.

The wrong gas cap may be part of the problem as well, since the cap is supposed to relieve excess vacuum, see 1972 factory shop manual, 25-16 below

BTW, I do not have my distributor vacuum advance or PCV tee'd to the canister purge valve. I do get a slight hiss sometimes when I start to turn the gas cap. 72 Furies rule! Mine is pictured.

Post a pic of your 72 if you have a moment. Would love to see it.

 

[PurpleBeeper]

Had just got the car running and only put 2 or 3 gallons while I worked on things...she ran out of gas. No surprise but when I went to add more from my gas can, the tank "popped" when I released the cap. Added a couple gallons and drove it to the gas station and it popped again when I removed the cap. When I first got the car, I replaced all the rubber fuel lines, filter and blew out the steel lines, dropped the tank and dumped the bad fuel (no rust) but didn't pull the sending unit. The car runs fine otherwise.
I am suspecting something with the canister maybe a filter? I'm gonna do some research but does anyone have a quick answer?

See all of the GREAT advice above....yes, it seems like a charcoal canister issue. You might consider temporarily adding a vented gas cap until you get it worked out.

 

[MBar]

Hi Mbar

I agree with all suggestions that you may have a clogged vent hose system that is creating vacuum as fuel leaves the tank and air is not let in to fill the vacated space inside the tank.

Unless you have a station wagon, you don't have the limiting valve mentioned in the evap emissions section below.

The wrong gas cap may be part of the problem as well, since the cap is supposed to relieve excess vacuum, see 1972 factory shop manual, 25-16 below
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BTW, I do not have my distributor vacuum advance or PCV tee'd to the canister purge valve. I do get a slight hiss sometimes when I start to turn the gas cap. 72 Furies rule! Mine is pictured.
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Post a pic of your 72 if you have a moment. Would love to see it.

Thanks man .. ok here it is: we call it the green monster (during the holidays its the GrinchMobile)... I really thought the front was kinda ugly/weird but it has grown on me... I tried to get a shot of both my Mopars. The Fury is a bit banged up on the right side. The left is ok..zero rust anywhere..

 

[1970FuryConv]

Like the green monster.

72 Fury grill is a personal favorite. Love the grill inserts and loop bumper.

 

[MBar]

Like the green monster.

72 Fury grill is a personal favorite. Love the grill inserts and loop bumper.

Thanks man!... she's got me frustrated....since I brought her back to life she is showing me the leaks....just did tranny service and torqued bolts correctly and it's leaking pretty good - not from the pan but somewhere in rear of trans...also I think the rear main oil seal of the motor but not a dripper. And, the PS box is leaking from the top....and ONE freeze plug (next to the starter) is looking iffy....getting frustrated and the idea of selling is starting to creep in. Pity because the motor is stong and smooth and the trans shifts nicely but the suspension rubbers are all rotted...
I have 3 other projects sitting (69 Bronco, 69 Vette Conv and 73 Opel GT) plus my 68 Newport which is in great shape. I had lost my wrenching mojo and the Vette, which is sitting among all new parts was guilting me... This car woke me up with all the stuff I hadn't anticipated and I am wondering how much to give this green monster before I turn to more valuable cars....and my budget is not strong either... Wonder what my more-door is worth now...and if anyone would want it...sigh.. here are some pics of my 68 Newport

 

[1970FuryConv]

1972 Fury III 360 101498 miles
Hi Mbar

I understand you on the level of work. My car's thread, see above, is 18 pages and counting.

I understand you on the leaks. Since buying my Fury, I dealt with brake wheel cylinder leaks, locked brake calipers, trans pan and dipstick tube leaks, oil pan and valve cover leaks, radiator leaks, etc. I have put a year of work into my car after buying it in January 2018. Probably the worst was dropping the transmission so I could fix freeze plug leaks at the back of the block.

However, I have managed to turn my 1972 Fury into an awesome driver. And I really like my car.

I can’t set your priorities for you. Generally, I would say if you don’t like the car, sell it and work on something you do like. We often get caught between "not quitting" versus "cutting your losses and moving on". With my car, I had always wanted a 1972 Fury. I thought about buying one for the last 20 years and finally got off my *** and bought this car. I really like mine and think of it as my friend. I find myself complimenting the car while I am alone driving it and there are no other people to hear. If you don't like your car or think of it as your friend, I'd suggest that it's time to cut your losses and sell.

 

[MBar]

1972 Fury III 360 101498 miles
Hi Mbar

I understand you on the level of work. My car's thread, see above, is 18 pages and counting.

I understand you on the leaks. Since buying my Fury, I dealt with brake wheel cylinder leaks, locked brake calipers, trans pan and dipstick tube leaks, oil pan and valve cover leaks, radiator leaks, etc. I have put a year of work into my car after buying it in January 2018. Probably the worst was dropping the transmission so I could fix freeze plug leaks at the back of the block.

However, I have managed to turn my 1972 Fury into an awesome driver. And I really like my car.

I can’t set your priorities for you. Generally, I would say if you don’t like the car, sell it and work on something you do like. We often get caught between "not quitting" versus "cutting your losses and moving on". With my car, I had always wanted a 1972 Fury. I thought about buying one for the last 20 years and finally got off my *** and bought this car. I really like mine and think of it as my friend. I find myself complimenting the car while I am alone driving it and there are no other people to hear. If you don't like your car or think of it as your friend, I'd suggest that it's time to cut your losses and sell.

WOW..I have been reading your thread.. Kinda wish I had one thread on mine instead of a bunch of them..I am learning this forum stuff as I go.
Though I am griping a little (venting perhaps?) I think it might be too late.... I think I'm in the "love" stage now... your encouragement is invaluable...and yes, I find myself standing in the driveway staring and admiring (and complimenting the darn thing even when it wasn't running)...I think if I ever sell it, the buyer would have to be someone that feels the same way you do. I guess I realize that I am in no hurry. I am not hurting for the dough I would get from selling and she can live on the street (registered and insured) while I sort it out.
At first I thought it was an ugly car so it is very nice to find someone that is partial to the 72. Thank you

 

[PurpleBeeper]

Thanks man!... she's got me frustrated....since I brought her back to life she is showing me the leaks....just did tranny service and torqued bolts correctly and it's leaking pretty good - not from the pan but somewhere in rear of trans...also I think the rear main oil seal of the motor but not a dripper. And, the PS box is leaking from the top....and ONE freeze plug (next to the starter) is looking iffy....getting frustrated and the idea of selling is starting to creep in. Pity because the motor is stong and smooth and the trans shifts nicely but the suspension rubbers are all rotted...
I have 3 other projects sitting (69 Bronco, 69 Vette Conv and 73 Opel GT) plus my 68 Newport which is in great shape. I had lost my wrenching mojo and the Vette, which is sitting among all new parts was guilting me... This car woke me up with all the stuff I hadn't anticipated and I am wondering how much to give this green monster before I turn to more valuable cars....and my budget is not strong either... Wonder what my more-door is worth now...and if anyone would want it...sigh.. here are some pics of my 68 Newport

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Don't give up! The trans leak at the back I most likely the rear main seal which can be replaced by just removing the driveshaft. The rear main seal of the engine can be replaced by dropping the center link & dropping the oil pan. You could do the whole thing in a weekend if you worked fast.

 

[MBar]

Don't give up! The trans leak at the back I most likely the rear main seal which can be replaced by just removing the driveshaft. The rear main seal of the engine can be replaced by dropping the center link & dropping the oil pan. You could do the whole thing in a weekend if you worked fast.

Thanks for the advice man! We are getting rain for a couple days and here that is a big (debilitating) deal..LOL
The trans seal sounds easy enough and would give me a chance to replace the Ujoints just-in-case... The PS leak is likely the O rings to the valve body on the box (gotta find those but so far it looks like 50 bucks..ouch) so that will be ok. When I did my timing chain I explored dropping the engine pan but lots of people said that is a PITA so I am afraid. Luckily that doesn't seem to be a severe dripper - just see a lot of oil on the bottom but I think I could live with that.
Have you dropped the pan on yours? did you have to release the motor mounts and raise the motor too? Was the gasket a pain to remove to have a clean surface?
I have the car parked across the street and the rain sure made it look shiny and nice as I was driving off to work this morning.

 

[1970FuryConv]

Mine has a 360. I had to detach the motor mounts & raise the engine to do my oil pan. Lots of pieces of valve seal in the pickup.

 

[ImpJay]

Thanks man!... she's got me frustrated....since I brought her back to life she is showing me the leaks....just did tranny service and torqued bolts correctly and it's leaking pretty good - not from the pan but somewhere in rear of trans...also I think the rear main oil seal of the motor but not a dripper. And, the PS box is leaking from the top....and ONE freeze plug (next to the starter) is looking iffy....getting frustrated and the idea of selling is starting to creep in. Pity because the motor is stong and smooth and the trans shifts nicely but the suspension rubbers are all rotted...
I have 3 other projects sitting (69 Bronco, 69 Vette Conv and 73 Opel GT) plus my 68 Newport which is in great shape. I had lost my wrenching mojo and the Vette, which is sitting among all new parts was guilting me... This car woke me up with all the stuff I hadn't anticipated and I am wondering how much to give this green monster before I turn to more valuable cars....and my budget is not strong either... Wonder what my more-door is worth now...and if anyone would want it...sigh.. here are some pics of my 68 Newport

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I love the color on your Newport! Is it the original Sky Blue Irid? Not against the Fury, Fusies are always nice in my mind.

 

[MBar]

I love the color on your Newport! Is it the original Sky Blue Irid? Not against the Fury, Fusies are always nice in my mind.

I love the color on your Newport! Is it the original Sky Blue Irid? Not against the Fury, Fusies are always nice in my mind.

Actually it's a cheap Maaco 399 paint job... I was under pressure to pick a color and I didn't know to check the tag so I looked at samples and eyeballed one... Sky Blue sounds familiar... but now I think the original color was a Teal... I'll have to look up my tag soon and see... The car has sat in the sun for about 4 years since paint and the cheap job has turned kind of a flat hue...but I like it so it worked out... Someday I would like to go back to original...

 

[MBar]

I love the color on your Newport! Is it the original Sky Blue Irid? Not against the Fury, Fusies are always nice in my mind.

Looked at the fender tag on the Newport today... DD1 - online it says Sky Blue. On the fender tag decoder it says Monotone Light Blue Metallic.. Pretty sure I told the painter that but when I compare door jams it seems like the original color had more of a teale tint...