bizarre gas leak please help
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From: omha
bizarre gas leak please help
i have a 1978 F250 with dual tanks, i have only used the main tank as i have never been sure that the saddle tank works, that said i have developed a gas leak from the top of the saddle tank? not sure how this works i have ensured that the saddle tank is empty in the past. why would it be leaking from the aux tank if i am not using it. couple other things it only leaks on occasion(mostly when it's hot) also the main tank is building up a lot of pressure this seems to increase the gas leak from the aux tank.any help? i have replaced the gas cap.
thanks
thanks
Last edited by Torque1st; Sep 6, 2006 at 03:47 PM.
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Please do not use strange small fonts, it is hard to read. Use the standard font in the standard post editor here.
The fuel may be leaking from the vent lines. Check your carbon canister and also your fuel selector valve for proper operation.
The fuel may be leaking from the vent lines. Check your carbon canister and also your fuel selector valve for proper operation.
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I suspect heat and expansion in the tanks.
If the truck is parked "driver's side toward the sun", that will cause a leak at the cap.
Are you filling them "Right to the nuts" every time ?
Don't do that.
My fuel tanks hold 76 Liters from empty. 76 divided by 4 = 19 US Gallons.
Try not putting more than 17 Gallon in from empty.
Sometimes the "straps to tanks" rust out causing a hole.
You need to deterine exactly where the leak is.
Also, there are "Vented caps" and "Non-vented caps" depending on the application.
If it's a non-vented cap then you have a vented fuel tank and probably Catalytic convertor.
Please post all the pertinent info about your truck as far as fuel & emissions related.
Pictures of the fuel tank would be good as well.
If the truck is parked "driver's side toward the sun", that will cause a leak at the cap.
Are you filling them "Right to the nuts" every time ?
Don't do that.
My fuel tanks hold 76 Liters from empty. 76 divided by 4 = 19 US Gallons.
Try not putting more than 17 Gallon in from empty.
Sometimes the "straps to tanks" rust out causing a hole.
You need to deterine exactly where the leak is.
Also, there are "Vented caps" and "Non-vented caps" depending on the application.
If it's a non-vented cap then you have a vented fuel tank and probably Catalytic convertor.
Please post all the pertinent info about your truck as far as fuel & emissions related.
Pictures of the fuel tank would be good as well.
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From: omha
not sure on the font issue, it doesn't look any different to me i didn't change the font
the gas will leak even if there is less than 1/4 of a tank. with gas at $3 a gallon and a gas leak i have not filled up for a long time. i replaced the gas cap with a vented cap. i am aware of the leak when you over fill but this is not the case. the weird part is that it leaks from the top of the front tank when there should be no gas in the front tank. i know where it's leaking from it is not the filler or vent it is from a piece that is sticking up about 6 inches from where the filler and vent is. not sure what that piece is, i can't quite see it. how can it leak from the front if i never put gas in the front tank? and what is that thing on top of the tank 6 inches from the filler and vent? forgive my lack of knowledge.
the gas will leak even if there is less than 1/4 of a tank. with gas at $3 a gallon and a gas leak i have not filled up for a long time. i replaced the gas cap with a vented cap. i am aware of the leak when you over fill but this is not the case. the weird part is that it leaks from the top of the front tank when there should be no gas in the front tank. i know where it's leaking from it is not the filler or vent it is from a piece that is sticking up about 6 inches from where the filler and vent is. not sure what that piece is, i can't quite see it. how can it leak from the front if i never put gas in the front tank? and what is that thing on top of the tank 6 inches from the filler and vent? forgive my lack of knowledge.
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It is part of the Unburnt fuel system.
It comes from the cannister located under the right front fender.
I'll see if I can find an illustration.
It comes from the cannister located under the right front fender.
I'll see if I can find an illustration.
Last edited by Mil1ion; Sep 7, 2006 at 01:20 PM.
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From: omha
when there is pressure in the rear tank it sprays out. then if i take the cap off and rellease the pressure it will slow.
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Are you sure you have the correct gas caps per your application ?
There many different kinds available.
You say you never put fuel in the aux tank,
Have you checked to see if there is any fuel in the aux at all ?
As per the other thread..aside from the fuel return line ,the only commonality between the 2 tanks is the fuel selector valve mounted between the 2 tanks.
There many different kinds available.
You say you never put fuel in the aux tank,
Have you checked to see if there is any fuel in the aux at all ?
As per the other thread..aside from the fuel return line ,the only commonality between the 2 tanks is the fuel selector valve mounted between the 2 tanks.
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From: omha
per the parts man, your choices in caps are non-vented, vented, and vented w/lock. i replaced it with a dupe of the original. it vents in but not out the plunger seems to go only one way.
the tank has been empty when checked. i knock on it sounds empty, ran the think completely out of gas, never filled up the aux tank. when the truck leaks the gauge on the main tank goes down. the gas that leaks is gas that originanated from the main that i am sure of.
what can i do about the pressure?
the tank has been empty when checked. i knock on it sounds empty, ran the think completely out of gas, never filled up the aux tank. when the truck leaks the gauge on the main tank goes down. the gas that leaks is gas that originanated from the main that i am sure of.
what can i do about the pressure?
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