Determining if gas cap is vented or not on 2011 Fleetwood Terra ts

[CP]

Decided to get a locking gas cap, but I do not know what kind I have (vented or non vented). We have a 2011 Fleetwood Terra with a ford chassis. Thought I would ask on the forum first if anyone knew for sure before I begin the hunt with Ford.  Also the current gas cap is secured to the coach (I assume the chord is held by a screw that can't be seen). Does anyone know if this is easy to get at to remove and if so how?

As usual your help is greatly appreciated.

Chuck

 

[mphy98]

All gas caps since the late 70's are non vented.  your fuel system is a sealed loop with a carbon canister.

 

[CP]

Thanks for your help. Have a great day.

Chuck

 

[PatrioticStabilist]

My gas caps were letting diesel leak out when driving.  I started to buy new caps but found they had gaskets in them.  I turned them over but they were to far gone.  I found the site and ordered new gaskets put them in the lids and that solved the problem.  The new caps aren't cheap.

 

[Wi1d Bill]

Check with Ford but I would bet that it is not vented.  The wrong one will make the "ENGINE WARNING" light come on. 

 

[CP]

Thanks to all for your input.

CP

 

[Bob Buchanan]

All gas caps since the late 70's are non vented.  your fuel system is a sealed loop with a carbon canister.

I read otherwise -- and so told by a mechanic in the Laughlin area. Yes, it is a closed system and that is why it must be vented via the cap. Because it is a closed system, as gas is used a vacuum begins - that if not released through the gas cap will suck gas back from the fuel line.

This happened to me. My rig was obviously starving for gas. When the gas cap was removed, a whooshing sound as air was sucked in happened. As I returned to NCal from AZ I would stop occasionally and unscrew then tighten the cap. It has not run other than normal since.

 

[mphy98]

I read otherwise -- and so told by a mechanic in the Laughlin area. Yes, it is a closed system and that is why it must be vented via the cap. Because it is a closed system, as gas is used a vacuum begins - that if not released through the gas cap will suck gas back from the fuel line.

This happened to me. My rig was obviously starving for gas. When the gas cap was removed, a whooshing sound as air was sucked in happened. As I returned to NCal from AZ I would stop occasionally and unscrew then tighten the cap. It has not run other than normal since.

Then you have a problem whti another part of you system.  If you were to have an emission test done they would check your gas cap for leaks under a vacume.  Now I know that motor homes do not have to go through this but as a dealership we test caps all the time.  A modern day system is totally sealed except for the carbon canister.

 

[ironrat]

Most get confused with this vented non vented cap issue. Most all use a vented cap, but it is vented in only one direction which is "in" to allow displacement of the fuel in the tank but sealed out to keep fumes out of the air. There are vented caps to go both ways but they are for old vehicles late 60's and older. Non vented was used on some 70's in very limited use. Your Ford should have a vented "in" cap on it.

 

[Bob Buchanan]

A modern day system is totally sealed except for the carbon canister.

Not sure what you mean by "modern day". Mine is a 96 Ford.

Others seem to disagree with you -- and I am only the nonMechanic trying to get the proper answer. From my experience so far, it appears my cap is supposed to be vented to release the vacuum and is not working properly. If I drive it with the cap tightly closed the engine will stall out. If I unscrew the cap and release the pressure - it runs properly.

Now I know that motor homes do not have to go through this but as a dealership we test caps all the time.

California requires a smog check on MH's every two years that includes a gas cap test in order to pass. Mine was tested and passed a bit over a year ago.

 

[carson]

This little link may help out a bit in understanding how it works.

here >>>> http://www.ehow.com/how-does_5057554_vented-gas-caps-work.html

 

[Gary RV_Wizard]

As ironrat says, some caps are vented in the sense that it allows air in but prevents fumes from going out. In other words, the vent has a check valve. The article Carson cites explains the details.  In a non-vented (closed) system the air enters via a valve in the vapor collection cartridge and there is no vent in the cap itself, in either direction.

I would not assume that the F53 chassis tank uses the same cap as a car or light truck - emissions standards are different for a medium duty vehicle, as is the fuel tank and fuel delivery system. So when you ask about the cap type, make sure you specify that it is the F53 motorhome chassis.  You can call Ford Motorhome Customer Service at 1-800-444-3311, available 24/7. They ought to be able to give a definitive answer for your particular chassis model. Have the VIN handy.

 

[CP]

Thanks Gary and to everyone.

I will give Ford a call and see what I get from them and let everyone know what they say.

Chuck