filler neck allen screw what is it for?

[1996crownvicman]

Question???? hey all I have a 1996 factory crown vic cng car, and i was noticing the smell of ng in the trunck after filling it up at my home filling station- i tracted it down to under a rubber cover around the filler neck inside the fender well of the rear tire byt the filler neck it has a allen screw- when turned one way it stops the blubbles when tested with soapy water solution- and when the screw is turned the other way too-many tuns it releases NG out tof the filler neck where pumped in to. so my delima is let the car run till really low on NG and release the last remaining NG and pull out screw all the way and wrap teflon tape and re-tighten and re-fill up tanks whats your opion??


Thanks

Ryan

[afvman]

Re: filler neck allen screw what is it for?

Hello Ryan,

First, be careful! Before you do any work on that valve, shut off all of the cylinder valves and run the engine until it quits to depressurize the system. If they have manual valves this is easy. But, I believe the Crown Vic's had electric solenoid cylinder valves and if so, disconnect the two wire connector to them and the valves will stay shut (Normally Closed) or should.

That allen screw (metric 5 mm) opens or closes a check valve behind the NGV2 fill recepticle. It's used, along with a special tool from Ford, to vent cylinders. There are 3 or 4 'O' rings, any of which could be leaking. One under the big hex nut surrounding that allen screw, one in front of the filter at the rear of that assembly and 3 on the NGV2 receptacle itself.

Try to pin down exactly where it's coming from first, then proceed carefully with the depresurrization above to fix it.

Stay safe,

afvman/Bill

[1996crownvicman]

Re: filler neck allen screw what is it for?

thank you, I will let it pressure down 1st and let the engine run it self out of gas 1st and then i will take it apart are the 0-rings anything special or are they ones i can buy over the counter at any auo parts shop?

Thanks

[larrycng]

Re: filler neck allen screw what is it for?

Here is what you're dealing with (if you get the picture).

Make sure "O" are compatable with methane (ng). Use a SMALL amout of silicone grease or spray on the "O" rings.

I would use all new "O" rings (my preference)

Becareful how you put valve in a vice so you do not distort the housing causing binding. And of course make sure the parts are in the correct order.

Larrycng

[jasongainesville]

Re: filler neck allen screw what is it for?

I am having the same problem.. what was your fix? any suggestions?
-j