Cap for Schrader valve on fuel rail.

[uscgmac]

How important is that plastic cap on the pressure release valve or Schrader valve on the fuel rail for my 02 expedition. I was changing out the fuel filter and took the cap off to release the pressure in the fuel system and that little cap went flying into the unknown. Doubt I will find it. Can I just use a valve stem cap from a wheel or do I need that specific cap or do I even need a cap at all. Does it serve any purpose other then keeping dirt out of the valve. Thanks.

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[Trainmaster]

I think it just keeps the dirt out. I've had them fly away too, and it never presented a problem. Take a plastic one off the bicycle.

 

[TobyU]

Probably 30% of cars out there are missing it. Doesn't matter.

 

[uscgmac]

That's what I figured, thanks.

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[Yupster Dog]

I don't know about the rest of you but, in my opinion anything that keeps potential debris out of my injectors is a good thing. Would you run without your air filter in? no you would not because it would let actual debris in. I know this is apples and oranges to others but, actual debris and potential debris same thing to me. Do you think that Ford put that cap there for a reason or just to look pretty?

 

[TobyU]

I don't know about the rest of you but, in my opinion anything that keeps potential debris out of my injectors is a good thing. Would you run without your air filter in? no you would not because it would let actual debris in. I know this is apples and oranges to others but, actual debris and potential debris same thing to me. Do you think that Ford put that cap there for a reason or just to look pretty?

It doesn't do that.
Nothing goes in unless you screw something onto the port and have more pressure coming from your source than what is in the fuel rail , which is always 25+ PSI.
Any dust or debris that could settle however unlikely will just sit there until it falls or blows out or until a gauge is screwed on to the port which will blow it out with a little fuel with it.

It's not to look pretty. It's more like an industry decision (maybe even govt) to CYA and make it , or at least look safer.
Sure, there is a slight chance that if the valve leaked(never seen one) that the cap would keep fuel from being in hot engine area so a fire thing.
HOWEVER, lets be realistic, there is a lot greater chance of the flexible plastic/rubber fuel line cracking or leaking or the quick connect where the two lines hook to the fuel rail popping off.

So in reality, the cap being there or not is a moot issue.

 

[Yupster Dog]

Nothing goes in unless you screw something onto the port.

It's not to look pretty.

Sure, there is a slight chance that if the valve leaked so a fire thing.
[/QUOTE]

Toby,
Thank you for agreeing with me while telling me I'm wrong. You can run without cap all you want but in some states with annual vehicle inspections such as the commonwealth of Virginia not having that cap would fail your vehicle.
19VAC30-70-320. Fuel system. Inspect for and reject if: 1. Any part of the fuel system is not securely fastened.

So go without screwing something in your port and go with a slight chance of fire or buy a 50 cent cap.
I think the answer is clear here.
I'm going to eat a apple do you want a orange?

 

[Trainmaster]

There's a reason to keep any Schrader valve covered and anyone with a brain can figure it out. The cap protects the valve. It doesn't keep fuel in or keep dirt out of the fuel. It keeps crap from getting into the valve, causing it to fail to seat the next time you use it. It also fights corrosion of the valve.

 

[uscgmac]

My plan is to replace the cap. Obviously it will help protect the valve in the long run but short term I'm sure now that it isn't an issue to go without it for a little while. I just wanted to make sure it wasn't some type of a special cap that had another purpose other than just to cover and protect the valve. If I wanted the exact cap I would have to purchase a new valve also being it's sold as a set and can't find just the cap. It's a little different then a car tire valve cap in look as but size may be the same in diameter. I'm sure I can just throw another cap on it from a bike or car tire. My other dilemma now is waiting on my pcv elbow for my pcv hose to be delivered. Threw a lean code and have to replace some of the pcv elbows due to a vacuum leak. When my truck was inspected they never even popped the hood so nobody is looking to see if that little cap is there or not, lol.

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[TobyU]

Nothing goes in unless you screw something onto the port.

It's not to look pretty.

Sure, there is a slight chance that if the valve leaked so a fire thing.

Toby,
Thank you for agreeing with me while telling me I'm wrong. You can run without cap all you want but in some states with annual vehicle inspections such as the commonwealth of Virginia not having that cap would fail your vehicle.
19VAC30-70-320. Fuel system. Inspect for and reject if: 1. Any part of the fuel system is not securely fastened.

So go without screwing something in your port and go with a slight chance of fire or buy a 50 cent cap.
I think the answer is clear here.
I'm going to eat a apple do you want a orange?[/QUOTE]

You can get bent out of shape for me disagreeing with you...or "saying you were wrong" all you want. No harm there.
Just explaining that you comment about keeping potential debris out of injectors is not what it does.
It doesn't have anything to do with injectors or what gets to them.

I doubt they look for the cap in annual inspections because that is not a "fastened" item but VA is pretty picky and has garages do the inspections which is conflict of interest in itself so they might. Or at least some shops might pay attention. Now a fuel rail with bolts missing..that is not properly fastened and could lift up and injector could spray.

You would be hard pressed to find a typical mechanic (even at a dealer) who would bother to point out the port cap was missing or worry one second about it.
That's just how it plays out in day to day shops and repair people, professional or DIY.

For the other poster's comment about why it's there. Sure, but most cars will go their entire life an NEVER have anything screwed onto the port or the cap even taken off. Nothing there going to damage the valve.
Even tires run around all the time with no cap and does that cause a problem?? NOPE

Just lets the threads oxidize more.

Next you'll tell me it's important to have the plastic valve stem caps on you tires too.

Let's just say it makes some people feel better...much better apparently, but in daily life...if make little difference.

Do they check those at inspections too? They might. Some states are out of control ridiculous.
Just because a certain state or dealer or manufacturer says or recommends something doesn't really make it true.

I'm just saying for certain that you will have a fuel leak form a line connection before you will have an issue with the port valve form not having a cap on it.