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Fuel leak at cap on fuel rail

Tiny
MRS.ATKINSON
  • MEMBER
  • 2001 DODGE CARAVAN
  • 3.8L
  • V6
  • 2WD
  • AUTOMATIC
  • 145,000 MILES
I have been chasing fuel smells around on this van for a couple of months.
My mechanic replaced the charcoal canisters nothing showed up in a smoke test. That fixed the problem for a little while and then the smell came back and that's when I discovered a little cap on the end of my fuel rail that was leaking.
I replaced the o-ring (took two tries to get the right o-ring) And that seemed to fix the problem, for about two weeks.
Now it's leaking again.
I started it up and watched it leak for a minute or two, turned the ignition off, and on a whim open the gas cap. I got a puff of pressure, then I restarted the car and it was no longer leaking out of there.
I checked the fuel pressure relay and fuse both are fine.
So, any ideas as to what is causing this excess pressure? I believe the fuel pressure regulator on this model is located on the fuel pump in the gas tank, which is not something I can work on here in the street in front of my house. I hate to send it to a shop if that is not the solution.
Any insight would be appreciated.
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Thursday, August 29th, 2019 AT 5:11 PM

8 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Hi,

It could be excessive pressure but let's test it to find out for sure.

Here is a guide that will walk you through that:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Can you take a picture of the port that is leaking just so I can get on the same page? I think I know what you are referring to but I just want to make sure.

Let me know what the fuel pressure is and send that picture over and we can go from there but I think you may be on the right path with the regulator which is on the pump in the tank. Thanks
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Thursday, August 29th, 2019 AT 7:27 PM
Tiny
MRS.ATKINSON
  • MEMBER
  • 5 POSTS
This is the pressure key on/ engine off https://youtu.be/D9h2qeXUl6M

Now with engine running and leak beginning https://youtu.be/lL4dTyyC5yw

The engine runs fine, always starts, no hesitation, and enough power to pull the local hills.
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Sunday, September 1st, 2019 AT 12:01 PM
Tiny
MRS.ATKINSON
  • MEMBER
  • 5 POSTS
This is a stock photo of my fuel rail ( photo is reversed, cap is on drivers side) And someone else's photo of the cap that is leaking ( mine is exactly the same).

https://photos.app.goo.gl/oHa9AKp7TgreEJdGA

.

I removed my cap and replaced the o-ring. O'rileys sold me the wrong one the first time so I tracked down an original mopar one and put that in.
I think It may be a coincidence that the leak stopped for a little while. The original o-ring looked okay, and the replacement is an exact match.
I'm sure I have it seated properly because it stopped leaking that time I opened the gas cap.
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Sunday, September 1st, 2019 AT 12:09 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Okay. Pressure is okay at 60. Spec is 58 +/- 5 so you are right on it.

Also, the link of the part that you are talking about did not work. Is there a way you can send it again? I am interested in seeing what the part looks like because when I find a drawing of the fuel rail it does not have the part you are showing on it. If I see it I am hoping to identify it and then we can go from there.

Since you don't have excess pressure clearly we are just dealing with a sealing issue so hopefully I can identify it and we can go from there.

If the link doesn't work, just take a screen shot of the part you found and then save it to your computer and upload it as an attachment with the link below your text box.
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Monday, September 2nd, 2019 AT 6:28 PM
Tiny
KASEKENNY
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Does the piece you are talking about have metal tangs or clips that hold it down into the rail? Then the o-ring is at the bottom?

If so, this is more than likely just a dampener meant to smooth out fuel pulses. As you can see the fuel pressure jumps around (flutters) when running so this dampener is just there to smooth it out. However, this is not a serviceable part so once it is removed those tangs loose their tension and more than likely the only way you will fix it is to replace the rail which should come with this already installed.

Let me know what you think. Thanks
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Monday, September 2nd, 2019 AT 7:08 PM
Tiny
MRS.ATKINSON
  • MEMBER
  • 5 POSTS
Yes, It is the cap you are describing. It is marked "do not remove" (which is impossible to read until after you remove it!). It does not seem to "seat" into anything, and I agree that it is a damper. I compared it to a water hammer arrestor when I was trying to describe it.
I was extremely careful in removing and replacing it and the tangs are completely fitted under the flared end of the little tube thing it fits on.
I don't understand what would prevent it from being serviceable, but that's beside the point.
Is this a part that would fail from old age? (The o-ring looked okay) If not, what would cause it to fail?
I really hate working on cars, so as long as I have to replace the fuel rail I want to get whatever the root cause is, too.
Also, what do you think about an amateur changing a fuel rail out? I'm pretty handy and I have a basic understanding of, how engines work.
I have a very modest income, so I need to do it myself if I can.
Any special considerations or specs in reassembly I should be aware of?
And thanks for your help.
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Monday, September 2nd, 2019 AT 11:54 PM
Tiny
MRS.ATKINSON
  • MEMBER
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This is what the cap looks like (not my photo). It sits in a tube near the end of the rail. It doesn't click in, just pushes in until the tabs go over the flare on the rim of the tube and lock it on.
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Tuesday, September 3rd, 2019 AT 6:23 AM
Tiny
KASEKENNY
  • MECHANIC
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Yes, okay. We are on the same page. That is in fact what we are saying is a damper. Unfortunately, what happens is when it is removed, those tangs do not hold enough tension on the assembly which causes it to lift just a bit when the pressure goes up to peak pressure of about 64-66 PSI.

Here is the procedure from the book on how to replace the rail. This includes removing the upper intake. It is not the easiest thing but can be done in a driveway.

Please let me know if you have questions and I will be happy to help. Thanks
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Tuesday, September 3rd, 2019 AT 8:12 PM

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