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Constant fuel pressure on passenger side fuel line

Tiny
RADCRO
  • MEMBER
  • 2013 CHRYSLER 300
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 75,000 MILES
Car listed above is a 300C with a fuel leak on passenger side fuel pump/filter assembly we think from the top of the plastic part itself. We changed the o-ring first but it still leaks. I have the new part but now I can't pull the passenger side fuel line off because of constant fuel pressure on that line even with the driver side pump unplugged. When I changed the o-ring I had almost 3/4 of a tank of gas but now I let the tank level drop to 1/4 full. What could cause constant pressure on the passenger side fuel line when the pump is unplugged?
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Thursday, January 2nd, 2020 AT 12:22 PM

22 Replies

Tiny
ASEMASTER6371
  • MECHANIC
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Good afternoon,

Is this the line that has the leaking fitting?

Roy
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Thursday, January 2nd, 2020 AT 12:43 PM
Tiny
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No, on a 2013 - 300C there is a pump assy under the back seat drivers side and the fuel line, filter and gas gauge sending unit on the passenger side. I can't delete the photo below with the other website on it.
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Thursday, January 2nd, 2020 AT 1:24 PM
Tiny
ASEMASTER6371
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Okay, that line provides the fuel pressure to the rail, as you know.

Why are you changing the fuel pump?

There is residual pressure after the car is turned off. It is designed to operate like that.

Remove the electrical connector and start the engine. It will bleed down the system to allow the removal of the line.

Roy
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Thursday, January 2nd, 2020 AT 1:34 PM
Tiny
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That is exactly what I did, pull the wires off of the driver side pump, start the car until it stalls, go to the passenger side to remove the gas line off the plastic part shown above (that goes to fuel rails) but there is still pressure in that line. It doesn't make sense.
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Thursday, January 2nd, 2020 AT 1:42 PM
Tiny
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I would expect to have some pressure but pressure doesn't reduce when I start to pull the line.
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Thursday, January 2nd, 2020 AT 1:44 PM
Tiny
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I didn't remove the relay I just unplugged the pump. Would it matter?
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Thursday, January 2nd, 2020 AT 1:47 PM
Tiny
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The reason I need to change the passenger side is that it leaks from the top of the plastic. I changed the gasket on the passenger side once already. That's why none of this makes any sense. I did this without issue 2 weeks ago.
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Thursday, January 2nd, 2020 AT 1:50 PM
Tiny
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Remove the relay and see if still has pressure.

Do you have a test fitting on the fuel rail in the front?

Roy
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Thursday, January 2nd, 2020 AT 1:57 PM
Tiny
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Earlier today I was able to release the drivers side fastener and disconnect all the fuel lines (3) that run to the passenger side assembly. When I went to the passengers side to disconnect the fuel line from the top of the part I want to replace, the pressure was too much to disconnect. So I stopped and reconnected everything back to the original config.
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Thursday, January 2nd, 2020 AT 2:02 PM
Tiny
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No, I haven't done anything near the actual fuel rail or anything under the hood.
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Thursday, January 2nd, 2020 AT 2:03 PM
Tiny
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You should check there.

Did you follow the procedure I posted for the bleed down?

Roy
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Thursday, January 2nd, 2020 AT 2:04 PM
Tiny
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Let me try the relay instead of just unplugging the pump and see if that helps the pressure.
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Thursday, January 2nd, 2020 AT 2:04 PM
Tiny
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So I pulled the fuel pump relay (#54) from under the hood, started the car and it keeps running, sluggish and sputtering but the engine never shut off. Stepping on the gas didn't rev the engine, just caused stuttering.
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Thursday, January 2nd, 2020 AT 2:37 PM
Tiny
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Either that is not the relay or you did not leave it run long enough to run out of fuel.

Roy
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Thursday, January 2nd, 2020 AT 2:43 PM
Tiny
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I think I may just get a gas can and gas line, pull the battery and make a quick swap of the fuel line to see how much gas will siphon out into the gas can. I'm speculating that it could be some type of pressure equalization that needs to occur on both sides of the tanks to stop the flow.
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Thursday, January 2nd, 2020 AT 2:51 PM
Tiny
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You are correct, but the residual pressure should drop to zero with the pump not working.

Roy
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Thursday, January 2nd, 2020 AT 2:54 PM
Tiny
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It ran for about 2.5 to 3 minutes before I shut it off. It is the same result as when I removed the 5 pin connector from the backseat driver's side fuel pump. I would think that the engine should die within 1 minute of starting. Yes?
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Thursday, January 2nd, 2020 AT 3:09 PM
Tiny
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Correct. Did you check for a valve on the fuel rail in the front?

Roy
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Thursday, January 2nd, 2020 AT 4:19 PM
Tiny
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The fuel rail Schrader valve? I haven't check to see if there is one, that would be a great place to relieve fuel line pressure.
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Friday, January 3rd, 2020 AT 10:39 AM
Tiny
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That is correct check on the fuel rail for the valve.

Roy.
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Friday, January 3rd, 2020 AT 11:23 AM

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