2008 E320 CDI/Bluetec in-tank fuel pressure loss.
Thread Starter
Junior Member
Joined: May 2014
Posts: 34
Likes: 2
From: Ontario, Canada
2008 E320 Bluetec | 2011 Dodge Durango Citadel | 1965 Mustang Coupe 289 | 2015 Triumph Speedmaster
2008 E320 CDI/Bluetec in-tank fuel pressure loss.
Greetings!
Does anyone know if there is a fuel pressure regulator and/or a check valve in the in tank sending unit (left side of tank) or with the in tank fuel pump assembly (right side of tank)? I tested my in tank fuel pump and it pushes 60psi but once the pump stops priming I loose pressure completely, down to 0 psi. I'm guessing it's the in tank pressure regulator that isn't holding pressure or is leaking or maybe the check valve (if there is one) that is worn out/leaking.
Thanks for the help in advance!
Does anyone know if there is a fuel pressure regulator and/or a check valve in the in tank sending unit (left side of tank) or with the in tank fuel pump assembly (right side of tank)? I tested my in tank fuel pump and it pushes 60psi but once the pump stops priming I loose pressure completely, down to 0 psi. I'm guessing it's the in tank pressure regulator that isn't holding pressure or is leaking or maybe the check valve (if there is one) that is worn out/leaking.
Thanks for the help in advance!
Senior Member
Joined: Jan 2011
Posts: 422
Likes: 52
From: McDade, Texas
W211 e320 CDI
Could also be a hose internal to tank leaking....thinking back to when I replaced mine, it seems like there was a hose between the pump and outlet spigot but not 100% sure on that. Also make sure fuel hoses are tight at filter under hood....had that issue once too.
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Joined: Jan 2009
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From: V E G A S
1922 Ford Model T / no OBD
You must be talking about check valve?
Whatever it is, the only thing you can buy is whole pump assembly (some models need whole new tank), but if you like DIY, take it apart and clean.
Be careful with installation as saddle tank uses maze of tubing with Venturi effect to transfer fuel from 1 side to the other and small misalignment makes fuel sitting on passenger side, when pump on driver side runs dry.
Whatever it is, the only thing you can buy is whole pump assembly (some models need whole new tank), but if you like DIY, take it apart and clean.
Be careful with installation as saddle tank uses maze of tubing with Venturi effect to transfer fuel from 1 side to the other and small misalignment makes fuel sitting on passenger side, when pump on driver side runs dry.
Thread Starter
Junior Member
Joined: May 2014
Posts: 34
Likes: 2
From: Ontario, Canada
2008 E320 Bluetec | 2011 Dodge Durango Citadel | 1965 Mustang Coupe 289 | 2015 Triumph Speedmaster
So from extensive research I found out that there are check (ball) valves within the in-tank fuel pump, internal in the motor. I also found out my fuel pressure loss isn't as a result of these valves in the in-tank pump... the fuel isn't returning back to the tank from the supply line which proves these check valves are seating properly and since fuel supply pressure is around 60psi my in-tank pump is operating properly. I pinched off the supply line to the fuel filter after it primed and my make-shift pressure gauge still dropped completely to 0 psi. I did another bleed off test with the engine off, letting the fuel system prime and pinched the return line after the fuel rails and the pressure stopped dropping so this indicates the pressure loss is likely happening at the pressure control valve (regulator) on the fuel rail which should normally be closed at startup.
My next step is to see if replacing just the regulator works instead of the whole rail like the dealership wants everyone to do. The difference is $700+-. (Dealership wants $938 CAD for new rail with regulator). The dealership says changing the regulator (instead of whole assembly) doesn't work or fails so they will only change the complete rail with a new regulator. I'm going to go against the grain to see if this is true and report my findings. I thought I'd follow up for the benefit of others in this forum.
Cheers
My next step is to see if replacing just the regulator works instead of the whole rail like the dealership wants everyone to do. The difference is $700+-. (Dealership wants $938 CAD for new rail with regulator). The dealership says changing the regulator (instead of whole assembly) doesn't work or fails so they will only change the complete rail with a new regulator. I'm going to go against the grain to see if this is true and report my findings. I thought I'd follow up for the benefit of others in this forum.
Cheers
Last edited by BenzKraft; Aug 20, 2018 at 10:33 AM. Reason: Clarification
Thread Starter
Junior Member
Joined: May 2014
Posts: 34
Likes: 2
From: Ontario, Canada
2008 E320 Bluetec | 2011 Dodge Durango Citadel | 1965 Mustang Coupe 289 | 2015 Triumph Speedmaster
My next step is to see if replacing just the regulator works instead of the whole rail like the dealership wants everyone to do. The difference is $700+-. (Dealership wants $938 CAD for new rail with regulator). The dealership says changing the regulator (instead of whole assembly) doesn't work or fails so they will only change the complete rail with a new regulator. I'm going to go against the grain to see if this is true and report my findings. I thought I'd follow up for the benefit of others in this forum. Cheers
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2007 E320 Bluetec
Fuel line check valve
Greetings!
Does anyone know if there is a fuel pressure regulator and/or a check valve in the in tank sending unit (left side of tank) or with the in tank fuel pump assembly (right side of tank)? I tested my in tank fuel pump and it pushes 60psi but once the pump stops priming I loose pressure completely, down to 0 psi. I'm guessing it's the in tank pressure regulator that isn't holding pressure or is leaking or maybe the check valve (if there is one) that is worn out/leaking.
Thanks for the help in advance!
Does anyone know if there is a fuel pressure regulator and/or a check valve in the in tank sending unit (left side of tank) or with the in tank fuel pump assembly (right side of tank)? I tested my in tank fuel pump and it pushes 60psi but once the pump stops priming I loose pressure completely, down to 0 psi. I'm guessing it's the in tank pressure regulator that isn't holding pressure or is leaking or maybe the check valve (if there is one) that is worn out/leaking.
Thanks for the help in advance!
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