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2008 JDM Outback 3.0R, 5EAT
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Discussion Starter #1
I'm planning to run my first fuel pressure test for a small injector leak so started reading up. Lot's of docs and FSM's mention the FPR as part of the fuel pressure test procedure.

The weird thing is the FSM section for my engine (a 2007 JDM 3.0R) clearly excludes references to the FPR whereas the sections for other engines describe FPR diagnoses, removal and installation.

Checking under the hood bonnet there is a fuel damper valve on the fuel delivery line on the LHS forward of the firewall and one fuel damper on each of the fuel rails. The purge control components are underneath the air intake.

So got me thinking and thought to ask a beginner question,how does the system balance fuel delivery pressure and return without a FPR ?
 

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Your JDM2007 is probably the equivalent to our North American MY2008. My FSM for 2008 does not show a separate Fuel Pressure Regulator for the H6. Like my 2007 H4, the FPR is probably integrated into the fuel pump assembly, and the instructions for testing the fuel pressure do not mention the FPR.

When the FPR is in the engine compartment, there's usually three tubes that come from the fuel tank to the left side of the engine compartment and then on to the engine. One is the fuel delivery, another goes to the purge valve, and the third is the return line to the fuel tank for excess fuel bypassed by the FPR. When the FPR is in the fuel pump assembly, the third tube is absent.

Another way to verify the system is to look at the top of the fuel pump. If there's only two hose fittings, then the FPR is inside the pump housing; if there's three, than one of those is the return line from the FPR at the engine.
 

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2008 JDM Outback 3.0R, 5EAT
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Discussion Starter #3
Another way to verify the system is to look at the top of the fuel pump. If there's only two hose fittings, then the FPR is inside the pump housing; if there's three, than one of those is the return line from the FPR at the engine.
Yes the two fittings - after recently working on this I wondered why there's two fittings ? Is it one to supply the engine and the other to dump additional fuel from the in-tank regulator to the other side of the tank ?
 

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Yes the two fittings - after recently working on this I wondered why there's two fittings ? Is it one to supply the engine and the other to dump additional fuel from the in-tank regulator to the other side of the tank ?
Close, but not the right direction. One fitting is the supply to the engine; the other is the transfer line from the part of the tank on the left (your passenger) side.

The tank bridges over the drive shaft, much like a pair of saddle bags. With the pump on the right side, it needs a way to draw fuel from the part of the tank on the left side. On the pump assembly, part of the fuel being pumped by the electric motor is routed to a venturi tube. The fuel passing through the tube causes a vacuum on part of the tube. That part is connected by the second fitting and hose to a pickup in the left side of the tank, thereby pulling fuel from the left to right sides. In the engine compartment, there's the supply hose, and the purge hose, which goes back to the evap canister nearby the fuel tank.
 
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