Did I find the cause of no start and hesitation?

[somick]

2010 Forester non turbo with 104000 miles.

 

I pressurized the fuel system and pinched the top hose right before the fuel damper and the fuel pressure stayed at 45 psi.  When I removed the pinch pliers the fuel pressure dropped down to zero overnight.

 

So is this my problem for hesitation and no start in the morning?

 

On another hand the excess fuel still needs to go back to the tank during operation.  So the fuel damper is probably set to let the fuel to the tank at some pressure.  Am I right?

 

Is there a way to check the fuel damper operation.  It is more than fifty dollars at the dealer and I do not want to throw money away and replace unnecessary parts.

 

Thanks,

Sam 

[nvu]

The damper rarely fails, on a 2010 I doubt it's the culprit.  You could get away with removing it completely and bridging the lines.

You're describing the fuel pressure regulator, it's near the injectors and has a third port that goes to a vacuum hose.  Unplug the vacuum hose while the engine is running.  It should not have fuel coming out. 

Fuel pressure probably doesn't hold overnight,  but it should hold for a couple minutes right after key off.

[somick]

1 hour ago, nvu said:

The damper rarely fails, on a 2010 I doubt it's the culprit.  You could get away with removing it completely and bridging the lines.

You're describing the fuel pressure regulator, it's near the injectors and has a third port that goes to a vacuum hose.  Unplug the vacuum hose while the engine is running.  It should not have fuel coming out. 

Fuel pressure probably doesn't hold overnight,  but it should hold for a couple minutes right after key off.

Thanks nvu.

 

It does make sense.  According to YouTube the FPR is located on the passenger side of the engine but I could not find it.  However there is a device mounted on the driver side  which has tow tubes connected to it.  I will have a closer look tonight.

 

Sam

[Rampage]

Try turning the key on and listen for the fuel pump to run and stop, turn the key off then back on and try to start it.

The Fuel Pressure Regulator bolts on to the end of the fuel rail that the injectors are connect to.

https://www.partsgeek.com/catalog/2010/subaru/forester/fuel_injection/fuel_pressure_regulator.html

The small hose is vacuum as stated by nvu. The large hose is the return to the fuel tank.

On our 95 and 97 Legacy's I hook a pressure gauge between the fuel filter and the engine with a tee. According to the factory service manual, with the engine running normal psi is 30, disconnect the vacuum from the regulator and it goes to 38 psi. I found that ours normally run about 36 psi. If I pinch the return line the pressure jumps to 80 psi which tells me the pump is really working good.

The fuel pump has a check valve to hold pressure. Our cars have sat for days and still have pressure in the lines.

A few years ago the 95 was having a rough time with hills. After checking a bunch of stuff, I hooked up the gauge and pinched the return line and the pressure would not go above 36 psi. I put in a new fuel pump and my wife got her car back. Chirp the tires on 1 -2 shift.

[somick]

On 9/3/2019 at 8:58 PM, Rampage said:

Try turning the key on and listen for the fuel pump to run and stop, turn the key off then back on and try to start it.

The Fuel Pressure Regulator bolts on to the end of the fuel rail that the injectors are connect to.

https://www.partsgeek.com/catalog/2010/subaru/forester/fuel_injection/fuel_pressure_regulator.html

The small hose is vacuum as stated by nvu. The large hose is the return to the fuel tank.

On our 95 and 97 Legacy's I hook a pressure gauge between the fuel filter and the engine with a tee. According to the factory service manual, with the engine running normal psi is 30, disconnect the vacuum from the regulator and it goes to 38 psi. I found that ours normally run about 36 psi. If I pinch the return line the pressure jumps to 80 psi which tells me the pump is really working good.

The fuel pump has a check valve to hold pressure. Our cars have sat for days and still have pressure in the lines.

A few years ago the 95 was having a rough time with hills. After checking a bunch of stuff, I hooked up the gauge and pinched the return line and the pressure would not go above 36 psi. I put in a new fuel pump and my wife got her car back. Chirp the tires on 1 -2 shift.

Thanks Rampage.

 

There is no (or I cannot find the traditional FPR).  There is Fuel Pressure Solenoid.  I can tell that it works fine since the fuel pressure is kept at 50 psi with very little fluctuation. 

 

Since the fuel pressure drops very fast after I remove the pinch pliers I bit the bullet and ordered a new fuel damper from the dealer for seventy dollars.  It should be here soon.  I am going to install it and see what is going to happen.

 

Thanks,

Sam