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Fuel pressure 2006 3.0R


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23 replies to this topic

#1 screwbaru2

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Posted 19 September 2017 - 01:36 PM

Could someone please tell me the fuel pressure at idle for a 3.0R?  Is it the same as the 2.5?  I think I have a bad pressure regulator but I can't be sure w/o the knowing the correct pressure.  I've looked for the answer here and other places w/o success.



#2 golucky66

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Posted 19 September 2017 - 02:16 PM

Spec for fuel pressure using a 2006 Outback 3.0L as a reference car is:

48-53 without pressure regulator vacuum hose.
40-45 with it connected.
Fuel pump shut off discharge pressure is 80-125 psi.

#3 screwbaru2

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Posted 19 September 2017 - 02:44 PM

Thank you very much.  The regulator is good!  I get 45psi on the nose w/hose connected and 55psi disconnected.

 

 That's $300.00++ I don't need to spend! 

 

It leaks down overnight to less than 10psi and won't start without excessive turning.  A count to 3 after turning the key on, will produce a quick start.

 

Any ideas?



#4 golucky66

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Posted 19 September 2017 - 03:04 PM

It leaks down by 10 psi or leaks down TO 10 psi?
If it leaks down to 10 psi you have a leaking injector most likely (or a slowly leaking regulator) and the low fuel pressure is the reason for the extended crank.

If it leaks down by 10 psi i wouldn't worry about it

#5 golucky66

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Posted 19 September 2017 - 05:07 PM

So typically if it leaks down it isn't always an issue. It could leak down to 0 psi but provided there's still fuel in the entire system (rail included) the pressure should skip up immediately when key is turned on.

What i would do is leave the pressure gauge hooked up over night. See what it drops down to.
Then in the morning turn the key on and see what the gauge does.
If it very slowly or not at all (right away) climbs in pressure, you might have an issue with the pump itself ir the check valve.

But if you turn the key on, pressure immediately spikes to 45 psi, and it still has a long crank. You can probably rule out fuel as an issue.

#6 Fairtax4me

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Posted 19 September 2017 - 06:31 PM

Thank you very much. The regulator is good! I get 45psi on the nose w/hose connected and 55psi disconnected.

That's $300.00++ I don't need to spend!

It leaks down overnight to less than 10psi and won't start without excessive turning. A count to 3 after turning the key on, will produce a quick start.

Any ideas?


How quickly does it build pressure when you turn the key to start? If pressure build is slow the fuel pump is going out.

#7 screwbaru2

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Posted 19 September 2017 - 07:06 PM

It builds up right away, by the count of 3 it has already peaked to 45psi. Turning the key to start after the counting to 3 with key on produces a quick start.

When the key is turned to start right away it takes about the same count to 3 while turning the engine before it starts.

I already put a gauge on it over night that's how I know it leaks down over night to less than 10 psi.

I'm going to put the gauge on my 2004 3.0 that starts right up and see how much that system drops overnight.

So far I've read that leaky injectors may set a code and EVAP leaks will set a code. So neither one is likely for leaking down as no codes are set.

It really isn't a big issue as a simple count to 3 with the key on and it starts right up. I'm concerned that it may get worse and possibly strand my wife again.

We aren't too fussy about cars, we do however draw the line at getting stuck on the side of the road too often. We both have a 50+ mile 1 hour drive to work so we need reliable machines. I try to make sure everything is right with both cars. Something is wrong with that 2006. I'd like to find out what so I can decide whether she can live with it or I need to fix it.

Thank you to everyone that has responded. I usually need all the help I can get.

Edited by screwbaru2, 19 September 2017 - 07:09 PM.


#8 golucky66

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Posted 19 September 2017 - 07:11 PM

Based off of all that info, my guess would be a combination of a weak fuel pump and or the check valve is leaking a little. But it seems a fuel pump is weak.

#9 1 Lucky Texan

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Posted 19 September 2017 - 10:04 PM

pull plugs in the morning to look for a wet one? leaking injector if found.



#10 Mike104

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Posted 20 September 2017 - 11:52 AM

I usually turn my key to ON and wait until the fuel pump shuts off before I start my car.  Works everytime.



#11 screwbaru2

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Posted 20 September 2017 - 05:02 PM

Ever do plugs on an 3.0?  By the time I got them all out they'd be dry!  Last time it took 4 hours to do the plugs.

 

Mike104 that works every time on this car too.  It should not be nessarcy for a quick start. 

 

The system should be pressurized.  That's why there  is a procedure to relieve the pressure.  It's a closed system a small pressure drop is fine but not below 10psi on a 45psi system.

 

golucky66, I doubt the pump is weak as it is at the max pressure.  A check valve was my thought too.  There are a couple of fuel dampers that could leak also. 

 

Thanks all



#12 golucky66

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Posted 20 September 2017 - 05:55 PM

While i agree the pump isn't isn't the primary issue. It could be weak causing the delayed start to be worse then it would be.

You can have pressure without the adequate volume.
So sure it gets to spec, but it might be working harder then it should because it's having a hard timing filling the lines with fuel.

But if while it's running you're not experiencing running concerns above 4k rpms the volume is likely fine. Almost certainly ruling out tight pump itself.

At this point. It seems like there's a leak somewhere. Injector, check valve, or external leak. Just got to find it

Edited by golucky66, 20 September 2017 - 05:56 PM.


#13 Fairtax4me

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Posted 20 September 2017 - 10:11 PM

Fuel pump is going out. Pressure should build instantly. Before you can count "One" it should be at max. Once at pressure these pumps will tend to maintain pressure for the most part. Eventually that delay will turn into 5-10 seconds, and then the pump will not build pressure at all.
Check valve possibly, but that's part of the pump.

#14 screwbaru2

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Posted 27 September 2017 - 10:21 AM

So the car has been back up and running for almost a week now.  It runs fine doesn't seem to be starving for fuel at any RPM.  The issue seems to be intermittent, so now with that and after reading Fairtax4me's post I'm coming around to suspecting the fuel pump.

 

The car was down over the weekend to replace the coolant return pipe on the left side of the engine.  What a bear!  Had to cut the new pipe in half to install it then re-connect it with a piece of hose and clamps.  While I was there I noticed the oil cooler pipe in front doesn't look too good either, not leaking like the return pipe but soon it will.  I'm glad it just got hot enough for my wife to notice but not damage the engine.  I lost a 3.0 that way last year.  IMO those pipes should have been aluminum not steel.

 

Subaruparts4you.com  lists the  fuel pump check valve separate so it's probably replaceable.  However if I'm going to handle an 11 year old fuel pump it's going to be to replace it!

 

I'm going to keep an eye on it for awhile see if the pressure drops, the issues gets stable that is not intermittent, or the time to max pressure gets longer.  If any of those things happen or some other issue develops that seems fuel related my 1st suspect will be the pump.

 

Thanks again everyone for the input it was very helpful.  Always good to get outside advise from smart people.  Sometimes I get fixated on one thing and can't see past it, other ideas help to make me think differently.

 

What does a bad driveshaft center bearing sound like?  This car has a rumble in the rear that is not bearings or shocks or bushings.  It happens with or without acceleration, coasting in N produces the same rumble as accelerating up a hill.  It's been doing this for a few months now without change, it doesn't get worse or break just keeps rumbling.   Got new tires and alignment because it needed it, but the noise didn't change.  No worn or broken parts were found.

 

Any ideas on this one?



#15 1 Lucky Texan

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Posted 27 September 2017 - 10:56 AM

sure it isn't a wheel bearing?

 

there's half a dozen ways Subaru wheel bearings can fail. worth checking for. Get the rear in the air, use a mechs stethoscope and listen to each side for comparison as you turn the wheel. Feel for vibration on the coil spring, lift/rock in the 12 -to-6 oclock direction too. should be no movement - not even 2mm.

 

 

you could try FWD fuse , if that makes a difference, could be an issue with the wet clutch pack I guess. Any bucking/jerking in tight parking maneuvers?


Edited by 1 Lucky Texan, 27 September 2017 - 10:58 AM.


#16 Fairtax4me

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Posted 27 September 2017 - 03:18 PM

A deep rumble/wobble sensation from the center/rear of the car is usually a bad u-joint on the driveshaft. They don't normally have play, you have to unbolt it from the rear diff and check to see if the u-joints are seized.

#17 screwbaru2

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Posted 29 September 2017 - 06:52 AM

Both the tire service station and I have checked the wheel bearings there is no play or noise.   The 3.0L equipped cars don't provide the option of FWD unfortunately.

 

I tried shaking/bouncing the driveshaft for play but didn't think about seized joints.   I would think that a seized u-joint would have broken after a few months.   I've seen more than a few grenade in my lifetime. 


Edited by screwbaru2, 29 September 2017 - 06:58 AM.


#18 Fairtax4me

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Posted 29 September 2017 - 07:52 AM

These can explode if left to wobble for long enough. Several threads here about shredded transmission tail housings and damaged shift linkages/broken shift cables from u-joints breaking.
The ujoints on these have a very narrow operating angle compared to most RWD vehicles, Only about 1-2 degrees, So they can seize and still allow the driveshaft to rotate.

Typical symptoms of a bad ujoint still apply. Rumble/vibration that starts around 35-40mph and gets much worse around 70-80mph. Could have a rumble/wobble sensation at low speed during hard acceleration.

#19 1 Lucky Texan

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Posted 29 September 2017 - 07:52 AM

Any bucking/jerking in tight parking maneuvers, or tight circles on dry pavement?

#20 idosubaru

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Posted 29 September 2017 - 08:01 AM

Noise - front/rear, left/right, center/back/front?  

Sit in the back while someone drives it with your ear to the floor - you'll be able to tell if it's center or left right.  

 

Ujoint: 
Grab and shake/pry with a long tool.  Any play and it's bad. 

They can also seize tight such that you can't diagnose them on the car.  They seem rigid enough but not until the shaft is removed do you see that one of the joints doesn't move at all.  You can attempt o run it on a lift (disclaimer - you could die) and watch for movement, or carefully inspect each joint and look for shiny metal or a yoke out of alignment. 

 

Wheel bearing: 

Checking for play in bearings these days is almost a waste of time and often makes people think their bearings are fine, when they are not. Maybe 1/3 or less of the bad Subaru wheel bearings I've seen have play in them. Usually they do not.  They have noise - with zero play, and often times turn smoothly by hand, making them difficult to diagnosis. 



#21 Gloyale

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Posted 29 September 2017 - 05:22 PM

I usually turn my key to ON and wait until the fuel pump shuts off before I start my car.  Works everytime.

 

It should not be nessarcy for a quick start. 

 

 

Actually.  You are supposed to turn the key to "on", pause long enough to see all the indicator lights "prove" themselves and systems are ready.

 

THEN you start the engine.

 

Ripping the key right to start is hard on the contacts and gives a quick voltage spike/drop cycle to the ECM every single time you do it.

 

I am not saying that you might not have a fuel pressure issue.  It could also be MAF issue or just clogged air filter.  That woudl be the difference you notice between cars.

 

But you should as a matter of practice turn key on, pause for CEL and other warning lights, then start.  On any car.



#22 screwbaru2

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Posted 01 October 2017 - 04:39 AM

No, but after reading the post after yours it's clear to me that the driveshaft as to be removed for inspection.

 

Gloyale, sounds logical, good advise.  thanks

 

Back to the rumble, I have sat in the back seat and listened to the noise.  When sitting on the left it sounds like it comes from the right when sitting on the right it sounds like it's on the left, hence my thought about the center bearing.

 

Sounds like for wheel bearings diagnosis I need to be a fortune teller not a mechanic.



#23 1 Lucky Texan

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Posted 20 October 2017 - 08:57 AM

any success finding the problem?

#24 1 Lucky Texan

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Posted 08 December 2017 - 11:40 AM

bump




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