Fuel Problem Help - Regulator/Pump/Pressure/Electrical?

I have been banging my head on the wall about my fuel pressure . In the last week I have twice replaced the fuel pump with a new one and both times got the car to fire up and drive perfectly for about a mile. After that it choked and died. Then I went back and put the OEM pump back in and it did the same thing.

I am only getting about 5-10psi of fuel pressure at the rail which leads me to think either fuel pump or pressure regulator. I am leaning towards the pump/assembly. I just bought the whole pump assembly for about $300 because 1) every time I replace just the pump the car works so it makes me think it is something related to that piece, 2) my fuel gauge does not keep accurate reading & the sending unit was tested bad, 3) my low fuel warning light does not turn on (it is also wired through the sending assembly).

I hope this is the right move. I ordered it online but haven't received or installed yet. Maybe you have suggestions?

My one concerns is my voltage at the pump. I did already replace my relay and am getting about 11.57 volts to the pump . Is that enough to fully power the pump and get full pressure? My pump turns on (audibly) and runs (fuel is moving to the motor). But, I have read that the volts need to be at 12v at the pump. Is 11.57v too low? Or sufficient?

Any help would be appreciated! Thanks!

I would think 11.57 would run the pump at more than 5-10 psi. it is getting 11.57 with the car off. this would jump greatly to above 12v if the car did start due to the alternator pushing the main voltage to 13.5+-. If you want to see 12 volts at the pump simply hook a battery charger to the vehicle to raise your battery source voltage.

Have you changed the fuel filter yet? they can and do get clogged and cause a restriction.

and during the pump installs did you get all the o-rings on? this is a similar thread although much newer legacy where that was found to the be the issue. http://legacygt.com/forums/showthread.php/fuel-pump-fuel-pressure-regulator-214505.html

Thanks for the response. I don't believe my pump/assembly has an o-ring. I never noticed one when removing the OEM or when re-installing it.

However, I ended up taking the car in to the shop. The problem started when the car wouldn't start after parking after a 45 minute drive. No warning signs, no CEL, nothing. Just all of a sudden wouldn't start. Since then I have litterally checked everything. The sparks and injectors are good, fuel filter is new, cleaned the fuel rails, the injectors, the plugs, checked every connection and ground, replaced the fuel pump relay with OEM, replaced pump 3 times, (Twice with brand new ones) Checked the voltage drop to the pump, checked the voltage at the pump, cleaned the fuel lines, Removed, inspected and cleaned the Fuel pressure regulator, checked every sensor for a complete circuit with correct resistance, checked the distributor, and cursed a heck of a lot.

All in all I still did not rectify why the car wouldn't start. Except yesterday, as I decided to check the electrical resistance connection from the pump all the way through to the connection under rear seat the car did a miracle. I had removed the pump assembly, and checked everything, re-installed, and decided to try it. As with the previous two times I had removed and installed the assembly, the car started right up. Only this time it drove for about 5 miles all the way to the shop.

Still no idea what is giving it these intermittent problems or why it wouldn't start in the first place.

As it sits it has a brand new filter bag attached to the pump, a new fuel pump relay (OEM), and some cleaned parts. Nothing else has been done.

We will see what the shop says.

It ended up being the terminal connection to the fuel pump. Unfortunately Subaru does not sell pigtail connections, only the entire wiring harness, so I made a trip to the junk yard. I found a connection and the entire fuel pump assembly in nearly mint condition. The assembly is still shiny, clean, and looks basically brand new. Got them all for only $40. Had the shop wire up the pigtail terminal, plug it into the fuel pump assembly already installed in my car, and now it works great! And I have a basically new fuel pump assembly sitting in my garage just waiting if I ever need it.

Thanks again for all your help!