I'm usually too proud to ask for help, but I'm stumped, and begging. We bought a non-operable 99 Impreza, thinking I could get it going right away...three weeks ago. It starts, runs for a few seconds, and dies.
I think its a fuel problem:
Initially, I would turn key on, it would pressurize to around 50 psi, then I would hear a 'pop' and pressure would drop to 15. If I started the car, the gage would fly wildly back and forth, but generally start over 40 psi, and drop to 35 psi and the car would die.
I took the pressure gage out of being 'in line' with the rail, and installed it 'dead end' on the line from the pump. It built up to 70 psi, and did not drop. I then took off the return line from the rail, and used my thumb to resist pressure. Again, it would go to 70 psi and hold it. The car would not idle, but it could be revved high and generally would run. From this, I deduced that the fuel pump check valve was holding pressure, and the injectors were not leaking the pressure away....and it was the pressure regulator.
So, I bought one. Now the car runs a few seconds longer before dying, and the gage does not fly around wildly. However, it does the same thing as far as dropping pressure, as the car runs...and there does not seem to be any increase in pressure, if I try to rev the car.
Here's where it get strange. When turning key on, pressure builds up to 50 psi, then I here a 'whoosh' and pressure drops down to 10 psi. I have figured out that the whoosh is fuel leaving the regulator and entering the return line to the tank.
Essentially, the brand new regulator is acting just like the old one. I had assumed that when doing key on, the pressure was supposed to build and 'hold'. Is that correct? Also, I can't find any manuals on this car, so I don't know what the fuel pressure or engine vacuum are supposed to be...does anybody know?
I find it hard to believe that my brand new regulator has failed...so I'm thinking that there must be another problem that makes it look like regulators are bad. One thing I have noticed - the tank never ever has pressure, when I open the cap. Does anybody know if the tank is supposed to be pressurized...and would tank pressure be enough to prevent the regulator from 'popping open' with no engine vacuum.
To all who read this far, thanks for the interest, and any advice would be much appreciated.