Greetings...
I recently replaced the fuel pump on my 2005 XC70 at 247 k miles because of a P0089 code (fuel pressure regulator A performance) that would not go away. Yet, the P0089 code still persists. This time, the engine hesitates or stalls every once in a while, especially when fuel level is low. New pump is Bosch from FCP. I did not have any lack of power or stalls with the old pump - just the P0089 code!
Prior to replacing the pump, I ran the standard fuel pump test with VIDA and found that the duty cycle remained between 45% - 60% to maintain ~45 PSI at the fuel rail and ~400 kPa on VIDA. All indications were that The fuel pump was at fault to throw the code.
Now, my primary suspect is the secondary pump (I think it's job is to fill up the fuel pump housing bucket). I then used VIDA and activated the "Relay, tank valve" and don't hear any whirring sound coming from the tank. But when I applied 12 volts directly to he secondary pump connection points, I could hear the pump working and also hear liquid noises. I think the engine hesitation and stalls are because the pump bucket is not filling up. Please correct me, add your inputs, etc...
Questions:
- What will cause the secondary pump not to turn on?
- Why didn't I have the stalling problem with the old pump?
I appreciate any help I can get. I've attached a two images from my test.
Thank you in advance
-Kef
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