2000 Impala 3.8 110k no fuel pressure

cw41

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#1
Hello everyone again, I'm back with troubles with the black cat Impala. The car stalled and would not restart the other night at the gas station so I left it there and returned the next morning and it started and ran fine. I decided that going back with my car trailer and loading it would be the best, started, loaded and unloaded at home and let it run and after about five minutes it died. checked the fuel pressure and it was 0 psi. After 15 years I figured it was the fuel pump which I replaced with a Spectra Premium and also replaced the fuel regulator for good measure. It did not have fuel in the vacuum port but I've read the regulators on these vehicles can cause problems. After all was done, the fuel pump makes noise but no fuel is making to the fuel rail. The fuel filter was changed about 5k ago and the old pump sock was clean and no debris in the tank. My OBD2 shows P0001 fuel volume regulator control circuit open. I cannot find any info on this. I also changed the fuel pump relay with a working one from my 02 and got the same results. Is it possible that I bought a bad new fuel pump?? Any help would sure be appreciated.
 

cw41

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#2
OOps that was the fuel pump relay I changed, not a regulator fuse. Don't know where that come from?
 

kev2

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#3
can you get a different scanner on this vehicle?
there are no other codes- P1xxx and above type?
KOEO - there should be 12v in 2 relay cavities* - yes no?
*check with key in start or within3seconds in run
I believe there is no fuel pressure or relay circuit feedback on this series...
 

cw41

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Unfortunately, I don't have a premium scanner. No codes above p0001 that was it. I have 12v in one pin only on the fuel relay. I cannot find a fuel pressure relay or circuit connected with the new regulator on this impala either. I have three fuse locations on this car and none of them have a fuse or relay related to the regulator. It leads me to believe that I have a wiring issue somewhere. But where to look?
 

kev2

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#6
that is why I asked about another scanner - the code is suspect.

working with what we have - the relay has a 12v fuse source... another 12 v comes from the PCM in start or run* - there is a fixed ground and the switch close circuit will send 12v to pump...

Sorry let me add a diagram - a picture is worth 1000 words,


* circuit will time out if eng not running - RPM CKP signal
 

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cw41

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#8
I rechecked all fuses related to computer and all are good. There is a ignition relay, one of the big fuses, but don't know if this can have an issue or not.
 

The old man

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#9
Looking at kev2 schematic for the fuel pump, you should have 12 volts all the time at b1 of the fuel relay connector block. (even without the key being on). If you take the relay out and jump across b1 and a3, your fuel pump should run and supply pressure at the fuel rail. If not suspect the fuel pump or wiring conections etc. on the fuel pump side. If it does run and supply pressure, will need to look back on computer side to see why you are not getting voltage to b3 from your computer when the engine is in start or run. Might save some time to narrow the search.
 

kev2

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#11
did you look at fuse or check/test it- confirm there is 12v at fuse, both ends AND cavity B1
 

kev2

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#13
NO not returnless,

the old simple tank mounted pump feeds fuel rail, vacuum pressure regulator and a return line.... simple.
even the circuit is simple- PCM energizes relay in run/start-

The reason I am thinking the p0001 is a bad code- my thinking - try another second scanner....
 

cw41

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#14
The old man said:
Looking at kev2 schematic for the fuel pump, you should have 12 volts all the time at b1 of the fuel relay connector block. (even without the key being on). If you take the relay out and jump across b1 and a3, your fuel pump should run and supply pressure at the fuel rail. If not suspect the fuel pump or wiring conections etc. on the fuel pump side. If it does run and supply pressure, will need to look back on computer side to see why you are not getting voltage to b3 from your computer when the engine is in start or run. Might save some time to narrow the search.

I do have 12v at b-1 key on or off. I jumped b-1 to a-3 and the fuel pressure came up to 45psi so this should rule out a bad new fuel pump I just installed. While I still had pressure, I removed the jumper and installed fuel pump relay and started vehicle but it runs rough for a few minutes pressure held at 45psi but not steady. It sounds like its missing or something and I can smell rich exhaust. Can the new pressure regulator be the problem? I used a new ac delco unit. Thanks for the help.
 

kev2

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#15
holds at 45psi running - how does hold when turned off?

drops fast - slowly drops and drops - drops a few and holds steady?