You can test the low pressure fuel pump with a fuel pressure gauge. pump running should be around 50-60 psi, then turn off if I remember correctly it should not lose more than 15 psi in 5 minutes.

 

My SS has been sitting for about 4 days. I went out and turned the key on but did not start it. Fuel pressure showed 72 psi which is the pressure from the in tank electric pump.

FYI. The HPFP idle pressures will decrease as the engine warms up. I see around 2200 on cold start up. The warmed up idle pressure is around 450-550.

 

Mine also sits at 72 now that it is all cool. My hpfp also does 2200 ish on cold start up and hangs around 4-600 ish depending if ac is on when warm and idling. Can I test o2 sensors by disconnecting them and seeing if my factory trim fixes itself?
where is the disconnect for upstream o2?

 

If you disconnect the O2 sensor, it will run in an open loop, if I remember the term correctly. Basically it will run on a table rather than adapt to the actual conditions. Puts it into a simple run mode, but won't necessarily determine if your O2 sensor is at fault.

I would be suspect of the O2 sensor and injectors. The injectors basically are open or closed. They work similar to a relay, using an electromagnet to pull a metal piece back and open the injector. A spring closes it. Since your ss was running rich before, it was opening them more often and more frequently, it's possible you burned them out. The fuel pressure while running will be fine and the car shouldn't struggle to start as the hpfp is good and can supply the amount of pressure required. The spray pattern could also be messed up as well.

Have you disconnected the fuel pump fuse and relay and tried to start the car? It should start and run for a while before it will stumble and die if the injectors are good. As for the O2 I think you can use a multimeter to test it, but that may not show it guaranteed.

 

As for fuel pressure, it should be 400 - 600 ish, with a little bit of a fluctuation as the ecu adapts and uses the injectors. Mine falls in correspondence with one cylinder, but I know that's because one cylinder has blowby from carbon build up due to the timing chain. And the piston rings are designed to hold back only so much pressure so if the compression ratio is messed up due to deposits, it will cause some blowby.

Since it was running rich, there is a good chance that the O2 sensor is fouled, however it's trying to lean the A/F ratio as much as possible, so I would suspect that it's the injectors. Pull the fuel pump relay and fuse and try to start the car. If it starts, the injectors are most likely fine. Just seems like more fuel is being dumped into the cylinders than what there should be,even with the new fuel pump and new oil. It could be a valve timing issue still. Only reason I suggest that is because the engine timing is still largely mechanical, with a bit of alteration through the vvt solenoids. Also means the ecu won't be able to detect a problem and throw a code until it's severe.

 

To change the fuel pump out I pulled fuse 13 and 18 or 19 for the fuel pumps and it started right up and ran for a little bit then died. This car has been a bit of a project and I don't know how much you read but it has a different motor and I'm just chasing someone else's problems. To do your test do I need to pull both fuses or just the relay one? I have not replaced maf yet but I did clean it couldn't that be the issue? I just am a little stumped on what's next.

 

Depends on the wiring. The fact that you pulled those fuses and it started is a good sign. If it is stock, with the 2.0 ecotec, it should be fine. The fact it's calling for less fuel and has a code makes it difficult to diagnose, could be the vvt solenoid. Something is allowing too little air, or too much fuel, at least according to the ecu, but it also goes off the sensors so of one is faulty but it doesn't know, it will try to adapt. Honestly try replacing the O2 sensor would be my next guess, guarantees the ecu is getting good data values and makes troubleshooting easier. I have yet to learn the base programming for the ecu or take a look at the circuitry as I don't have issues with mine.

 

Ill buy the o2 and see what happens. Thank you Duck. I am wondering if I am fighting a bad tune or confused pcm because of the new motor. If it has the Buick Regal motor. And from factory the regal motor has 4 bar maps and opel injectors did the new motor come with the regal pcm and is wanted different calibrations of things. Or did it have a tune on old motor and they just threw the new one in with crappy tune just to get rid of it. I will buy o2s and try that first though. Just over thinking stuff.

 

If it’s a new engine, it shouldn’t have carbon buildup in the intake valves.
it should have a new timing chain.
It might have an odd tune, but let’s see what the new O2 sensor does, it should be plugged in on the driver’s side just around the thermostat housing , where the heater hoses connect to the engine.

 

well I guess it could always be a junkyard engine but I hope not.. it does have the zzp powersteering block plate that they install when you buy it from them if its not needed. So I am hoping it is newish. Again. It is all guessing at this point unless the owner shows up and says hey that's my old car this is what I've done. It Does have regal motor though with 6 qt oil pan. Anyone have a diagram of o2 sensors and how they are ran? Easiest way to get to upstream? It looks like up high next to turbo is easiest but there is so much stuff next to it.