Ls1 won't start/ just replaced fuel pump

[Bigjames25]

98 camaro z28 ls1 won't start after replacing fuel pump. I had a cheap ebay pump that I replaced with a Walbro 255lph pump along with a new fuel pressure regulator and fuel tank pressure sensor. While trying to start the car I can hear the fuel pump priming and the pressure reads at just a little over 70lbs. I know the ls1 usually runs around 60lbs of pressure so could to much pressure be flooding the engine and stop it from turning over? I don't think so but I would appreciate any input. Thank you!

[Bigjames25]

A code did come up at first. P0452 evaporative emission control system. After I cleared it, it never reappeared.

[pajeff02]

Does it try to start, or just crank and crank?

[Bigjames25]

Does it try to start, or just crank and crank?

I believe it's just cranking and cranking because it's getting 70lbs of fuel pressure and the whole engine is cranking trying to turn over but it won't.

[pajeff02]

I guess you need to start by addressing the excessive pressure. I have found out on several occasions that "new parts" do not always mean "good parts". If you have a second fuel pressure gauge you can get your hands on, use that to verify the 70 psi reading before you go ripping into things. Should be able to rent or borrow one from a chain parts store if you don't have a friend with one handy. I am uncertain what effect the excessive pressure would have has the PCM will adjust injector pulse width in accordance with pressure and voltage. Probably has an upper limit to what it can handle though. Maybe pull a plug or two and see if they are getting washed down with excessive fuel.

[Bigjames25]

I guess you need to start by addressing the excessive pressure. I have found out on several occasions that "new parts" do not always mean "good parts". If you have a second fuel pressure gauge you can get your hands on, use that to verify the 70 psi reading before you go ripping into things. Should be able to rent or borrow one from a chain parts store if you don't have a friend with one handy. I am uncertain what effect the excessive pressure would have has the PCM will adjust injector pulse width in accordance with pressure and voltage. Probably has an upper limit to what it can handle though. Maybe pull a plug or two and see if they are getting washed down with excessive fuel.

I held the pedal to the floor and the car started but the rpms were really high in park. I think it was around 2300-2500 rpms. And then the codes P0121 & P0123 came up. They're for the throttle/pedal position sensor.

[pajeff02]

You certainly have something weird going on. Were you able to verify the 70 psi reading? Any other work done when the pump was replaced -- ie. hotwire kit for the pump?

[jb3golf]

70 doesn't sound right at all.....sounds like something else wasnt plugged in correctly or a voltage/wiring issue within the pump assembly...so did you figure this out?