I have been searching and reading ALOT of posts here about SC's having hard hesitation when over 5psi boost at WOT. I now have this problem. I have diagnosing this for over 2 months on mine, and at some points I had thoughts of getting out of the SC period. But I stuck to my guns, and after replacing just about every electrical sensor/ignition part on this thing (including wires/plugs), I finally get the urge to move on to fuel system. I connect a FP meter to the schrader valve on the fuel rail, and read it as I drive. Here's what I found;
idle pressure = 37-40psi
0 to 5psi boost = 40-45psi
past 5psi at any rpm = 20-22psi
in other words, when I floor it, the meter goes up to 45psi until boost goes past 5psi, then it drops immediately to 20psi.
I know this means fuel pressure reg or fuel pump, but how can I tell which one?
It's not likely that the fuel pump would just drop like that at the same point each time would it? Besides the fuel pump is a recent install (190lph). I even put a jumper across the inertia switch in the trunk just to make sure it was not a continuity problem there- but it did the same thing.
When the fuel pressure reg is in vacuum at idle, is it supposed to limit the fuel to 35-40psi, and when you go WOT with no vacuum it lets more pressure thru at 50-55psi assuming 15psi of boost? I tested this with the FPR vac unplugged, and it still nosed over at WOT at the exact same point. Could this mean that it's not the FPR?
I'm thinking a fuel filter or crimped line would not do this because it suddenly drops pressure rather than gradual. One thing I did notice is that when I unplug my alternator the fuel pump sped up slightly- I even checked that and it's reading 14 volts which is good.
The car idles and drives perfect until you try to get on it over 5psi boost. Very weird.
I don't get this at all- sorry about all the crazy questions, but I am inviting any and all opinions here. Maybe we can settle this problem once and for all on the SC- I know alot of you out there are having the same issues.
idle pressure = 37-40psi
0 to 5psi boost = 40-45psi
past 5psi at any rpm = 20-22psi
in other words, when I floor it, the meter goes up to 45psi until boost goes past 5psi, then it drops immediately to 20psi.
I know this means fuel pressure reg or fuel pump, but how can I tell which one?
It's not likely that the fuel pump would just drop like that at the same point each time would it? Besides the fuel pump is a recent install (190lph). I even put a jumper across the inertia switch in the trunk just to make sure it was not a continuity problem there- but it did the same thing.
When the fuel pressure reg is in vacuum at idle, is it supposed to limit the fuel to 35-40psi, and when you go WOT with no vacuum it lets more pressure thru at 50-55psi assuming 15psi of boost? I tested this with the FPR vac unplugged, and it still nosed over at WOT at the exact same point. Could this mean that it's not the FPR?
I'm thinking a fuel filter or crimped line would not do this because it suddenly drops pressure rather than gradual. One thing I did notice is that when I unplug my alternator the fuel pump sped up slightly- I even checked that and it's reading 14 volts which is good.
The car idles and drives perfect until you try to get on it over 5psi boost. Very weird.
I don't get this at all- sorry about all the crazy questions, but I am inviting any and all opinions here. Maybe we can settle this problem once and for all on the SC- I know alot of you out there are having the same issues.
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