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1997 Chevy Truck Low fuel Pressure Chevy K1500 CSFI system

Tiny
PILONA42
  • MEMBER
  • 1997 CHEVROLET TRUCK
  • V8
  • 4WD
  • AUTOMATIC
  • 238,000 MILES
Pulling my hair out. Trying to fix a low fuel pressure problem. I have replaced everything. Fuel filter, fuel pump, fuel pressure regulator and she still runs at 55 lbs. (Book says 60-66 for my truck). Im confused because when I cycle the key on the pump runs at 64 then when I start it she drops the 55. Does anyone have any ideas? (Please dont say spider)
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Friday, February 26th, 2010 AT 9:55 PM

11 Replies

Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
Is it a electronic modulated regulator or do you have a vaccum type? The spec your getting is that key on engine off? Engine running spec? Engine running unregulated spec?
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Saturday, February 27th, 2010 AT 9:19 AM
Tiny
PILONA42
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Its a vacuum regulator located on the spider injection unit itself and I replaced that yesterday. It has pressure when I cycle the key on but when I start it she drops to the 55lbs
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Saturday, February 27th, 2010 AT 11:36 AM
Tiny
BLACKOP555
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Pull off the vaccum line. Does pressure go in specs then?
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Saturday, February 27th, 2010 AT 4:59 PM
Tiny
PILONA42
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  • 13 POSTS
This truck has the CSFI system and the regulator is inside the upper intake.
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Saturday, February 27th, 2010 AT 5:38 PM
Tiny
BLACKOP555
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Ok my specs are showing 55 is good if vehicle is running. When the vaccum is put on it the pressure will drop to help with economy and prevent engine from running rich and flooding or polluting too much.
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Sunday, February 28th, 2010 AT 12:16 AM
Tiny
PILONA42
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Thanks for that info. So where do I go from here? I purchased a scan tool but not sure what to do with it to find the cause of my multiple cylinder misfire error code.
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Sunday, February 28th, 2010 AT 12:20 AM
Tiny
BLACKOP555
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With your scan tool you can look for freeze frame data and see if anything looks awry. Whats the resistance on the spark plug wires?

When did this occur first? Do you notice the miss? When does miss occur
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Sunday, February 28th, 2010 AT 7:53 AM
Tiny
PILONA42
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You can hear it missing at idle but when you put it in gear it barley wants to run. Really bad! This all happend when I installed a new distributor. I disturbed the motor and took it in to have the cam retard set and still runs like crap. I will check the freeze frame data and get back to you with what data I find.
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Sunday, February 28th, 2010 AT 10:48 AM
Tiny
BLACKOP555
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So thats when it happened. Why was dist replaced?

Try setting the base timing yourself and see how it goes. Maybe they didnt disconnect the spark advanced. Could really be screwing up bad if the spark timing is off a decent amount.

Make sure you remove the spark advance and the engine is warm
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Sunday, February 28th, 2010 AT 10:05 PM
Tiny
PILONA42
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The distributor was replaced because one of the tabs for the dist. Cap screw was broken and the cap wasnt seating properly. I was always told that the ignition timing cannot be adusted.? Im so frustrated!
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Sunday, February 28th, 2010 AT 10:20 PM
Tiny
BLACKOP555
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When new dist was put in it had to be put in IDENTICAL to how the old one was. If not you will have the timing be off quite a bit just by putting the tooth one tooth off.
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Tuesday, March 2nd, 2010 AT 5:51 PM

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