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Starting problems

Tiny
RAMCHARGER
  • MEMBER
  • 1996 CHEVROLET SUBURBAN
  • V8
  • 4WD
  • AUTOMATIC
  • 107,000 MILES
I have a 96 chevy suburban with a 5.7 csfi. It has ac, 4x4, auto tranny. Ive replaced the battery, serpentine belt, plug wires, air cleaner, fuel pump, fuel pump relay, fuel filter. Engine turns over easily. All my fuses are good. I get power to all my injectors. I get 12+ volts to and from the relay, but only 9.4 at the pump harness. Its getting fuel to the check valve. Fuel pressure is at 50/51psi. It did run when I got it around October 2010, but needed starting fluid to get going. Once running, it was fine. What should my next step be? Im pressed for time du to moving, so anything would be helpful. Thank you.
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Friday, February 11th, 2011 AT 4:32 PM

6 Replies

Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I'll double check, but my info says fuel pressure should be 60--66 psi, key on engine off.

If you want to take voltage reading, take reading across battery posts, engine cranking, probably around 9.5volts? Should get close to same reading at fuel pump connector voltage wire for pump motor.
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Friday, February 11th, 2011 AT 4:48 PM
Tiny
RAMCHARGER
  • MEMBER
  • 5 POSTS
Yes, fuel pressure needs to be between 55 and 65 psi to open poppit valve. Im only at 50/51, up from 45 before the repairs. Both battery and fuel pump connector are 9.4 to 9.5. Anything else you know of? Thanks.
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Friday, February 11th, 2011 AT 4:55 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I just told you, your pressure is too low at key on, engine off. After vehicle is running, it can run about 55 psi. It won't start at 55 psi, just my opinion. Does pressure hold when pump stops running?

Pressure regulator, Also, engine cranking, do you have spark at the plugs. Use a noid lite, check for injector pulse.
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Friday, February 11th, 2011 AT 5:25 PM
Tiny
RAMCHARGER
  • MEMBER
  • 5 POSTS
Plenty of spark. Pulse is ok. Pressure rises then drops after initial turn on (3 second prime). Goes up to 50 when cranking, but drops when I stop cranking. Internet said 55 to 65psi to overcome the poppit valve to start truck. Can this be a regulator prob? Can it also be a computer (ecm) prob?
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Friday, February 11th, 2011 AT 6:02 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
I tried to answer your last post, but, it's timing out on me for some reason, don't know why? Don't know if the problem is the site or on my end?
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Friday, February 11th, 2011 AT 6:23 PM
Tiny
JDL
  • MECHANIC
  • 16,098 POSTS
The fuel regulator is a possible issue? Does pressure hold when pump turns off, if it drops like a rock, the first thing I suspect is the pressure regulator.
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Friday, February 11th, 2011 AT 8:47 PM

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