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1998 Chevy Suburban

Tiny
WAYNEBENESKY
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  • 1998 CHEVROLET SUBURBAN
Engine Performance problem
1998 Chevy Suburban V8 Four Wheel Drive Automatic

replaced the fuel pressure regulator now psi is at 51psi when I drive for a while and go to a store and come back out and start the car. Engine lite codes are po173 and po175 rich bank 1 and 2 plus p1404 egr command could this be fuel injector
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Tuesday, April 15th, 2008 AT 7:40 PM

10 Replies

Tiny
MASTERTECHTIM
  • MECHANIC
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Yes. Have a fuel pressure drop test done again.
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Tuesday, April 15th, 2008 AT 7:43 PM
Tiny
WAYNEBENESKY
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Well I have a snapon solus scaner and ran a test with it all the injectors would drop the pressure from 50psi down to 20psi
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Tuesday, April 15th, 2008 AT 8:09 PM
Tiny
MASTERTECHTIM
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You need to pressurize the system and see if the pressure holds. If it does then nothing is leaking. I think your going to find that something is leaking, like possibly a cracked fuel line inside the intake or faulty o ring. Get back to us
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Tuesday, April 15th, 2008 AT 8:12 PM
Tiny
WAYNEBENESKY
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Well the engine is a 7.4 and when I had the upper intake off after replacing the regulator I pressurerized the rail and looked for leaks none should I take the rail out hook up the fuel lines and pressurerise the the rail. When the engine is off pressure and the pump cycles psi will hold for about 20 min then drop then after about an hour it will be down to 20 psi
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Tuesday, April 15th, 2008 AT 8:39 PM
Tiny
MASTERTECHTIM
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If it holds that long then dont look for the leak. If it was that then the pressure would drop off quick. I just looked up fuel pressure and im coming up with the lowest fuel pressure should be 56 psi. What do you have.
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Tuesday, April 15th, 2008 AT 8:52 PM
Tiny
MASTERTECHTIM
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You have a mass air flow sensor. Correct? Try cleaning that. Also how does it run? Consuming oil?
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Tuesday, April 15th, 2008 AT 8:54 PM
Tiny
WAYNEBENESKY
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Key on psi goes up to 60 when pump quits drops to 51 cleaned maf because I was getting code for that awhile back as far as oil one qt between changes 3000mi it runs great way back it was getting codes for low voltage to o2 now those are gone still have the rich codes and the egr1404 and those are the only ones that keep coming back before new regulator psi was low 34psi
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Tuesday, April 15th, 2008 AT 9:15 PM
Tiny
MASTERTECHTIM
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At this oint we need to watch o2 voltages on a scan tool and read other values. Not much more we can do here but pitch parts. Let us know how you make out.
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Thursday, April 17th, 2008 AT 5:22 PM
Tiny
WAYNEBENESKY
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Well I think it might have bad injectors what else could give it rich codes some times it holds pressure over night like 45psi then some times it drops down to 20psi in a hour
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Friday, April 18th, 2008 AT 9:20 PM
Tiny
MASTERTECHTIM
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These injectors are pieces of junk. Replace the whole set with the new style injectors.
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Monday, April 21st, 2008 AT 1:07 PM

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