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Username Post: 93 C1500 5.7 fuel pump or regulator        (Topic#354802)
Sabino 
Member
Posts: 44

Reg: 07-16-05
01-11-19 07:17 AM - Post#2757108    

I measured 8 psi with actron in line adaptor after fuel filter on a 93 5.7 TBI C1500. I have read it should be at least 10psi.
Is there a way to tell if it's pump or regulator? It seems regulator is set by spring so it's active all the time.

background
I replaced the fuel pump about a year ago when replacing the fuel sending unit. I hadn't ordered a fuel pump so just picked up one from Autozone. I didn't replace filter at the time. I meant to drive it a bit and then replace filter but forgot.
Recently, I had some stalling/hesitation/hard shifting and replaced the filter & knock sensor (had transient code on it). Drives well now - but when I measured fuel pressure it's lower than it should be.
I'm trying to decide if I should just drop tank and put in an ACDelco pump or attempt to troubleshoot the pressure regulator. It seems easier to drop tank/replace pump than get into the TBI?
thanks in advance for any advice/suggestions



65 Belair 350
68 Camaro 327
85 Caprice 5.0L
93 Suburban 5.7L TBI


 
1983G20Van 
Super Senior Member
Posts: 3737

Loc: Bedford, Texas, USA
Reg: 11-13-02
01-11-19 07:27 AM - Post#2757110    
    In response to Sabino

  • Sabino Said:
I measured 8 psi with actron in line adaptor after fuel filter on a 93 5.7 TBI C1500. I have read it should be at least 10psi.
Is there a way to tell if it's pump or regulator? It seems regulator is set by spring so it's active all the time.

background
I replaced the fuel pump about a year ago when replacing the fuel sending unit. I hadn't ordered a fuel pump so just picked up one from Autozone. I didn't replace filter at the time. I meant to drive it a bit and then replace filter but forgot.
Recently, I had some stalling/hesitation/hard shifting and replaced the filter & knock sensor (had transient code on it). Drives well now - but when I measured fuel pressure it's lower than it should be.
I'm trying to decide if I should just drop tank and put in an ACDelco pump or attempt to troubleshoot the pressure regulator. It seems easier to drop tank/replace pump than get into the TBI?
thanks in advance for any advice/suggestions





The TBI is very easy to get into and the regulator springs tend to corrode and snap in half.

1983 G20 Van, 350 TPI, Ported 906 Vortecs, Edelbrock 3817 Base, ASM oversize runners. Reed Custom Roller cam, 700r4, 12 bolt with 3.08 gears, Doug Thorley Tri-Y headers, true duals


 
bowtie44s 
Valued Contributor
Posts: 4112
bowtie44s
Age: 36
Loc: wv
Reg: 08-29-12
01-11-19 08:25 AM - Post#2757114    
    In response to Sabino

Autozone's house brand is pretty poor quality. You should either use an AC Delco or Delphi pump. I prefer Delphi but it is now made in China as well so flip a coin. I would change the fuel filter and check again, but I would suspect the pump. 9-13 psi is spec, but a new pump should give you 12-13.

It's personal preference,but I find it way easier to unbolt the bed and slide it back a foot than drop the tank. It's 8 bolts that you can get with an impact and it doesn't matter how much fuel is in the tank. You're also working on the pump at waist level.

Jeff

'88 Chevy K3500, aluminum head roller cam 511inĀ³ stroker 10.5:1 compression, 96 NV 4500, 94-98 grille, 305/70-16 (33x12) BF Goodrich KM2s, 91 cluster swap


 
Sabino 
Member
Posts: 44

Reg: 07-16-05
01-11-19 05:02 PM - Post#2757149    
    In response to bowtie44s

Thanks for replies. I have a Suburban so unfortunately it's a drop of tank.
I'm thinking I'll plan on doing both. It has a bit over 200k miles and I've never touched the TBI. I see there is a gasket kit on RockAuto by ACDelco so it won't hurt to clean it up and replace gaskets, etc. I'll get a pump at the same time and do that right away if the TBI doesn't fix it - and when I get the time if the TBI does fix it.

65 Belair 350
68 Camaro 327
85 Caprice 5.0L
93 Suburban 5.7L TBI


 
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