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  #1  
Old 10-23-2012, 06:54 PM
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Default 94 CPI vortec fuel pressure question

I have been doing work on my fuel system, had a run in with the leaking regulator. First time i installed it it was set to 90 psi. With the fuel pressure at 90 it ran REALLY rich but better than it did leaking. Well i set it to with the pump going engine off at 58psi. Bolted it back up an noticed that in normal operation of key on engine off it's 58psi till it clicks off then drops to 48-50psi. Holds steady, it also runs at 48-50. Idles ok, can feel a miss here and there. 17-18 mpg. Full throttle does good but you feel a bog, actually its more like you dont notice it being sluggish till it kicks in with full power and you can see what you've been missing. Does this randomly while driving but driveable. Is any of this normal? Should i up the pressure setting at the regulator again to 58 after the pump shuts off instead of when pump is running? There are no leaks under the upper plenum (poppets, lines, lines from injector to poppets) made sure of that when i sealed it back up. Maybe my fuel pump is weak from running at 90 psi for so long? Any suggestions? I really just want to know if i set the fuel pressure right or not.
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  #2  
Old 10-24-2012, 08:45 PM
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i would set it to about 60 to 65 psi. have you ever heard of sea foam? it works wonders. you just pour small amounts into the brake booster line. use about a cup worth and when your about finished sucking it all up, just pour it all in fast to kill the engine. if it doest die then hury and shut it off. wait 15 min start then rev to 3 to 4 grand untill smoke clears. it cleans up all the carbon build up and gunk. makes the idle more smooth.

also get some carb cleaner and clean the throttle blade. they get pretty gummed up also and can cause poor idle.
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Last edited by bam_9_9_9; 10-24-2012 at 08:48 PM.
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  #3  
Old 10-25-2012, 06:53 AM
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I have used seafoam before. I cleaned the upper intake out last time i had it off when i did the regulator. I was thinking about raising the fuel pressure a little but my main concern is the fact that when the pump is on i read 58-60 and the second it shuts off it drops to 50 and holds realatively well. Is that normal?
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Old 10-25-2012, 10:31 AM
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I have a video.
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  #5  
Old 10-26-2012, 07:30 PM
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YES thats totally normal. if it holds at 50 or even around 40 for 20 min then its fine. ALL OLD s10 blazers will have a miss now and then. because they use a single injector that fires every compression stroke no mater if the intake valve is open or not. the newer spfi engines like in the 96 blazers or 95 pickups injectors fire only on one intake stroke. fires ONCE per cylinder intake stroke. maby somebody else can clear this up since yea a bottle of vodka goes by quickly in my house. lol. but yea even mine misses a little at IDLE only. when i rev it up its BEAST. but id still turn up the regulator just a few PSI. make it so when it shuts off its around 55 to 50 psi. and when its running make it to where its at 60 psi. dont go above 62psi or lyou might damage the injecor but highly unlikely. also in the video it sounds like you have a vacuum leak. might want to check that out also. go to your parts store and rent a vacuum gauge. leave all the vacuum hoses hooked up and install a t conector in the kit you rented. should be 18psi or close to give or take 2 psi
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Last edited by bam_9_9_9; 10-26-2012 at 07:32 PM.
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Old 10-26-2012, 07:42 PM
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I have fixed all my vacuum leaks long ago, it had about 16-18psi. What you hear is my short ram intake. The filter is about 2 inches from the camera, lol. I had one of those cone filters lying around and slapped it on. I dont think a tad about 62psi fuel pressure will kill it if me running it at 90psi for a month didnt... I'm gonna turn it up and see what happens. Right now if i floor it there is a 50/50 chance it will be sluggish or fast as hell. It's real annoying. Plan on turning it up a few psi this weekend, might push it off a little cause i scored a brush guard for $30. Gotta put it on
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85 Toyota Celica - Sold
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96 S10 ZR2 - sold
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Old 10-26-2012, 09:43 PM
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yea i wouldnt assume its a injector problem. i would like i said tune it to 60 psi. and leave it. i have the ram air intake also if you look at my youtube vids. it sounds pretty cool and i have noticed a bit in low end torque. when running it should be 55 - 60 psi. but when on highway and you hit the gasss all the way it will bog for a sec or two then kick in and bam you will be past them them in senconds. lol
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Old 10-27-2012, 04:56 PM
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Pressure is too low. Bump it up to 60
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Old 10-27-2012, 11:09 PM
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Quote:
Originally Posted by ohsofly View Post
Pressure is too low. Bump it up to 60
This.
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Old 10-28-2012, 10:38 AM
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Ok, but do i set it to 60 while the pump is running or try to get it to 60 after it shuts off? It runs at the psi it drops to after the pump cuts off like in the vid. That's what i'm wondering
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96 Jimmy 2wd - Its back! v8 swap in pregress
94 Jimmy 4x4 - Daily Driver
70 C10 - Sold
98 Blazer 4x4 - Sold
78 Suburban - Sold
99 Bravada - Sold
95 K1500 4.3 5 speed - Sold
85 Toyota Celica - Sold
88 F150 - Sold
96 S10 ZR2 - sold
I'm just goning to stop listing more things as they just keep adding up
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Old 10-28-2012, 10:38 AM
 
 
 
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1994, 43, 94, blazer, clogs, core, engine, exhaust, fix, fuel, heater, lobing, pressure, rick, s10, test, vortec, water, wear


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