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Injector leak down rate?

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Old Sep 7, 2014 | 12:07 PM
  #1  
8Mike9's Avatar
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From: Oakdale, Ca
Car: 89 IrocZ
Engine: L98-ish
Transmission: 700R4
Injector leak down rate?

After replacing the FP, I checked the fuel pressure, cycling the key on/off, and pressure would sit and hold at 38 PSI without dropping.
Car still wouldn't start, concluded the injectors were all plugged (had been sitting for years)

Put in a set of Bosch 3's from SB yesterday, bolted the rail down, hooked it up and wanted to check for leaks before assembling the runners, etc.

No leaks around the injectors, but noticed FP dropping about 1lb every 2 seconds till it get's to 10psi.

Seems kinda fast?

I'll call them tomorrow when they are open, just that I don't recall the pressure drop spec, and mu manual only shows balance test spec's.

Thanks.
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Old Sep 7, 2014 | 02:53 PM
  #2  
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From: Milwaukee
Car: 92 Firebird, 77 Trans Am SE, 86 Z28
Engine: 5.7 HSR, T/A 6.6, empty
Transmission: T-5, TH350, T-5
Axle/Gears: 3.08 posi, 3.23 posi, 3.23
I can't quite recall what my bosch 3's dropped at but i seem to remember pressure holding pretty well above 30. I can check mine again if you like but by that time I'm sure you'll have already talked to sb.
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Old Sep 7, 2014 | 03:04 PM
  #3  
8Mike9's Avatar
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From: Oakdale, Ca
Car: 89 IrocZ
Engine: L98-ish
Transmission: 700R4
Re: Injector leak down rate?

Thanks, but not necessary
I'll be able to call them in the morning.
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Old Sep 8, 2014 | 01:40 PM
  #4  
8Mike9's Avatar
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From: Oakdale, Ca
Car: 89 IrocZ
Engine: L98-ish
Transmission: 700R4
Re: Injector leak down rate?

Thought I'd give an update here...no issues with the injectors after all.

I pulled the rails this morning, and bolted them down to another intake laid on top of cardboard, over the intake in the car.

Pressured up a few times, looked for fuel drips..nothing.

Put my gauge on and sure enough...sinking quickly...well that's when I noticed the little bubbles coming out of the pressure release on the gauge..see the hose is old and stained dark, I guess it was too dark for me to noticed the bubbles Saturday evening.

Anyways, pulled the release valve, blew it out, put it back on...goes to 38,,,slowly drops to 30 and sits there forever...I can live with that
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Old Sep 8, 2014 | 02:03 PM
  #5  
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From: Huntsville AL
Car: 88GTA
Engine: 5.7TPI
Transmission: Auto
Axle/Gears: 3.27
Re: Injector leak down rate?

Mike...sounds like deja vu when I did mine. I said WTH, brand new leaky injectors! I t was my gauge also................me
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Old Sep 8, 2014 | 02:26 PM
  #6  
8Mike9's Avatar
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From: Oakdale, Ca
Car: 89 IrocZ
Engine: L98-ish
Transmission: 700R4
Re: Injector leak down rate?

I have a good excuse though...eyesight getting worse, sun was setting, dogs were barking, kids were yelling...yadda, yadda..
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Old Sep 8, 2014 | 04:12 PM
  #7  
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From: Maryland
Car: 1987 IROC-Z
Engine: 5.7 TPI
Transmission: 700-R4
Axle/Gears: 2.73
Re: Injector leak down rate?

So how do she idle now? Did you notice an improvement since you installed the injectors?
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Old Sep 8, 2014 | 04:29 PM
  #8  
8Mike9's Avatar
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From: Oakdale, Ca
Car: 89 IrocZ
Engine: L98-ish
Transmission: 700R4
Re: Injector leak down rate?

I won't get a chance to put the runners and plenum on until Wed.

Thing is, it used to idle fine, so I don't expect any difference,
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Old Sep 14, 2014 | 10:59 PM
  #9  
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From: Maryland
Car: 1987 IROC-Z
Engine: 5.7 TPI
Transmission: 700-R4
Axle/Gears: 2.73
Re: Injector leak down rate?

8Mike9 How is the car running since you change those injectors?
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Old Sep 15, 2014 | 12:33 AM
  #10  
8Mike9's Avatar
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From: Oakdale, Ca
Car: 89 IrocZ
Engine: L98-ish
Transmission: 700R4
Re: Injector leak down rate?

Originally Posted by IROCU2
8Mike9 How is the car running since you change those injectors?
Awesome, the Bosch 3's are a tad noisy/....kinda sound like lifters loose with hood up, but idles sweet as can be.

Don't hesitate to call SBay...good stuff my man
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