92 Z28 5.7 won't start, help needed

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Feb 10, 2020 | 02:57 PM
  #1  
Hello,

I'm new to the forum, I bought a 92 Z28 which had been sitting for some time. I can't get the car started. I'll be as specific as possible, I've done a lot of reading here and have learned a lot. Please help.
first of all, I have spark and fuel, I replaced the following parts:
plugs and wires
Dist cap and rotor
Ignition Control Module
New fuel tank, new fuel pump and new sending unit and new fuel filter.
what I've done:
Checked for spark on all cylinders
Check the ignition coil, its good.
Measured fuel pressure, read out 43 PSI when cranking and 50 PSI when ignition is on. I can hear the fuel pump pumping.
I checked that there is gas at the engine bay (before the throttle body) but I have not measured fuel pressure there.
The engine starts with starting fluid .
There is 12 volts at the ignition coil.
what I haven't done:
Checking the fuel rails and injectors
Checking the fuel regulator (I did check for leaks, and there are none according to the fuel pressure gauge). The pressure does not drop to 0 after turning off the key.

I dont know what else to do besides checking the injectors. Any tips at this point?

Thank you
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Feb 10, 2020 | 03:42 PM
  #2  
Re: 92 Z28 5.7 won't start, help needed
Have you checked for a injector pulse signal with a noid light ?
if the injectors are old and have been sitting with fuel in them they are varnished and trash.
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Feb 10, 2020 | 04:27 PM
  #3  
Re: 92 Z28 5.7 won't start, help needed
Quote: Have you checked for a injector pulse signal with a noid light ?
if the injectors are old and have been sitting with fuel in them they are varnished and trash.
Thanks. I haven't done any work around the injectors yet. I can check pulse with a voltmeter, correct? No need to take them out?
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Feb 10, 2020 | 04:45 PM
  #4  
Re: 92 Z28 5.7 won't start, help needed
You can only check for power to the injectors with a vom.
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Feb 15, 2020 | 05:11 PM
  #5  
Re: 92 Z28 5.7 won't start, help needed
Quote: You can only check for power to the injectors with a vom.
ok, I had a chance to take off the injectors today. Six of them tested at 16, one at .09 and there is one I'm not getting any reading on. I'm assuming those two are bad not to mention the rest are probably clogged anyway. I'll be replacing them all. I also noticed the vaccum hoses need to be replaced.
Any advice on injectors? I saw some Bosch remanufactured ones on ebay with lifetime warranty, thoughts?
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Feb 15, 2020 | 05:48 PM
  #6  
Re: 92 Z28 5.7 won't start, help needed
southbay fuel injectors has 22#hr in b3 and Delphi’s.
some say the b3s nerd tuning and will run lean. You would have to datalog to confirm.
the Delphi’s should be a direct replacement.
If you go super cheap and get eBay injectors they may not have the correct voltage offsets to be a direct replacement. If they are used you don’t know how well they flow.
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Feb 15, 2020 | 08:47 PM
  #7  
Re: 92 Z28 5.7 won't start, help needed
Quote: southbay fuel injectors has 22#hr in b3 and Delphi’s.
some say the b3s nerd tuning and will run lean. You would have to datalog to confirm.
the Delphi’s should be a direct replacement.
If you go super cheap and get eBay injectors they may not have the correct voltage offsets to be a direct replacement. If they are used you don’t know how well they flow.
Thanks. I placed an order for some 22lbs injectors from Southbay. Hopefully this will get the car started.
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Feb 23, 2020 | 10:04 AM
  #8  
Re: 92 Z28 5.7 won't start, help needed
Ok, so I replaced the injectors. Still no luck, the car doesn’t start. I’m down to two things:

Either the coil is sending weak spark or its going to have to be the ECM.

This car is really making me work. 😡😡
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Feb 23, 2020 | 06:16 PM
  #9  
Re: 92 Z28 5.7 won't start, help needed
If it will kick off on starting fluid, I would think it would run on good gas. Check and clean all the grounds on the engine, I think there's 2 or 3 of them on heads and maybe the water neck. Then see if you can get a noid light to see if you have an injector pulse. Also pull a couple plugs out and make sure you don't have them soaked with fuel now.
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Feb 23, 2020 | 09:48 PM
  #10  
Re: 92 Z28 5.7 won't start, help needed
Quote: If it will kick off on starting fluid, I would think it would run on good gas. Check and clean all the grounds on the engine, I think there's 2 or 3 of them on heads and maybe the water neck. Then see if you can get a noid light to see if you have an injector pulse. Also pull a couple plugs out and make sure you don't have them soaked with fuel now.
Good idea, thanks. Today, I replaced the coil and still nothing. Only thing left is the ECM and check those things you mentioned. I did check for 12V at the injectors (only cylinder 1, it checked out fine). I need to try the noid light, thanks for the tip.
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Feb 25, 2020 | 11:24 AM
  #11  
Re: 92 Z28 5.7 won't start, help needed
Quote: Good idea, thanks. Today, I replaced the coil and still nothing. Only thing left is the ECM and check those things you mentioned. I did check for 12V at the injectors (only cylinder 1, it checked out fine). I need to try the noid light, thanks for the tip.
I also noticed a sensor plug disconnected on the passenger side. I looked it up and saw it was the knock sensor. I read it has to do with timing and sending knock signals to the ECM. The top of the sensor is cracked so I ordered a new one. Could this be the reason why the car is not starting??
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Feb 29, 2020 | 02:25 PM
  #12  
Re: 92 Z28 5.7 won't start, help needed
Quote: If it will kick off on starting fluid, I would think it would run on good gas. Check and clean all the grounds on the engine, I think there's 2 or 3 of them on heads and maybe the water neck. Then see if you can get a noid light to see if you have an injector pulse. Also pull a couple plugs out and make sure you don't have them soaked with fuel now.
You're a genius, the ground ground on the back of the head were lose. What a pain to get in there and tighten them up. The car started right up. Thanks for your help.
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Feb 29, 2020 | 10:03 PM
  #13  
Re: 92 Z28 5.7 won't start, help needed
Quote: You're a genius, the ground ground on the back of the head were lose. What a pain to get in there and tighten them up. The car started right up. Thanks for your help.
You're welcome. Glad it was something simple. Thanks for the update.
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