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97 Chevy 5.0 Replaced everything still no start
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JP97
New User
Nov 6, 2013, 7:50 PM
Post #1 of 2
(1574 views)
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97 Chevy 5.0 Replaced everything still no start
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I have a 1997 Chevy Silverado with a 5.0L. I was driving home and engine quit and would not restart. I recently replaced Cap, Rotor, Wires, Plugs (Gapped them according to manufacturer specs). Then I continued to get a misfire code. Mechanic said it was probably the injectors draining off over night. Since the breakdown I have replaced fuel pump and strainer, Fuel filter, Crankshaft sensor and ignition module. Tried a new coil as well. Today I jumped the fuel pump at the relay and got fuel pressure. When I check the female relay pins I don't show the constant power I thought I should at pin 87 with key on. Testing was done with a test light. But when I jump pin 87 to 30 it seems I get pressure in the rail again. I don't have a fuel pressure gauge to test, but when I relieve all of the pressure and then I do the jump between the pins pressure comes back. Now I am confused. Do I not have the power I need? Is the PCM bad? Is the relay bad?
Please help!! I need my truck for work and kids!
(This post was edited by JP97 on Nov 6, 2013, 7:51 PM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 6, 2013, 8:00 PM
Post #2 of 2
(1565 views)
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Re: 97 Chevy 5.0 Replaced everything still no start
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You're not supposed to have constant power there. You have to test the fuel pressure with the relay in place.
Here is everything you need to test.
All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.
Every engine requires spark, fuel and compression to run. That's what we have to look for.
These are the basics that need to be tested and will give us the info required to isolate a cause.
1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.
2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on. Since your injectors aren't exposed you will have to access the wiring going to them.
3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.
4) If all of these things check good, then you would need to do a complete compression test.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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