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breckert
User
Oct 30, 2009, 9:17 PM
Post #1 of 2
(1677 views)
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hey everyone i have a 96 bravada with a 4.3 vortec
and all of the sudden it wont start. i was driving, then i stoped and got out and about 5 min later i went to get back in and when i tried to start it it wouldnt even turn over. it has done this before but after a little bit it seemed to start, but this time it wont. does anyone no what this could be. i really need to get this fixed because i need my car for college so any help would be much appreciated.
thank you
brian
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 31, 2009, 4:05 AM
Post #2 of 2
(1669 views)
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Re: car wont start
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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 test 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.
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 other tests are passed. then perform a complete compression test and record the results. All cylinders should be over 120lbs in most cases and all be within 10% of each other.
Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
All that being said, I can tell you the #1 cause of "no starts" in this vehicle is usually a bad fuel pump. The fuel pressure is critical on this engine and it won't run under 55PSI
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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.
(This post was edited by Hammer Time on Oct 31, 2009, 4:06 AM)
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