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1994 Chevy truck wont start
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tyler
New User
Oct 1, 2009, 3:05 PM
Post #1 of 2
(4806 views)
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1994 Chevy truck wont start
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1994 Chevy truck 4.3 v6 will not start. Starting about two weeks ago, the truck started to miss when idling. It would idle then bog down, up and down,if you gave it gas it would clear up. Changed Fuel filter,then throttle position sensor. Didnt change. Added seafoam and Heet.Next Day drove perfect for One day. Then started again. This time clean butterflies on carb. Still idiling up and down.  Changed rotor and Cap. No change!! Let sit in yard for two days, before working on it again. This time it cranked up and ran good for three days,no problems. Now it is sitting on the side of the road and will not start ,will not even try to hit . Changed coil,module in distributor, spark plugs. I am getting fuel and fire but it will not even try to crank. The only reason I changed coil,mod, and spark plugs,because someone told me it didnt look like it was firing hot enough. Move distributor around ,back n forth, to see if it would try to at least hit on one cylinder. Nothing. Help
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Hammer Time
Ultimate Carjunky
/ Moderator
Oct 1, 2009, 3:36 PM
Post #2 of 2
(4800 views)
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Re: 1994 Chevy truck 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.
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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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