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1994gm truck start problem
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jamesg1551
User
Nov 27, 2017, 2:55 PM
Post #1 of 3
(1617 views)
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1994gm truck start problem
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1994 gm 1500 truck elec. problem. will not start. checked most common things to check. manual said. white wire coming from ecm should have 12 volts to supply modual in distubator , and this wire goes to the ecm unit only and I have no voltage. but wire shows around 200 ohms. is that normal to drop the voltage . have traced wire from dist to ecm no breaks. if I cut wire tape up going to ecm and put 12 volts to pcm unit ( on dist. modual ) would truck start and run or burn up dist. modal ? wire coming from coil and ignition switch has 12 volts. please help, this is getting old. thanks. james
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Hammer Time
Ultimate Carjunky
/ Moderator
Nov 27, 2017, 3:18 PM
Post #2 of 3
(1609 views)
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Re: 1994gm truck start problem
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Before doing anything, make sure the check engine light is coming on for bulb check when the key is first turned on without starting it.
after that
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.
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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