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Bronco1979
New User
Jan 3, 2015, 3:44 PM
Post #1 of 2
(1039 views)
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engine will not run
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1995 geo prizm engine just quick running when being driven. Has spark and fuel. Checked timing belt all still lined. Am I correct in thinking the ECM is bad?
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Hammer Time
Ultimate Carjunky
/ Moderator
Jan 3, 2015, 3:57 PM
Post #2 of 2
(1034 views)
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Re: engine will not run
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No, there is no reason to jump to that conclusion.
Complete the rest of the testing.
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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