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.
Sunday, December 18th, 2011 AT 8:37 PM