Crank no start intake backfire

Tiny
DMANIA29
  • MEMBER
  • 2000 DODGE RAM
  • 3.9L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 189,000 MILES
Tune up was completed crankshaft position sensor changed camshaft position sensor changed and engine will turn, but wont start. Upon turning key and tapping gas intake hose was blown off and white smoke appeared on the right side of engine somewhere. I am stumped.
Wednesday, October 26th, 2016 AT 2:55 AM

3 Replies

Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
Why were those sensors changed?
How did it run before these repairs?
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Wednesday, October 26th, 2016 AT 3:44 AM
Tiny
DMANIA29
  • MEMBER
  • 2 POSTS
Truck was not running got misfire codes did tune and still wouldn't crank so I changed those sensors thinking it would start
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Friday, October 28th, 2016 AT 3:46 PM
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
So, there was no justification at all to change those parts.

Here is how you find your problem.

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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Friday, October 28th, 2016 AT 3:49 PM

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