Engine cranks but will not start

Tiny
ANGELD1993
  • MEMBER
  • 2000 MERCEDES BENZ ML320
  • 3.2L
  • V6
  • 4WD
  • AUTOMATIC
  • 156,000 MILES
I have the vehicle listed above that will not start. I've replaced battery, alternator, starter, spark plugs and wires, EGR valve, crankshaft position sensor, fuel pump and filter system, evap, axillary coolant pump. Plus I replaced all relays and fuses. It still doesn't start. It's trying to crank but will not start. Does anyone know what else it could be?
Thursday, March 11th, 2021 AT 9:57 AM

3 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
There is not much left on the list but we need to find out what we don't have in order to get it to start. You need spark, fuel, air, and compression. Here is a guide that will help with this:

https://youtu.be/dCjmRL3p4Cs

We can assume at that point that we have air and compression as spark and fuel are more common to be the issue.

So let's use starter fluid in the intake to see if it fires. If not, pull a plug and hold it against the block and crank the engine to see if you have spark.

Then we need to find out if the theft system is activated. If it is, that will cut fuel and spark so the engine does not start.

Let's start with this and go from there. Thanks
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Friday, March 12th, 2021 AT 9:41 AM
Tiny
ANGELD1993
  • MEMBER
  • 3 POSTS
I put the spark plug tester on my car and barely light up. Could it be the ignition coils?
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Monday, March 22nd, 2021 AT 5:08 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Absolutely it can. If you have weak spark then it sounds like the secondary side of the coil is not causing the high voltage spike to generate the needed voltage. I would replace it and retest. Good work.
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Monday, March 22nd, 2021 AT 6:34 PM

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