Crank but no start

Tiny
RFBMONEY
  • MEMBER
  • 2010 HYUNDAI ACCENT
  • 1.6L
  • 4 CYL
  • 2WD
  • MANUAL
  • 180,000 MILES
The vehicle listed above (Blue) is a hatchback.

About a year ago I was driving and car shut down suddenly and would not start. I tested for a bunch of potential causes and it ended up being my ECM (engine computer) shorted out/went bad (I actually opened it up and saw burnt spot on circuit board). I changed my ECM back then (with a used ECM with matching numbers) and this fixed my previous no start issue. However after changing the ECM out code check engine light no longer came on and obd code readers no longer communicated with car. Car started and ran well for about a year like this though. No back to present. Car shut off again while driving and no start now.

Back to present. Driving on interstate and engine suddenly stopped running. Unable to ever restart and now just crank no start.

Thinking may be ECM again and bought another recycled ECM (again matching numbers) but this time did not resolve issue (I actually bought 3 different matching number used ECMs and none of them have resolved issue).

Now thinking maybe not ECM (but again current set up not throwing codes) and tried to start testing/changing out other items by process of elimination (trying to verify fuel, spark, air, and compression)

-Verified battery is good.

-Tested all fuses and relays and tested good.

-Unscrewed shield and verified timing belt appears to be in place and not damaged.

-Tachometer jumps up some at crank (I'm told this indicates compression).

-Changed spark plugs and verified spark at each of the four coils when cranking.

-Changed Crankshaft position sensor and changed cam shaft position sensor.

-Changed fuel pump assembly and verified pump turning on at car start attempt/crank.

-Sprayed starting fluid into intake manifold and attempted to start and again crank no start.

Also I believe fuel is reaching combustion chamber as I pulled out the recently changed spark plug and it smelled of fuel.

I am not sure what else to try. Based on what I have done it appears I am getting spark, fuel, and I think compression. If its not my ECM is there some other sensor or factor that can throw off timing/fuel, air, spark mixture? I guess it could be some kind of vacuum leak (hidden hose failure or something) but would I get an RPM jump at crank if that were the case?

Any thought or diagnoses would be appreciated.
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Friday, February 26th, 2021 AT 11:34 AM

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Tiny
KASEKENNY1
  • EXPERT
Here is a guide that will get us started but you are on the right path:

https://youtu.be/dCjmRL3p4Cs

However, we need to find out for sure if you have compression. The tachometer jumping does not indicate compression. That indicates the crank sensor is picking up the revolutions of the engine but not compression.

https://www.2carpros.com/articles/how-to-test-engine-compression

Then we are going to have to find out if the fuel pressure is correct as you may have fuel but not enough pressure to get the engine to start.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Then we need to check for ignition by removing a spark plug and holding it against the block and crank the engine. This will show if we have spark at the plug.

Basically you need fuel, spark, compression and air to get the engine to start. So we just need to cross each of these off one at a time.

Let me know what questions you have. Thanks
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Friday, February 26th, 2021 AT 5:40 PM

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