Discussion:
Crank no spark

I have a Doosan G18S-5 that I am pulling my hair out over. It has the Hyundai LP engine with Woodward fuel system. It's is not a dual fuel truck, strictly LP. Engine cranks but won't fire. I have replaced the crank and cam sensors. Wires from both sensors ohm'd out good. I back probed a test LED on both sensors and got a pulsating light while cranking. Spark plugs are not emitting a spark and when I put my test light on the coil pack wires, the light did not pulsate. The coil packs have two wires instead of three. At this point I am thinking it's an SECM issue. Before I replace SECM, is there anything else, besides crank and cam sensors, the SECM needs to get a signal from before it sends a spark? Also, no fault codes are showing on the dash. I don't have Doosan software to plug into the truck. Thank you
  • Posted 13 Feb 2026 12:48
  • By Tomcatt78
  • joined 4 Mar'21 - 6 messages
  • Pennsylvania, United States
Showing items 1 - 9 of 9 results.
I believe that is a Theta engine
I may have info for you
I will look and if I have anything I will get it to you.they used this engine in Clark lifts as well
  • Posted 20 Feb 2026 00:51
  • Modified 20 Feb 2026 00:53 by poster
  • By John_Bradley
  • joined 10 Aug'22 - 285 messages
  • Texas, United States
Jb69
I checked oil pressure sensor resistance and cleaned up some of the rust since it gets a ground through the oil filter housing. I also tried bypassing it by pushing the diaphragm up with a pick tool while cranking the engine. That didn't help. I'm not real familiar with Doosan so I'm not sure if they have any other safety sensor other than the usual ones. My background is with Unicarrier, CAT, and Mitsubishi.
  • Posted 19 Feb 2026 13:27
  • By Tomcatt78
  • joined 4 Mar'21 - 6 messages
  • Pennsylvania, United States
Also is there a bonnet switch? Some trucks kill the engine when the bonnet is up.
  • Posted 19 Feb 2026 09:16
  • By andrew_k
  • joined 17 Mar'07 - 353 messages
  • England, United Kingdom
Is there a live to the coils? I assume the ecu switches the earth.

Also are there any safety's that would kill spark if it lost oil pressure or got too hot? Are the sensors faulty?
  • Posted 19 Feb 2026 09:12
  • By andrew_k
  • joined 17 Mar'07 - 353 messages
  • England, United Kingdom
I replaced the SECM and spark plugs but neither resolved the issue. There are 4 small square blocks next the SECM which I'm assuming send power to the coils. The schematic refers to them as PWR TR 1, 2, 3, and 4.
  • Posted 19 Feb 2026 08:05
  • By Tomcatt78
  • joined 4 Mar'21 - 6 messages
  • Pennsylvania, United States
It has a Hyundai 2.4L engine with a Woodward fuel system. Unfortunately The information on the engine tag has been wiped off. I have some Doosan schematics. The ones I have are close but have some differences such as the coil packs have 2 wires and the schematics I have show 3 wires.
  • Posted 19 Feb 2026 08:04
  • By Tomcatt78
  • joined 4 Mar'21 - 6 messages
  • Pennsylvania, United States
I haven't checked the timing belt but did check that the cam is moving while cranking.
  • Posted 14 Feb 2026 10:29
  • By Tomcatt78
  • joined 4 Mar'21 - 6 messages
  • Pennsylvania, United States
First have you checked timing belt ?
  • Posted 14 Feb 2026 09:05
  • By John_Bradley
  • joined 10 Aug'22 - 285 messages
  • Texas, United States
Jb69
Do you know what system it is?

Do you have any information on it at all?

I have some woodward service information I can send you.

Andy
  • Posted 14 Feb 2026 07:03
  • By andrew_k
  • joined 17 Mar'07 - 353 messages
  • England, United Kingdom

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