Hey team I’m having an issue with my 94 L200 4D56T. Took it up into the high country and ran fine doing clean water river crossings, some getting quite deep, and it ran like a dream.

As soon as I hit some mud it spat the dummy. It would idle ok, but would eventually die while idling, and as soon as I put the gas on it’d choke and splutter and die and blow black smoke. This would happen after 1000rpm and it would die before 2000rpm.

My unsuccessful bush mechanics involved:
Pumping, draining, and refilling the fuel filter
Checking the diesel feed to the injectors (all flowing at an idle)
Disconnecting the fuel tank breather filter
Bypassing the fuel filter altogether
Bypassing the air filter

Nothing seemed to work or make a difference. The longer it sat off, the longer it would then idle after turning it back on. I’ve let it sit overnight and currently driving a 200km drive in the rain without any issues whatsoever

Any ideas?

Well black smoke is lack of air to fuel. What’s the air side like up to the inlet manifold??

It has a snorkel fitted through a podfilter going to the turbo then through a front mount intercooler to the intake manifold. I tried disconnecting the airfilter but it did not make a difference, but didn't think to disconnect the pipes feeding the intake manifold directly to test for a block in the front mount intercooler.

It's frustrating because now it is running fine so I can't diagnose and fix the problem!