Do you have the exact CEL trouble codes available?
If its an ECM trouble code why are ohm'ing out the injectors?
Can you furnish the exact fuse thats blowing and what devices it supplies power to?

Blowing a fuse only when on a bumpy gravel road and only when the engine is hot should be a big clue to those techs.
Are they doing all their testing when the engine is hot?

It could be a harness or wire shorting out to the frame from the bouncing
or
some device that when hot short circuits which is not all that unusual.

 

The fuse that is blowing is M25 Fuel Pump. It supplies power to the fuel pump as well as the injectors.
They have tested when it is both hot and cold.
No I don't have the exact code written down but I know that is says the issue is either ECM or ECM Relay.
We do believe it is a wire somewhere shorting out. However we can't get it to give a code for that, only the ECM. When checking the wires for a gap/short they all check out.
They are of the opinion that an injector may be getting hot and causing a short or a coil pack but because they aren't throwing codes so they are hesitant to move in any one direction. Probably because they put a ECM in it when that wasn't the issue.
Im looking for ideas of what to test next because they are all out of ideas and I need my vehicle back so I can work.

 

Have they ruled out a bad fuel pump assembly?
The fuel pump assembly has an electric motor and bunch of wires going into/out of via the connector and also some wiring on the pump itself.
Its an electrical mechanical device which i'd think which would be one of the prime suspects for a short circuit situation.

Here's a 2015 Wrangler fuel pump.

Depending on how many time the fuse blew, i'd think if it was an injector itself it would sooner or later go bad permanently.
If its injector related my bet would be a short somewhere in the injector harness.

A coil pack on the other hand generates high spark plug voltage so could be a short circuit candidate when it gets hot.

Intermittent and/or heat related problems can be a beech to trouble shoot.
In my experience before pulling out the parts cannon and the heavy artillery trouble shooting tools i'd first find out what the fuse supplies power to which apparently they did.

Then i'd use a heat gun on each component the fuse supplies power being careful not to over heat all the while tapping it lightly.
Of course heating the fuel pump is out of the question for a bunch of reasons.

If that don't work jiggle, bounce, pull, push all involved harness cables.

Maybe the techs did some or all of that already.