Put diesel in a gas truck

AGGGHHH! Bail out!

Okay, actually, ... How much did you put in? Diesel is harder to ignite so you can expect misfires, it burns much hotter than gasoline which could melt aluminum pistons, but it also has lubricating properties that are not found in gas. Diesel fuel can be used to free rusted pistons and rings in engines that have seized up from being in storage a long time but that's a different issue. The point is it's unlikely anything will get damaged, but you'll want to get as much of it out as possible. If you just put in a few gallons, and it still runs, dilute it with lots of gas and run the whole tank out. If you filled it with diesel, I would pump it out but I can't think of what to pump it into.

Diesel fuel is sprayed in under around 2000 pounds of pressure because it's going right into the cylinder instead of the intake manifold, but it also needs high pressure to vaporize properly. Gas systems only run a maximum of around 55 psi. I don't know how that will affect the diesel but there is going to have to be enough gas entering also to form a combustible mixture.

Being the cheapskate I am, I would try to run the truck's fuel pump and use the fuel pressure test port to pump the fuel into gas cans, then try to use it in one of my pieces of construction equipment. By using half a gallon of your concoction along with ten gallons of fresh diesel fuel, I doubt there would be a noticeable problem.

That's dandy news. If the tank is almost empty, I would try filling it only 1/4 way first. That way you will run the diesel out faster. If it sputters or hesitates but it does run, then I would fill up all the way to really dilute that diesel and it will probably be fine. So you get a fuzz extra lubrication through the injectors.

Remember too that engine oil that gets past the piston rings burns in the engine and goes out the tail pipe without causing any other damage. Diesel fuel is better than engine oil in the combustion chamber.

How much gas is mixed with that diesel?

Got it. The engine is trying to run on a concentration of diesel that is much too high. Go back to my original story of filling the tank half way. That should give you enough percentage of gas so the engine will run. Keep in mind that right now the fuel rail and supply line is full of too much diesel fuel. The pressure regulator is on the engine and there is a return line going back to the tank. When you're cranking the engine, the pump will be circulating the new fuel through the supply and return lines. That won't take very long but it could be a minute or so. Once there is a higher concentration of gas in the lines, it will still be necessary for the diesel to work its way through each injector. I'm 99 percent sure the diesel will puddle in the intake manifold and will not foul the spark plugs. Once the engine starts, the diesel will burn and go out the exhaust system as a gas, not a liquid, so it shouldn't affect the catalytic converter.

If you find that the engine runs, maybe poorly, but acceptably, run as much of the diesel out as you can stand, then fill the tank to dilute the diesel as much as possible. I think you're going to find this will be over pretty soon.

You can look at it this way too. I just filled my old rusty trusty Grand Caravan with gas last week. Today the price is almost 15 cents per gallon lower! I'm thinking about dumping that expensive gas in the ditch so I have room to go buy a tank of cheaper gas! (Makes sense to me)! You only have to dump three or four gallons.

Caradiodoc is on track there, fouled plugs won't help at all
If there is oil on them, it will need to be removed or the voltage can't build up and spark doesn't occur, like my 2 stroke dirt bike!