1990 Nissan Truck Won't start

We should probably start by checking fuel supply/pressure. Which 2 cylinders is it that appears flooded? Once you've made sure you have plenty of fuel, then we'll check for 'spark'.

Does that one have 8 spark plugs or just 4? Some had a 'leading' and a 'trailing' spark plug in each cylinder. If the plugs are getting fouled, that probably means they either aren't firing or they're firing at the wrong time. But, it probably means that the cylinder is getting fuel. Is there any way the plug wires to those two cylinders got switched by any chance? Double check your firing order and make sure they are on the correct cylinders. You may need to check the compression on those two cylinders. The timing belt may have broken. Can you take the oil fill cap off and see the rocker arms? If so, have someone spin the motor over while you watch the rockers. Are they moving? If not, the timing belt isn't in tact.

OK, I've just seen it too many times, sometimes people start poking and prodding and end up switching the plug wires around and not remembering how they are supposed to be. But if that's not the case, we'll proceed. When it stops raining, check the rockers while someone spins it over. See if any of the valve train is actually turning while the motor is spinning. If not, we'll put a timing belt on it. Just get back with me. I'm here just about all the time.