No firing on 98 Navigator

check an owner manual or repair manual for location. I've seen fuel filters under the car in the fuel line and also could be attached near the pump. One car I had the filter was housed in a cheapo piece of plastic attached to the fire wall.

Check and see if fuel pump is working and also check your fuel filter as it could be plugged.
Check and see if the spark plugs are firing. Pull a spark plug and see if they need replacing . Could be an electrical problem as far as the engine firing. Could be a number of things.

try taking gas out n changing it. ethenal is good for that. if you dont drive it everyday water will settle at bottom of tank. of the sock on bottom of fuel pump is stopped up

have to check if have fire on spark plugs.if no check timig belt, or inigtion coil

There rite on top the engine under the fuel assemble there black with a plug goin to it with two wires . It's the one srew that holds them dont disconnect fuel lines use swivel on a 3/8 wrench you need to find which ones are not firing trust me I had two of em to day

take of the fuel filter and blow it out. i had the same problem with a 2008 ford f150 5.4 v8.

BUY A SPARK TESTER AND FUEL PRESSURE GAUGE TESTER.TO CHECK FOR FUELPRESSURE AND USE SPARK TESTER TO SEE SPARK PLUGS GETTING FIRE.

the oil pressure sending unit is usally located in the same side the oil filter is and this is because the oil filter is connected to the oil pump so there should be one little single wire in that area

mass air flow sensor is not the problem, I had the exact same problem and have done much research on this. Check the PVC rubber hoses, especially the elbows for cracks. You probably noticed your gas mileage has been horrible too. Hope this helps

if it were the cranksensor it would not start at all.you would have no fire.