Well I took the FPDM off and didn't see any corrosion any where. Any more suggestions? I don't have the money to take it to a mechanic.

 

Now, to keep it from corroding, clean the backside off thoroughly and coat it with something - then reinstall it using some standoffs so it doesn't contact the axle.

 

Will it be ok to put some rubber strips between the FPDM and axle? Also, I didn't take the black cover off, was I suppose to?

 

Think you Replace it with the one that fits the Expedition. You have to be able to test the changing voltage to the pump for speed changes/; or pump psi changes otherwise. It would make sense if you find no reason for current problems/corroded connection it be in the fuel pump module or the pump. It would be easiest to switch the fuel pump module with a known good one if you had one. Also the fuel pump relay could be shorting in th coil, test its voltage drop. Try switching R303 fuel pump relay with another relay, see if the blown fuse moves.

Fuse #33 powers 154R75E transmission, Heated Oxygen Sensor (HO2S) #12, Heated Oxygen Sensor (HO2S) #22, Coil On Plug (COP), Ignition transformer capacitor 1, Ignition transformer capacitor 2, Ignition coil (4.2L), Ignition transformer capacitor Check to see if you have a rubbed thru wire around top of motor maybe near ignition capacitor lead. Or a burned wire down by O2 sensor.

 

I will definitely try that stuff out. I unplugged the 16 pin wiring harness that is taped to the wiring harness going to the pcm, turned the key, and the fuse didn't blow this time. Does that 16 pin wiring harness control the coils or what? If so, what should I do next?

 

I'm gonna check the manual, be right back. Fuses 32 and 33 are in there kinda together. with the sensors of the motor and transmission. 33 is for the ign, and the o2's + trany sensors with transfer case. It feeds also into engine sensor circuit at PCM. There 32 does the heated PCV and other engine sensors along with some O2 sensor power. Unplugging until you find it or tracing the short with a ohm meter. With 12 volt power going to the cop's when you turn on the key it then goes to the PCM for the path to ground firing the spark with the help of the transformer capacitors. Here is where you are looking for a shortcut to ground before getting back to the PCM. Otherwise the path to ground will be a shorted PCM. You should have a code for a PCM problem, if it were bad.

 

But my friend hooked up a diagnostic machine and we didn't get a code. At that point, we started to look at the fuse box and found that fuse 33 was blown.

 

The 16 pin rectangular connector that is taped onto the harness below the PCM connectors. This Connector will stop the power from going to the ignition coils and eliminate part of the circuit. If it doesn't blow then you know it is in those coil circuits, so the next step is plug that connector back in, and unplug all 8 ignition coils, retest, if it doesn't blow plug them in one at a time until it blows again and that will isolate the circuit with the problem.
Look at that individual plug, for obvious damage/heat/burning.
Look for chaffed/crimped/wire pinched between 2 metal pieces or touching a hot place. The wiring to that coil because the wire was close to, and rubbing on the metal power steering reservoir bracket. Check very closely and sure enough that the wire had been rubbed just enough to cause a short. I couldn't even see any copper. I mean this was very small. Anyway the short took out the coil

If that doesn't get it:

If your short is before the return ground gets to the PCU the fuse blows and the Pcu just thinks the key is turned off on that circuit. It will probably take you and a friend to disconnect all and reconnect one at a time to find it. It may be damaged in the wire harness and hard to find, except thru inspection and vom/continuity while disconnected.

I put 2 wire diagrams in my pictures. Fuses 33 & 32. The 2 pages show their circuits. The top circuits are 33 and pay attention to the violet/white wire when going to the second page. The reason I mention the second fuse is due to them kind a being connected at the hip. If the ground/short is in the PCM you would have a code to go buy. The downstream O2's are on the Fuse 33 circuit. Make sure one isn't burnt wire. If O2 was open it would code. You can enlarge the pictures and print them.

 

I give up!! I decided to unplug the coils on the driver side of my truck by plugging them in one at a time, trying to see which one is causing the fuse to blow. None of the driver side coils caused the fuse to blow. I checked each wire to see if they were burnt, rubbing, or any damage at all to those wires but everything seemed fine. After I checked all the coils on the driver side, I decided to see if the truck would crank. Wouldn't you know it, it fired right up. Usually I wouldn't get mad when my truck cranks but this time it pissed me off because now I won't find the problem until it starts blowing fuses again. The wires going to the coils, from the driver side, is the only wires that I moved around so logic tells me that there is a short in one of those wires. Either that or maybe one of the coils wasn't plugged in all the way. Who knows!! Maybe God answered my prayers!! Is there anything else I can check?

 

Fill a glass of tea and sit back and relax! whew! Breath deep and slowly let it out. Again, Again. Now you're almost there. Do you have a Cat ?