I have an 88 f250 7.5 with the 5 speed 4wd.
it Has 88k miles and is not a daily driver but is a fun/toy truck with 6 inch lift and 37s has had the emissions deleted and medium cam for several years no problems until now. Always ran rich and got about 7-9 miles per gallon and will burn your eyes out if you stand near the exhaust
cat converter has been deleted
it only has the front tank and the selector thing deleted. and has a on the frame pusher fuel pump

so i pulled spark plugs to see what ones didn't work and it's not running on 1 4 6 7 or maybe 2 3 5 8
literally every other cylinder on the dist. Cylinder not running but seems to be receiving spark and fuel and the lifters are working
i will double check when I get home
it runs rough and obviously no power
same through the whole rpm range but will run and start no problem

Things replaced at my own discretion before problem arose and many miles put on before the problem arose.
New fuel pressure reg with permanent pressure gauge pressure at 35-40 at idle
new distributor
new coil
new map sensor
New o2 sensor
New IAT sensor intake temp sensor
New CTS coolant temp sensor
New remote mounted ignition control module

Since the problem arose i have tried the following
Unplugged injectors and or plug wires to find dead cylinders all injectors rebuilt. Cleaned. Tested with a external battery that they flow and stop flowing. And blew them out backwardsthey all have 12+ volts key on. ground test light to see that the computer is telling the injectors to fire via the ground signal
new cap and rotor and ford oem plug wires and motorcraft spark plugs gapped to .045
replaced fuel filter

the cylinders that dont run i can pull the spark plug wire off and hold it close to the cap and i can see a blue spark jump the gap between the Unplugged wire and the cap

 

Any chance you could get some KOEO codes?

 

I'm not a 7.5 specialist like some, but if it was mine...

Run codes, either manually with a jumper wire & counting MIL light flashes or the sweep of a meter if burned out. Or pick up a Inova 3145 for about $30.

I'd plug the 2 vacuum AIR solenoids all back in just to keep them from setting codes, there is no help for a removed EGR codes. If no codes (it's never going to give a pass), open up the ECU & check for leaking capacitors

Verify KOEO your remaining pump primes/runs 1-2 seconds, shuts off & sound normal.

Rent a EFI rated pressure gauge & verify rail pressure of 35# idle, #40 with the vac line removed from regulator & no fuel in regulator vac line.

Id pull the the ECU connector & test continuity/resistance on the white and tan wires and all injector connectors.

What the heck do the plugs look like?

 

Fuel press holds at 35 at idle and drops to 30 and raises back to 35 when applying throttle, and over 40 with vacuum line disconnected

The dry plug was a cylinder that runs and the wet one was on a non running cylinder. Dont mind the white **** i had to get them out of the trash

Found this green wire connected into the test port ? No idea but runs the same plugged in or unplugged


So the fuel pump primes when the key is turned on. The codes will not flash I suppose someone must have removed the bulb when they did the emissions delete.. I will take it to my friend with a scanner
it runs barely enough to drive.. i checked the injector power and ground with the test light hooked to both sides of injector wire. So i would have to have both ground and power at the injector for it to work. If that makes sense. I grounded my test light on the tan / white wires and tested red wire and it was flashing with the speed of the motor rpms

 

I did not test the ecu itself
if anyone has a spare in the central mass. Area let me know. Im not sure what im looking at inside of it so i dont dare take it apart.
it has a brand new adjustable fuel pressure regulator

As far as the emissions pumps and plugging them back in, i cant it was done by the previous owner over 10 years ago

 

Bueller? 😔 could the distributor cause the spark to be mis timed on 4 plugs ? Could the ignition control module or the ecm ? Very odd I have fuel. Spark and the rockers are moving for 4 cylinders to not run. Not on the same bank and one side is the middle two cylinders and the other side is the outermost cylinders
I ordered a scan tool my friend didn't realize his scanner did not have an obd1 adapter

 

Very interesting problem and I'm here to help you solve it if you want. Because cylinder numbering is confusing (ford does it different than everyone else and you gave 2 different cylinder drop reports) can you draw on a piece of paper the top view of the engine and show which cylinders aren't working?
I think your ECU is fine. The injector drivers in the ECU seem to be firing the live cylinders ok.
I'd guessing your ignition system is dropping everyother spark for some reason. Very odd and interesting.
Do you have a timing light you can clip on each sparkplug lead and confirm each lead causes the timing light to flash consistantly?

 

You have spark on all eight cylinders but only fuel on four (two on each bank)? Not unusual at all. That’s how the bank fired fuel injection works on the speed density system. The computer commands four injectors to fire and then the other four. Is it possible you have damaged wires from rodents?

 

But, according to the OP, the dead cylinders don't correspond to just one injector circuit. And the OP said he checked the injectors and they were all getting power and signal from the computer. So we can rule out fuel system and focus on ignition system.

 

You have the plug wires routed like this?

 

Here's your injector wiring. Just so you have it.

 

Any update on this?

 

I was not feeling up to working on my truck the last week or so I got outside today and I 1st checked that all of my spark plugs are firing with a timing light hooked to individual spark plug wires and they are all working
I checked the routing of all of my spark plug wires to the correct cylinders and correct firing order
And then I double checked which cylinders had no difference when unplugging the spark plug wires
cylinders 5,8,3,2 no difference when Unplugged or plugged in
I then warmed up the truck to operating temp, all koeo codes 31 82 85 84 10
All koer codes 30
also recently I bought a timing set only to realize I had almost no play when turning the crank back and forth in small increments and watching the dizzy spin to look for sloppiness. None was found so i did not do a timing set. And the distributor is also pretty new but have been driving on it a while since I replaced it. The adjustment bolt is tight

 

Been really missing driving the old girl

 

Here's an off-the-wall thought......

Since each throttle blade effects the same cylinders in question (every other cylinder - two inner and two outer on each bank), is it possible there is something blocking one "barrel"? The passages are completely separate all the way to the intake manifold save for two very small holes and the IAC passage. Throttle shaft broken maybe? Just spitballing. Something blocking one of the tubes from the filter?