I have a '91 5.0 EFI w/ E4OD 4X4. No spark, well it keeps coming and going. Very strange, seems when it quits, I can put my spark tester between the coil and distributor inline of plug wire and it will start firing and crank. Sometimes runs a long time (driveable) and sometimes not even 1-2 minutes. My question is from where I'm checking spark, would this be coil problem or distributor module? Where does spark begin and what flow route does it take? AND, while no spk condition, fuel pump never shuts off.seems it never primes or something, cause when it's going to crank, pump comes on for about 10 secs and shuts off,but when it doesn't shut off, I can look for it not to crank.But it always has fuel pressure and no spark during this condition.Could this be tied together???
Also have another trouble, not sure if this ties in,butI don't think so. It's more of a tranny problem. When put into drive or reverse, takes up to 1 minute for tranny to engage (always). Also, speedo needle jumps around while driving. Otherwise shifts fine, no slipping.
Thanks for any help!

 

Not going to touch the tranny issue, doesn't sound good.

As I understand the system, the EEC IV module (side of distributor) sends a voltage to the primary side of the coil, the field in the coil builds up and induces voltage into the coils secondary (high tension, spark plug side) when the module stops the flow of power to the coil. The pick up (hall effect sensor) located inside the distributor is what triggers the turn on and off of power in the module. Boy, that's clear as mud.

Another attempt, look at the old battery ignition. 12 volts to the (+) terminal(primary) side of the coil, out the (-) terminal to the points (inside distributor). Current flows and a field is built up in the coils primary windings as long as the points are closed. Once the points open, the primary field colapses quickly and induces a spark in the secondary which zaps the spark plugs. There, thats easier to understand, now use the solid state stuff to replace the simple points and condensor. And that, is how I define progress.

 

So, am I checking too far down line to tell which part is at fault??? How would one determine which is falty componant?

When you say tranny doesn't sound good, what would be worst case? Would a general rebuid kit cover all or is there some gray areas in there as well?

 

Using a 12 volt test light, see if there is a constant light at the (+) terminal of the coil, and see if the light blinks at the (-) terminal. If these two conditions are met but the engine won't run, the coil secondary is bad. No blinking light the problem is either the module or the pickup (hall effect) sensor. For you, its time to exchange whole distributor. Replacements are almost cheaper to buy than the components.

You need to talk to a tranny man about your issues there. Open a book and look at the details of the valve body. It has springs, steel *****, ports and passages for every shift point including forward and reverse gears. Its not voodoo, but its not as easy as a "rebuild kit". The whole transmission works on oil flow, perhaps the filter is plugged up, and it can't get any oil.

 

i heard somewhere that the moving speedo is caused by alot of stuff, heres a link to a site where the guy had the same problem. the transmission thing sounds like a bad solenoid.

http://www.ford-trucks.com/forums/35...e-baffled.html

 

My brothers 91 did this same thing with the spark. Check the wires to your EEC Relay, one of his was corroded and sometimes wouldn't make contact.

 

Sounds like it could be the tfi module. They work sporadically when they begin failing. They fail due to heat usually. Does it start more often when its cold and die after the truck warms up?