My dad has an 1990 5.8L (351ci) fuel injected Bronco. He called me yesterday because he ran out of gas and needed some more brought over to him. My dad has regular problems with his autos because he doesn't do regular maintenance. This Bronco is used in Butte MT during the summer and fall and has been running normally since early July. This is the first time I've seen this problem. (it wasn't just running out of gas or was it?)
After putting 6 gallons in the tank, 2 gallons at a time (the size of my spare gas can), the truck still wouldn't start. It would spin just fine but no hint of a start.
During the troubleshooting I took off the center wire on the distributer to check for spark. There was a surprising amount of corrosion on the center distributer plug. I wiped that off as best I could and tested for a spark by turning over the engine using the starter motor. No spark was noted. I assumed that therefore the coil was bad. I located the coil and check for a spark there. No spark was evident at the coil. I again assumed that replacing the coil would fix the problem and I headed off to the auto parts store and home garage for the part and tools to do the job.
Meanwhile my dad has called the AAA and they towed the truck home. Great, so I get to repair the truck in the driveway instead of at the local game and fish parking lot. It's alot more comfortable where all the tools are close at hand.
So the change out of the coil goes very quickly and when I climbed into the drivers seat I expected the engine to fire up. It didn't. Still no spark.
That left me scratching my head. I had just bought a Haynes manual for the 1990 Bronco, ($0.47 plus $4 for shipping). So I had that to read. Plus I had this forum which was very helpful.
This morning after reading the manual carefully, I started on the troubleshooting procedures outlined in the Haynes manual. The Bronco has a Ignition Control Module (ICM) on the distributer. It has an EEC-IV PCM, i.e. a powertrain control module (PCM). It has TFI-IV with a distributer mounted ICM. All this seems simple now but reading the manual last night was torture because of all the acronyms and not knowing which ignition system I was troubleshooting.
So this morning I was ready to solve the problem.
The first step was to recognize that the fuel pump was running upon turning the key on. That meant that the EEC-IV PCM was getting voltage. The EEC-IV PCM is the expensive computer that coordinates all the running of the engine.
The next step was to attach a test light to the TACH terminal (negative) of the coil and the battery ground. Crank the engine
Now Haynes has three outcomes for this test.
The light flashes brightly
The light is bright but no flash
The light is off or is dim.
Mine showed no flash but it was bright at first and then dimmed. It was bright in the key RUN position, then dimmed in the key START position.
It wasn't what I would call real dim, and definetly not off.
The solution to the first outcome is that the coil is bad.
but I had a new coil so that was eliminated
The solution to the second outcome is the "problem is in the primary cirbuit (open from TACH to dodule) or ignition control module (stuck open transistor). Check primary circuit harness continuity from TACH to ignition module first (see step 16)."
The solution to the third outcome is the "problem is either a voltage supply problem, short or open harness circuits or electronics (no electronic switching). Electronic problems could be bad ICM, no PIP signal (PIP sensor) or no SPOUT signal (EEC-IV PCM) Check coil supply voltage first (see step 21)."
I jumped to step 16 because the intermediary steps were to check the coil.
The primary circuit harness continuity was checked using a VOM. The ground lead was on the disconnected TACH plug at the coil and the positive lead from the VOM was on the number 2 pin (count starts at bottom of ICM plug) at the disconnected plug on the distributer. Reading was less than 5 ohms, so OK.
The reading from TACH to battery ground, i.e. ground lead was on the TACH plug, positive lead was on the battery negative terminal, was greater than 10,000 Ohms, so OK.
Haynes suggests that given the second outcome above the solution is to replace the ICM.
Haynes suggests that given the third outcome above the solution is to proceed to check the ignition control module (ICM) supply voltage.
I wasn't ready to run down and buy an ICM ($60 new) just then so I went to step 25.
I attached a lead to the base of the distributer. I did this by cutting the clamp off an old battery charger leaving a 6" lead where I attached a alligator clamp. The old battery charger clamp was needed to clamp onto the distributer hold down bolt. The VOM negative lead was clamped in the alligator clip. The VOM positive lead was used to probe the 2 and 3 pins of the ICM harness. Voltages did not read as expected. The voltage on 3 pin was not registering and the voltage on 2 was increasing as the key was left in the RUN position. So I'm scratching my head again????? I might point out that I had left the coil unplugged from the vehicle harness
The next step was to disconnect the starter at the solenoid and to test the voltages with the key in the START position. Still no voltage on pin 4.
The voltages should have read within 90% of battery voltage
I reconnected the starter at the solenoid, and it was break time.
After sitting in the shade drinking a pepsi and enjoying the beautifull Butte summer weather I was ready to complete the troubleshooting and get the Bronco running or not.
Haynes indicated that testing the PIP was next.
The first step under the distributer mounted ICM is to reconnect all the ignition systems connectors. So I hooked up the coil plug to the coil and just happened to check the voltage on the still unhooked ICM plug and lo and behold the voltage was within the 90% of battery. More headscratching????
The next step was to put a pin thru the insulation on the reconnected ICM plug number 6 wire (PIP OUT). The top wire in the harness. This pin is connected to the VOM using the positive lead. The negative lead runs to the battery ground. The VOM is set to read Voltage AC. It should read between 3.0 and 8.5 volts while the engine is cranking.
But while cranking, it starts. Problem solved. But I don't know how.
My dad was helping me with cranking the engine. He said first thing in the morning that all that was needed was more gas. So we went down and got 6 more gallons of gas before I even started troubleshooting this morning. The tank now held over one-half a tank, it's a 32 gallon tank. But after putting the gas in the tank it still wouldn't start, hence the troubleshooting.
The Bronco definetely did not have a spark before the troubleshooting began.
But nothing was replaced.
Let me also point out that there was no CEL, no trouble codes, I had them checked at Checker Auto Parts after the Bronco was running.
The Checker counterman suggested that I look at the fuel filter as being the defective part. This might make sense if a half full tank and half a day of sitting floated some blockage away from the screen and allowed fuel to be delivered. But I'm skeptical.
So is it the fuel filter or was there some stray voltage that was holding in the ICM preventing spark? The stray voltage was discharged by the troubleshooting? I would point out that the connections were sprayed with WD-40 as a method of cleaning.
Any Thoughts? Thanks for reading this long post. I hope it makes sense.
The truck stopped again today after running a few miles yesterday. The truck stalled like it ran out of gas. Then when restarted it stalled again quickly and wouldn't start again. No spark situation exists again. Towed back to the driveway again. Tow truck driver suggests bad module due to no spark.
So the question is, Does the fuel filter blockage cause the ICM to block spark?
I removed the Ignition Control Module (ICM) today and checked it. It checks OK per the Haynes manual.
This Bronco is a bear to work on. The distributor needs to be removed to remove the ICM and the screws holding the ICM onto the distributor are a small metric size with a deep hole to reach them. I used a 5.5 mm socket from a precision nut driver set.
The Bronco still has no spark, but my plan is to examine the wiring harness very carefully tomorrow, Tuesday. Remember that I was moving wires when the problem went away before. I'm thinking that I somehow reconnected the loose, frayed, or broken wire that might be causing the problem.
SUP G , To be honest, I didn,t read through your Whole posting [wasn't able to follow along with all the ACRONYMS EITHER]but as far as your corroded distributer wire goes it would be a good idea to give that Bear a tune up....cap,rotor,plugs,wires....might be as simple as that...
Either doesn't have a good ground or is bad and only shows the problem when hot, which is a common problem with this system.
When the module is cold it shows and allows continuity and allows the truck to start, once it gets hot it breaks down electrically and does not allow conductivity.
So I would first suggest you make sure that if you are going to replace this module get the right little module rachet most auto parts stores sell it for around $5.00 then get yourself some dielectric grease for mounting the new module or after you clean up the old one and its mounting surface on the distributor
Mount the new(make sure it's the same part number as the old one) module after coating it with the dielectric grease torque to spec found in Haynes manual and test.
If this does not work change your fuel filter and make sure of the enertial switch is not activated (which can happen from hitting a bump).
I also think a good tune up wouldn't go too far wrong as well as changing the battery cables and load testing the battery and starter often over looked.
It was told along time ago always start at the beginning and never assume anything, and the beginning is always the battery and cables.
If the battery drops below 9.6 volts when cranking the truck will not start due to the engine not turning fast enough to fire.
An easy way to test the starter, ign system and battery if you have your truck is a standard transmission is to bump start the truck by pushing it and pop the clutch or rolling down a hill and pop the clutch if it starts then you know you are looking at battery or cables or starter or solenoid problems.
I got the distributor in the right spot. While testing the ignition timing I found that I didn't have a timing light when the SPOUT connection was removed (per Haynes manual when setting timing) but I did have a light when the SPOUT connection was installed.
Haynes manual suggests turning it over to someone with better testing equipment and the PCM EEC-IV computer may be broken.
I have a simular problem with my 95 5.8. At first it would stall out, just when ever! Maybe once every two weeks, but would start back up right away.
Then sometimes it would take three or four tries before it would start.
One morning it wouldnt start. When I got home later that day it started right up!
A week later no start again! So I replaced the ICM and it started right up! Ran good around the block untill I went out for a test drive and something to eat. It started and then stalled out and would not restart! I left my cell phone at home so I just sat there for about twenty minutes. I tried again and it started right up. Drove home and the next day again no start. So I got another ICM still no start.
I fiqure the only thing left is the distbutor. So I got a rebuilt and changed it out. It started right up and ran good.
Next day it started stalled out and will not restart! I'm out of ideas. So before I have it towed to a shop does anybody have some better ideas?
I would suggest changing spark plugs. I would also check the fuel supply for proper pressure. My problem was solved by rebuilding the distributor with all new parts, armature, cap, rotor, stator, ICM, coil, spark plugs. And the ground, distributor to engine block, should be checked when replacing the distributor.
rudedogii I fought the same issue for over a year and think I have it fixed. Codes were 211 and/or 212.
You can do search and find my posts ad nasium or here is a summary.
I replaced black ignition control module with a gray one and it took me forever to realize my error. SEE SIGNATURE BELOW. If yours is black don't look for a bad resistor in the wiring harness. It is is in the black ICM.
The ground stud on the fender next to the battery was turning in the fender and the two eylets on it were also loose. Made a new ground stud. Cleaned all the grounds I could find. I wish I had found this before installing the wrong ICM.
Opened all the wiring harness, found nothing.
Three rebuilt distributors, still stalled.
Coil terminal was half gone. Went with Blaster coil, Ford Racing 9mm, Copper plugs and still stalled.
Two new gray ICM, still stalled.
Black ICM from a Taurus on eBay runs cool. Gray ones would burn fingers.
ECT and ACT were telling computer the engine was not warmed up and it was thus running rich. IAB was stuck closed and caused rich idle also. No code on these but replacement of these three made a big difference. Still stalled. It was also still bucking at 1,700 rpm light throttle.
Oxygen sensor is supposed to be changed at 60,000 to 100,000 miles. Again no code but replacing made a HUGE improvement. No more 211 or 212 codes nor bucking. No stall yet.
New code 172, lean oxygen sensor at light throttle above 40 mph and CEL light but continued to run. Replacing 460 air inlet tube with stock one over the radiator fixed it. Engine runs GREAT. No stall yet.
200 varied miles and no stall but have not had the 90+ high humidity day when most of the stalls occurred.
So the answer is... grounds, four sensors, correct ICM....perhaps. We shall see.