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1990 Bronco, 5.8 EFI. This is a new eng with about 3500 miles on it. I'm driving along today and she just quit running. I was going about 45 and the eng quit. It turns over and cranks, but will not start. Here is what I've done so far:
Plugs and Distributor are new, replaced the ignition module- still nothing
The rotor turns so I have ruled out the timing chain
Ran codes on the ECU and get code 111 (system pass)
I have fuel pressure (relief valve on fuel line will spray fuel when pressed in)
Tried another ECU from an 5.0 and still nothing.
Inside of distributor is clean and dry, all wires are connected.
It sounds like it isn't getting spark, - maybe I am forgetting something here!
You could take a spark plug out, reconnect it to the plug wire and ground it to the block to see if its getting spark. I would recommend using pliers with rubber handles to hold the boot and plug as you ground it, IMO its easy to give yourself a jolt when grounding it by hand. Let us know what you find out. Sounds like a bad electrical connections somewhere. Has anyone replaced or modifed any thing in particualar on the truck before this occured? Good luck
just spent whole day trouble shooting with no progress
Kemicalburns: No, I'm using the 351W ECU.
Here is what I did:
Tested the spark plugs with spark tester: no spark what so ever is making it to plugs.
Tested the new ignition module I put in yesterday - 12V DC is making it to the Distributor when key is on and 10V is making it when the key is in start position. According to Chiltons manual that is acceptable so I replaced the rotor and cap. Still nothing
So I am at my wits end here.
Background on this bronco is I completed an eng swap about 3 months ago and the thing has run great ever since. All new components (plugs, ECU, Wires ect...) Then she just quit.
What else could this be?? I know it has to be electrical. Right? Could the actual ignition switch on the steering column be bad? There is a lot of play and that is the only thing I haven't changed out.
Could my wiring harness be bad? I kept the 302 harness from my eng swap.
Appreciate any advice -- this is frustrating to say the least
the coil could very well be shot, double check it. but it could be something as simple as an ignition fuse as well. follow all the wires that involve the ignition and make sure nothing is burnt/bad or strange lookin. also there might be fried fusible links, although im not real sure about that. but the the most likely thing is the coil, good luck
turned out to be the Ignition Control Module that is side mounted on the Distributor. Man what a pain in the a$$. I never knew these could cause such a problem. Mechanic down the street said that it is very common for the ICM to just stop working.
Oh and don't forget, if you ever have to change one, get the "special tool" that is required to unbolt the module from the distributor. It will save you a frustration look through your tool box for the right socket (which you will never find). The tool costs about $8 and is a special socket that will fit through the small hole to the recessed bolt. With out this tool you will not get the ICM out.
On a side note, I've read in one of my 302/351 EFI books that it is not recommended to check spark by grounding to the block or holding the wire next to the terminal. The sparks can cause the TFI module to be unhappy with your procedure and damage it.
For 2.99 from harbor freight tools, I got an inline spark checker. You put it inline of the wire/plug and it has a light that flashes w/ the spark. It'll show bad/poor spark...or no spark...kinda nice.
good to hear you got it figured out, i forgot that the pre 92 trucks had TFI-IV distributors on them. make sure that u put some dielectric grease on the backside of the new one so it can stay cool, when u put it on. the chevs HEI ignition has the same problem with that sort of thing. theyre exposed to alot of heat and vibration because of their location. so they tend to go out more than ones that are remote mounted. well good luck