Chasing missing 2.9 spark

[old409]

I'm using the TFI Worksheet and everything checks out but my lite at the coil plug doesn't blink (no lite at all) when I crank the engine and the ignition ground on the TFI connector that plugs into the distributor reads infinity (no ground). This is the Black /Orange wire and I traced it back into the EEC box.

So far I have swapped out the whole dist. with a working TIF module, and a new coil I had. Still no spark. I had the dist, ignition module and coil, everything but the EEC. Is this a case of having everything but the right thing or should I look for something else. Forgot to mention. I've cleaned off all the ground wires I could find, put star washers on them and tightened them.

 

[Sasquatch_Ryda]

I know my buddy had a 2.9L in a BII that we could not for the life of use figure out why it had no spark. Replaced dizzy, TFI and coil with known working units with no results. Finally replaced the PCM, found that the windshield was leaking and the PCM was absolutely green inside. Problem solved. Might want to pull the PCM out and check and see if its badly corroded.

 

[old409]

I pulled the PCM and checked it out. It's clean as a new one. I replaced the on electrolytic capacitor in it because my grandson had a Talon and that's what fixed it. But, no luck with that.

I'm thinking it may still be the PCM/ EEc or whatever it's called because the black/orange wire on the TFI plug is supposed to be ground but it's open and it goes to the PCM/EEC ,so maybe that's where it gets its ground. I hate to blow the money on a new PCM but it's looking like that may be the problem.

If anybody has any suggestions, I'm open to trying anything. This months SS check is already gone so I have a month to screw around looking for something else. Time is one thing I do have.

 

[old409]

I'm still trying to find why I have no spark. I replaced the coil, the eec, the eec relay, the TFI, the pick up assy in the dist., traced the wiring for continuity, redid all the ground connections.

I used the tech sheet on the forum to check the TFI voltages and I have everything but the PIP. It's supposed to be 6 or 7 volts and I have 11. I used the light tester on the side of the coil where you're supposed to have a blinking light and I have a dim light, no blinking. I'm about nuts trying to find this problem. Has anybody ever run into something like this taht had a crazy solution.

 

[IMenriched]

I'm still trying to find why I have no spark. I replaced the coil, the eec, the eec relay, the TFI, the pick up assy in the dist., traced the wiring for continuity, redid all the ground connections.

I used the tech sheet on the forum to check the TFI voltages and I have everything but the PIP. It's supposed to be 6 or 7 volts and I have 11. I used the light tester on the side of the coil where you're supposed to have a blinking light and I have a dim light, no blinking. I'm about nuts trying to find this problem. Has anybody ever run into something like this taht had a crazy solution.

frustrating for sure...
have you checked the ground from the cab to the chassis/engine?

outside of that....seems you're down to checking individual wires in the harness for frayed/chaffed/broken wires and or connections and make sure that you're not getting a "push back" within the connection itself

 

[old409]

I checked the grounds, even took them off, soldered them and used serrated washers to make sure they had a good connection. I checked the wires on the plug that goes to the eec, the TFI and the coil. Next is the plug that goes through the firewall. I'm starting to think I got the Ranger from he77. I've had it 3 years and it hasn't run more than 3 months. I'd get rid of it but I have too much in it.It was supposed to be my retirement truck but it sure keeps me from being retired.

 

[IMenriched]

I checked the grounds, even took them off, soldered them and used serrated washers to make sure they had a good connection. I checked the wires on the plug that goes to the eec, the TFI and the coil. Next is the plug that goes through the firewall. I'm starting to think I got the Ranger from he77. I've had it 3 years and it hasn't run more than 3 months. I'd get rid of it but I have too much in it.It was supposed to be my retirement truck but it sure keeps me from being retired.

I take it that this thing won't start at all...weak spark and all.

can't vouch for your vintage, guessing wiring prolly changed....but mine (86') has a resistor (molded inline) in the wire from the coil to the distributor....green wire I believe. that went bad and had similar consequences...actually the original wire pulled out...so i wired it direct , bypassed...then had very weak spark to no spark too. may have run briefly...too long ago, can't remember exactly....it may have taken the hall effect sensor/pickup coil out, (inside the distributor) & it may have been iffy before too...anyway... I swapped one (the resistor) from a the donor I had at the time and put in a new hall effect/pickup coil in and it ran better than before....not sure what really did it. But the good news is it has been running strong ever since.

Some others here have stated to make sure that the braided ground strap from the windshield wiper motor to the cab is good too...& claim that helped too.
There is a bunch of grounds on these ...umm retirement projects...and I also had doubts as to if 1 ground was questionable some how the other would pick up the slack. So it wouldn't surprise me if that holds true. My greatest gains of runnability came with going over the grounds.

Sounds like you covered that ground arena pretty good though.
and then your back to doing what your doing checking wire. prolly going to have to peal apart the harness or swap out sections of harness from a good one.

sorry not much help but sounds like you'll find it

 

[old409]

I found my missing spark. First the TFI module was bad so I got a new one. Still no spark so I got a new computer and still nothing. I traced all the wires, checked for continuity etc. ,everything was fine. I checked voltages at the computer and they didn't look right so I exchanged that computer. Finally after two computers I got my spark back. During all this, I also got a new eec relay that only lasted a couple days and caused me some grief. Moral of this story is, don't trust new parts.

For anybody having this type of problem, the factory electrical and vacuum trouble shooting manual is the book to have. It breaks all the circuitry down and shows the splices and plug locations. It really simplifies troubleshooting. You can usually find them on ebay for $10 to $20. I now have the Ford factory manuals, Haynes and Chilton's. I plan on this truck outlasting me. I'm 66 so I hoping the truck will last another 40 years or so.

 

[IMenriched]

PTL! glad to see that you are back up and running.

electrical issues can be frustrating to say the least. do you think that the eec relay was not getting proper voltage?.... or was not sending proper voltage out??? that may have cause odd readings through the main ecm/computer.

 

[old409]

My original eec relay was good but I had taken the cover off to make sure it was working and then decided to go ahead and replace it. The new replacement, a BWD part from Advance wouldn't start the truck, the coil part of it was open. I took it back and they replaced it and the replacement was open too. I then went to Auto Zone and they couldn't find the relay listed on their computer. They probably are the same thing in a different box.

Right now I'm using my taped together original. I think I may get one from the local junk yard. I have had two defective computers and two defective eec relays while trying to get this thing started. I'm an old guy and I'm used to getting good working parts in the past. I never dreamed there was so much defective junk being made. No wonder all the companies are moving overseas. These defective parts had made in the U.S.A. on them.

I read somewhere on here, I think, that the best parts were original. But, my local Ford dealer couldn't find his own nose in a well lighted small closet. I'm thinking my best option is the local "You Pull It." I've had to return almost half the new/rebuilt parts I've bought in the last 2 or 3 years. Anyway, it's a big relief to finally get my truck going.

 

[holyford86]

...I read somewhere on here, I think, that the best parts were original. But, my local Ford dealer couldn't find his own nose in a well lighted small closet. I'm thinking my best option is the local "You Pull It." I've had to return almost half the new/rebuilt parts I've bought in the last 2 or 3 years. Anyway, it's a big relief to finally get my truck going.

I've had the same luck with aftermarket parts, I have found myself replacing my replacements with the stuff I took off and replaced before I knew how to properly diagnose things. I have been greeted with a better running engine too.