no start; 1988 carb. dist wire to ecu showing resistance

[tooldude]

I have been thinking about this and trying to come up with something. Some of this has been mentioned, but going through it may hit on the problem or cause you to think of something else. I believe results have shown that disconnecting the FBCA will affect the fuel mixture so that idle is not achievable, but not enough to prevent running off the primary port. This is caused by disconnecting plug #3, but that does not remove power from the ignition, which was all that was needed to run the engine as you did. Can connecting plug #3 pull down the voltage at the coil enough to cause a no start? Wouldn't a short that big would blow the 10A engine fuse or require the battery to be too weak for cranking? Could it add enough additional current draw to drop coil voltage? Maybe, if there is resistance in the ign. switch and/or main fuse link, splices, and connectors causing borderline voltage drop - checkable by running B+ directly to the coil; or the battery is somewhat weak and/or the starter/solenoid are pulling excessive current - checkable by jumping the battery. How else could connecting plug #3 cause a no-start? The ECA and emission control system do not prevent the engine running (somewhat), as we have seen. What can the ECA activate that may kill the engine? The Decel Fuel Shutoff Solenoid may be activated, shutting off fuel. Try unplugging it. I hate to think about hidden wire shorts in the harness and bad ECA's.

[katscan]

ok, this is what I found today; The ECu has three plugs (yellow) the left most plug removed and the car will start. O volts at the blue orange wire at dizzy. Plug the yellow plug up; 12 volts at BL/O at dizzy. Disconnect tach; still 12volts at the dizzy; car wont start. Looking at the ECU plug there are two hot wires....BLK/W and White/Red. i removed the W/R from the connector and plugged into ECU...still 12v at dizzy; no start. Put Wht/red back into yellow connector then removed BLk/W from the connector and plugged into ECU.....0v at dizzy and yes; start!. That BLK/W wire goes to the headlight switch relay and the wires going to it are Yellow/Grn, Black/Red, White/Blue, and BLK/wht. Thats a tach wire I think going to that relay. I don't have resistance at the relay coil , so it is bad, and will replace. I am getting closer. thanks again and will keep everyone helping the results that I find. I have to retire now to eat and sleep; working 2-3rd every night.

[tooldude]

I believe that's the EFE Heater Relay you found. That Y/GN wire should not be connected to the tach Y/GN wire. So the ECU was not getting B+ from the BK/W wire? Did the engine run normally and idle with that wire connecting?

[katscan]

Well, the white blue wire goes to the headlight switch; it is power under the hood ptc. The relay uses blk/rd and yellow grn as the coil. the coil resistance gone; therefore blk/red from ign switch in contact with a negative yelow/grn. The Blk/rd also shares the lead with the blk/wht; therefore blk/wt, blk/rd, yellow/green all making contact at the same time. Therefore ,If you have a "no spark issue", that relay is something to look while doing all the other normal things. The car starts, I dont want to jump power yet to the Blk/wht. Gonna wait on the relay. This blk/wht wire gets its juice from the white/blue wire. There are other blk/whts too; this might be a separate circuit; don't know;
On another note, about the idle, car wont idle cause there is no blk/wht power now to the ecu. that comes with the relay. That left most ecu plug is the stepmotor function that controls idle. It ran flawlessly until the car died. I expect it to be no different......HOWEVER, I know better than to ever try to test solenoids, I wanted to hear them click, and yes, I sparked one.....That usually is instant death. I did that early morning before I found the problem. So, I am looking for sure for the fcba stepper motor. Please help me find one. Thanks million. Jeff

[tooldude]

I believe you need these wiring diagrams from the 1988 EVTM.

[tooldude]

[tooldude]

If the pictures don't copy & come out clear I can try to email the full size to you. At least you can see there is no headlight relay on the stock carbureted car.

[tooldude]

After spending hours with my computer & these pictures, I took a look at your post. Looks like you're getting connections through that relay that shouldn't be there, so I'm thinking there is shorting in the relay. It's only running the ptc heater, so you should be able to pull it out and see if the engine runs right with everything connected back.

[katscan]

Thank you for spending time on this; yes I do not have any diagrams. That relay is the PTC. The coil is bl/rd, and bl/wt. switched legs yellow green and white blue. White blue goes to hazard switch and yellow green goes to instrument cluster plug. Blk/w gets power from ign. Not sure what bl/rd is yet. Thanks for the help and diagrams tooldude. I am going to order that book; It looks like thats what I need. Definitely would have saved me some time! LOve the festiva.
Thanks dude. Tooldude.