Car wont start - I tried it all
 

Hey y'all sorry this may be a long post but I'm lost at this point.

I have a ‘96 NA that seems to crank but does not get fuel, no spark and no check engine light. Everything was working fine, cruising along and all the sudden power was lost. It hasn’t started since. I’ve followed the previous guides for troubleshooting a no start situation and the car still doesn't start.

So far I've also done:
1. I’ve checked and replaced the EFI relay which does work and click. I’ve checked that the relay is getting power at the NO and COIL sides when supposed to.
2. I’ve checked the ROOM fuse under the driver door and the fuse is intact and getting power. 3. When I bypassed the fuel pump at the diag box I heard it come on but still no start.
4.I also used a spark plug tester and it received no power.
5. Another ecu was installed as prior one had corrosion and broken resistors etc.
6. I pulled up the pinout for the ECU and saw 12v being delivered.
7. I've disassembled the ecu and all the capacitors and resistors look fine.
8. I get no read with my OBD2 scanner which makes me feel its more an issue with the ECU? If anyone has any other ideas or recommendations before I shell out for an ECU that would be greatly appreciated.
7. I’ve replaced all the fuses in the driver fuse box and inspected and checked all the engine fuse box fuses with my multimeter for a second time

Guys and gals I'm running out of ideas and am really hoping one of yall have something that can get me out of this mess.

Not trying to say this rudely but it does crank, correct? If so, does it crank at normal speed? Just want to get that question out of the way before dithering down the wrong path here.

You said no fuel and no spark. Is the fuel pump failing to come on on while cranking or are the injectors not firing?

Given there's no spark present (and possibly no injector pulse), my interjection would be to check and see if the ECU is receiving rpm signal from the CAS during cranking. However, I just re-read your post and saw your scanner won't communicate with the ECU. Can you confirm your scanner will communicate with a different vehicle? I'd try to diagnose the OBDII port issue before anything else so you can at least try to get a little more information via the scanner.

I don't have my manual/wiring diagram on me but I'd bust out a multimeter and check if you have power present at the OBDII port. If you can get the scanner to communicate with the ECU and see if it's receiving an RPM signal, that will help further narrow things down.

So, to clarify:

1) This car was running fine, driving along, and died.

2) After that, it will no longer start.

My thought would be timing belt snapped, but also let’s go back a couple of diagnostic steps and start with some basics.

1) Charge the battery to full. You’ll want to ensure it’s fully charged throughout the diagnostic process.
2) Crank the motor and verify that you have motion on the front crank.
3) Remove the oil filler cap and crank the motor. Verify that the cam is turning.

If you can't talk to the ECU, it's probably not getting power and ground. You report it's getting power. I'd check all the grounds next, maybe a dirty or loose ground wire is the culpret.

You'll need OBD II comms established before there's any hopes of it getting fuel and spark.

There are only a few wires for power and ground required for the ECU to turn on. I'd check every one is correct. GND wires should beep if you use a multimeter set to continutity and touch between those wires, and the chassis (chassis is electrically connected to battery negative by design).

Hey guys, thanks for the good advice.

So far, I’ve charged the battery and cranked the car fully charged. I saw the cams turning which checks that off.

I pulled out the wiring diagram from mullens and checked all the grounds I could find. They’re all beeping and continuous.

I tested the delivery of power from the major fuses (room, stop and main relay on the ecu side. Then found that the ROOM pin (4I aka blue/red) is not getting power. There is power at the drivers side fuse box and in the ROOM fuse slot. The fuse is intact so makes me think it’s the wiring. What do y’all think?

So I followed the ECU printout and it all checked out power being delivered (12.6 - 13v) and continuity when it's supposed to be ground.

I did something a little extreme to confirm too. I took the ECU out of the metal enclosure and checked to see if the power was being delivered to the individual socket pins on the ECU. To my surprise they were getting power. I feel like that means the ECU itself is the culprit. Which seems weird cuz I couldnt see any burnt or bulging capacitors or resistors. Now I'm trying to source another ECU just to test for cheap/free with little luck. if I can't manage that, I'm considering buying a Megaquirt or SpeedyEFI PNP ECU and see how that goes. I think I should be able to read them even without the car running which could give me a clue?