85 Eta, Fuel but no spark

[acalora]

I swapped those sensors with brand new ones already. I disconnected the old ones to check ohms and the connectors just crumbled.

[RobDog]

Do you have a Bentley and have tried the electrical test on the harness at the ecu from the Bentley diagram?

[acalora]

Yeah. Tested and have power at 18 and 35 even with ignition off, donno if that's normal. Have starter power during start. Have continuity between the spark output of the ecu and the coil. Also checked all grounds. Check fuel injectors and fuel pump. All electronics check out

[RobDog]

I'm out of idea's. I hope its the obc relay or something simple. Its weird that you have power at both pins. I thought one pin had constant power and the other was switched power?

[acalora]

Yep, I didn't expect it either. Took the main relay out and power to both pins disappeared. Put it back in and I got power again. Didn't hear the relay click though. Maybe a bad relay? I replaced it back in November.

[RobDog]

Do you have the correct relay with two pin 87's and no pin 87a?

[acalora]

I'll have to check. I'm actually not sure. I didn't know that 87a was different from 87

[RobDog]

ya, the main relay should turn power on to 2 pins/wires and not switch between pins. That may explain power on both pins 18 and 35 of the ecu. Also no spark because only half the ecu would be getting power when cranking.

[acalora]

You made me get outta bed for that one. A quick bench test and it does indeed switch outputs. 87Q (which is how its designated on my relay) is on when the coil is not active. Once the coil becomes active, 87Q shuts off and 87 turns on. Ignition off and I get power to the ECU, ignition on and I don't get power. We may have figured this one out. I'll be up before dawn to grab a new main relay and have this running good and well by the morning.

[RobDog]

Turner motorsport has a good photo of the correct relay. It shows the correct configuration with the 2 pin 87's. That may help explain things.

[RobDog]

Good news!

[acalora]

Yeah I've got a good handle on what to look for tomorrow. Just gotta make sure both 87s are on and off together. I will update tomorrow if this relay is really all we need to fix.

[RobDog]

That is exactly what you need, both 87 pins to turn on and off together.

[RobDog]

I thought I had read somewhere that in an emergency the fog light relay? or another relay in the fusebox could be used because it has 2 pin 87's. Im not certain on which relay so I would check the relays or google it.

[acalora]

Well the car starts now. It runs pretty poorly, but it's what you can expect from a car that hasn't run in 10 years. For anyone troubleshooting and reading this, do check your main relay and make sure it's not 87, 87a and that it is 87, 87. Thanks so much RobDog