Alright internet friends, I need some help diagnosing a no-start condition now. I'll try to be as thorough as possible in the explanation so bear with me:
Background:
The car has idled rough since day one. Occasionally stumbled coming off of idle, but would usually run past 1500rpm or so.
Sometimes the car would die when coasting to a stop.
Partway through our latest rallycross, the engine developed a pretty serious hesitation below about 4,000rpm and was noticably down on power.
Today, I went to take it for a quick drive and when I pulled out onto the gravel road in my neighborhood, it died.
I went to start it again, it would crank well but no start. I also noticed that I could no longer hear the fuel pump kicking on.
My troubleshooting:
Rather that my typical approach of throwing parts at the car, I decided to dust off the multimeter and try to actually figure out whats going on.
1. Unplugged the fuel pump, turned the key to "on", saw zero volts across that connector.
2. Swapped the fuel pump relay with a known good relay; no change.
3. Bypassed the relay with a jumper wire and heard the fuel pump kick on.
4. Signal wire at the fuel pump relay had zero volts regardless of key position.
5. I happen to have bough spare "main" relays and swapped one of those in, still nothing.
6. Turned on the fuel pump with that jumper wire and tried to start the car: Same thing. Cranks well but no start.
at this point I assume there's no spark, but I live alone and couldn't come up with a clever way to test spark by myself
7. Crank position sensor is a known failure point on these cars. I test resistance and it is in range, no wires look frayed, but the sensor is real dirty. I clean it off and still no change.
So at this point I'm starting to run out of electrical troubleshooting abilities. Could it be that the ECU itself is dead, with that death being accelerated by vibrations from rallycross and dirt road? Is it worth getting a new CPS to swap out? Am I missing something obvious?
[e30 fuel pump wiring diagram for reference]