Situation:
Drove the car a couple of miles to the post office. Upon pulling into a parking spot, the car appeared to stall. Wasn't 100% sure it stalled as I was just turning the ignition off, so went inside to take care of business. When I came back out, the car wouldn't start - crank but no ignition. Checked engine bay, couldn't see anything wrong, battery was fine and no leaking fluids, so called for a tow (bump/jump starting wasn't an option).
While waiting for a tow (about 30mins later), I tried cranking again and it started up - drove home quickly and it died twice more on the way, but managed to get it into the garage. Car stalled a couple more times in the garage, while I was trying to replicate the issue by working the throttle linkage in the engine bay (revving to 3-4k). Found the vacuum line for the interior temp sensor in the engine bay was disconnected (I believe this can cause a vacuum leak) so reconnected. No change.
Right now, the car will crank and nothing more. I'm wondering if the issue might be related to the Motronic - this seems odd, given it's a new (refurb) unit and I'm not sure it would fail in a progressive way, with the engine cutting out a few times before dying 100%? As always, I look to those with more experience to help get this properly diagnosed.
Issues I've found:
- There's no spark - pulled a plug and I can't see anything when cranking; per old thread, these are new (<2k miles plugs) and don't appear fouled
- The fuel injector plugs aren't getting power - I checked 2 of them - this is weird, given the ECU harness shows power to the injectors (see below)?
- The 87 pins on the main relay aren't getting power (again, see below)
- Battery is good - it's <1yr old and the car lives on a tender when not in use
- Fuses are all good and seated properly
- Ignition coil resistance readings are within spec (0.7 ohms and 5300 ohms)
- There's voltage at the FI temp sensor
- Fuel relay has been tested and is good - I've checked voltages and jumpered the pins; I can hear fuel being pumped around
Main Relay:
- I don't believe the main relay itself is faulty, as I can hear the relay click when plugged in, if the ignition is on.
- I jumpered without the relay (3 way, 30/87/87) and tried starting with both the fuel and main relays jumpered, no change
- Further testing showed there's virtually no power (0.72v and 0.03v) to either of the 87 pins; I am seeing 13v to pin 30 and 12.9v to pin 86 when the ignition is on/off; (I've tested from the underside of the connector as well, just to be sure)
- From reading the ETM, the red/white and blue/red wires from the 87 pins go to the ECU for power, the fuel pump relay and injectors
- With the ECU disconnected, the ECU harness shows 12-13v power @ pins 35/18 (power inputs), 20 (fuel pump relay control) and 14/15 (fuel injectors)
Let me know if you have any thoughts as to where I can go next
Thanks