Potential Fuel Injection Issue - Help w/ Diagnosis

[t00nces]

Cross-posted from Mirafiori:

Greetings experts,

I'm nearing the finish line with a complete rebuild/restoration of my '81 FI 124 Spider and I've run into a potential fuel injection issue that I'm hoping to solicit some diagnostic advice. First, the details on the build:

1981 FI Spider 2000
1.8L Head - ported and polished
10.8:1 Ross Pistons and rings
Cone air filter - attached to stock Air Filter\Air Flow sensor
123Ignition+Tune Distributor
Allison 284 Street Cams
Allison Performance Intake (43mm) and Exhaust (37.5mm) Valves

The issue:

After setting the static timing and setting the 123 to 10 degress advanced, the car wants to start but seems to be fuel starved. Using a little starter fluid sprayed into the air filter mechanism (air filter off), the car fires up and runs very well for 30-45 seconds before stopping. Feathering the accelerator doesn't seem to keep it running and once the starter fluid dissapates, the engine stops.

Diagnostics to-date:

Following Brad's Bosch FI Diagnostics Guide, I have tested all the componants as per his instructions:

Fuel Injectors - new and confirmed voltage and confirmed pulsing
Cold Start Valve - confirmed spray when cold
FI Resistance - confirmed at ECU connector
Throttle Position Sensor - confired working and set to close as per guide
Lambda Sensor - replaced w/ new
Fuel PSI - confirmed at ~26PSI at fuel line attached to Cold Start Valve (post fuel regulator)
Fuel Pump - new and confirmed working (tested by manually opening Air Sensor flap)
Relay - new
Hoses - vacuum, air flow regulator, etc. new - no leaks

After a little Google-Fu, I came upon this diagnostic - https://centerlinealfa.com/tech_bosch_injection The section that caught my eye was this:

Diagnosis of a No Start Condition (L-Jetronic)

This is a short guide to some common causes for a no-start condition. It is not a complete listing or a substitute for a proper shop manual.

Voltage. One of the design parameters of the L-Jetronic system is that there must be 10 volts on the #10 pin connector at the ECU for the car to start. If there is less than 10 volts, the ECU shuts off. This requires a very good battery because the electrical load during starter cranking can cause the voltage to drop below 10 volts at the #10 pin. Check your battery condition and battery/ground connections first. Once you’ve determined that the battery and battery cabling are in good shape, try the following. From the #10 pin at the ECU connector, trace back into the harness (green/black wire) as far as possible. You will need a couple inches of wire. Cut the wire and tape it off going into the harness. Now, locate the main power relay next to the ECU. It has a large gauge red main power wire going into it. Take the wire from the #10 pin on the ECU and attach it to connector #87 on the main power relay. This provides more voltage to the starting circuit.

After referring to Brad's Electrical Wiring guide, I don't see any reference to voltage to #10 on the ECU Connector and the colour coding of the wires to the relay doesn't match to what's in the Electrical Wiring guide. A quick check to see if there is any voltage to #10 shows that there's no voltage on it - in run or start/run. However, because it's not noted in Brad's guide, I'm not sure that information on that page is correct.

Logic would seem to dictate that if the injectors are pulsing and that all the other systems check out that *perhaps* the injectors are not firing and thus, I'm not getting fuel into the intake.

Before I remove the injectors and test each one, I'm wondering if I've overlooked something else. Any and all advice greatly appreciated.

Regards,

t.

[18Fiatsandcounting]

I have essentially zero experience with fuel injection so I can't offer much, but just a thought: 30 to 45 seconds is a long time to be running on a spray of starting fluid. Even when I've used a pretty vigorous spray of fluid, it only runs for 5 seconds before cutting out. Maybe 8 to 10 at the very most. So, could part of the puzzle be that the fuel injection is working for 30 to 45 seconds but then stops after that for some unknown reason?

-Bryan

[Nut124]

How did you set the ignition timing if the engine did not run? Have you checked timing while cranking?

How did you assess that the engine "wants to start"? With your high CR, the starting fluid could ignite w/o spark.

[t00nces]

Thanks for the replies!

I should have been clearer - the spray was fairly continuous. Timing was statically set and then checked with the timing light while the car runs/cranks.

I think the issue has to do with the snippet I published. I looks like there is supposed to be power to #10 on the ECU connector and that's triggered by the flap in the airflow sensor. If that doesn't open, the ECU doesn't trigger the injectors.

Regards,

t.

[BellaMacchina]

What could also be the issue:

The 123Ignition+Tune Distributor provides a theft lock feature.
If locked, it allows the engine to start and after about 30 seconds, it turns the ignition off.
Maybe the lock is active ? Just check in your app.

I would also check one spark plug directly while running (to ensure the 123 is not doing weired things). Does it stop firing after 30 seconds ?

Regards from germany
Markus