Technical No pulse to FI

[joerealtor]

Hello all and thank you in advance for your assistance. Here is what I have, 82 Spider with no pulse to FI. Already ran through the diagnostic and had issue with #19, showing need for new ECU. Had a spare but does same thing. Car starts off of cold start valve and runs for a few seconds then dies. Fuel Pressure is 32. AFA turns on pump. Just no pulse. Changed out dual relay and still nothing. At a loss. I don't think it is very common to have 2 bad ECU's. Any ideas.

Btw, have pulse to cold start, just nothing to other injectors.

 

[spannerdude]

I'm assuming it's L-Jettronic with a moving flap airflow meter.

Are you sure that your problem is with injector pulse, have you checked this with a dwell meter?

The symptoms you describe sound like the airflow meter. The fuel pump runs when the starter is cranking. When the engine fires up and the airflow meter opens, this operates the pump relay and takes over from the cranking feed. If the airflow meter is defective or stuck the engine fires up on the starter but dies a few seconds later when the pump stops again and fuel pressure subsides.

You can test this by taking off the induction pipe and opening the air flap with your finger. With the ignition on you should hear the fuel pump running.

 

[joerealtor]

I have checked the airflow meter. Moves freely and pump turns on. I have a complete set of fuel injector testers. No power at all going to injectors. If it was constant power I would think the ECU. I get pulse to the cold start, but not the other four injectors. I am getting spark, but not seeing the pulse in the the brown wire from the coil, like I should. Just a constant power feed. I am now thinking that the coil may not be sending the signal the the ECU which in turn signals the injectors. Putting a new coil and control module on tonight and check the grounds there.

 

[GeorgeT]

Think bad Double Relay: one side controls the fuel pump and the other side is for the injectors. This is not an uncommon failure.