Solo2fan

Guys,

I need a sanity check to see if I’m on the correct path fixing a no start condition.

Stock 92 TPI/700r4 in a 1961 Chevy Short Wide. I built it about 10 years ago and has been trouble free until now. AUJP bin with vats and air delete. 122730 with NVSRAM mod.

Below is what I have tried.

*Crank but No start.
*Has spark at coil and number 1. Swapped ignition module and coil because I had them and was planning on replacing the 25 year old parts. No change.
*Has fuel pressure at rail ~40psi
*No trouble codes
*12 volts at injectors both sides
*All injectors ohm out at ~16 ohms
*ECM continuity between injectors and engine ground verified at ECM pins.
*Motor runs with starter fluid.
*Grounding ECM side of injectors fires motor on crank.
*TunerPro data stream looks normal for everything including throttle Position sensor (read this can cause no pulse. Not sure if true)

Based on the above I thought the ECM injector driver had failed. The truck had been bucking intermittently at odd times a few weeks before it died.
I ordered a 122730 off eBay and installed with a new burn EPROM setup with AUJP with vats deleted. Verified vats 46 code given before deleting it. AUJP was pulled directly from the original MEMCAL. The failure mode did not change with the new used ECM. I revisited all the above steps and have come to the same conclusion that the ECM driver is bad so I must be missing something that can cause the injector grounding signal not to happen or the injector driver FET is a high failure part and I got another bad ECM??????? Any idea’s. I have a third ECM on the way but I’m not holding my breath.

bigal55

iTrader: (1)

How's your ECM ground? You have ground wires to the ECM and the ECM case to dash grounds? You can check the injector pulses right at the ECM, see if you are getting pulses there. This will eliminate any wiring faults between the ECM and injectors and ground. If no pulse there, could be between distributor and ECM or something in the distributor. HTH!

mcgarnicle

iTrader: (14)

When you're cranking are you getting a tach signal? Normally while cranking the RPM gauge will bump up and down. If it is not moving at all while cranking it is probably your pickup coil in the distributor.

Solo2fan

I did not look for tach movement. I will check tonight but I assume it does because I'm getting spark and it runs with starter fluid.

mcgarnicle

iTrader: (14)

Did you fix it?

Solo2fan

Tach was moving. I swapped the ignition module again and now its running. The bad module I put in was firing the plug wire with a screw driver to ground when I tested it but it must have been random. And with starter fluid it did appear to fire but I did not run it more than a second .... Odd. But it's running fine now. This will make the third bad ignition module I have had over the years but the first bad out of the box.