1g 91-94 ecu - start and stall

[tommyp]

Thread post says it all. This 91-94 eprom ecu is of unknown origin. The original eprom is still soldered in. When ignition is on, the boost gauge moves to center position. In the start position, the FP relay clicks on. On a regular start, the car fires up properly and engine runs smooth, but a few seconds after it's started, the FP relay clicks and the car stalls from lack of gas.

Here's what I've done.

• Changed caps
• Cleaned up residual acid with a thorough wash of alcohol and flux remover.
• I've seen plenty of ecus over the years, and this PWB is in pretty decent shape.
• IC110 and IC111 were successfully tested in my IC110/IC111 socketed test bed ECU.
• Continuity exists between ECU pin 63 & IC110 pin 4
• Continuity exists between ECU pin 110 & IC110 pin 1
• Continuity exists between IC110 pins and "other" end of the printed wiring board copper trace.
• IC109 replaced with working one.
• The trace under C106 was repaired (not associated with the FP relay)

I've read that the ECU needs to see the CAS pulses to keep the FP relay pulled in. The ECU has to be seeing the pulses otherwise the thing would not even turn over. I've traced the CAS trace pretty far in and it appears to be intact.

Can anyone give me any tips? It would be a shame to toss thing thing out.

Thanks!

 

[tommyp]

Problem solved. I have one less eprom ecu in my ecu junkpile now. There ended up being a few traces that looked OK but were apparently open. If anyone cares, the problem was the feed to +v pin #5 of IC109. Lesson learned, if a trace looks like it's good, do not trust it. Buzz it out.