1989 4.3 tbi recently restored for the most part. Had some issues a little while ago where it was running like a top and then it wasn't. The symptoms through me for a loop but after a couple days of working on it I checked the ignition control module and it was the culprit. After replacing that it ran great for about a week and then it didn't again! Naturally I replaced the control module since its a warranty and still nothing. I have a spark from coil to distributer and from distributer to plug,injectors are working properly and poured fuel directly in the carb and still wont fire off. It'll turn all day but thats as far as it goes. I also cant get the ECU to flash a code so naturally im extremely aggravated. After all that I've pretty much narrowed it down to a couple of different things. Im leaning toward the pick up coil but have never replaced one so im hoping for some feedback before I dive in. Would a faulty pick up coil have the same symptoms as a ignition control module? Any feedback is greatly appreciated.

 

The pick up coil is what sends a pulse to the ECM. The ECM sends a modified pulse with the correct ignition timing to the ignition module. The ignition module sends the pulse to the ignition coil. The ECM also uses this pulse to fire the injectors. So, if the injectors are firing when cranking, the pick up coil is good. There has been a problem with the tiny wires on the pick up coil breaking inside the insulation. Looking at the wire, it appears fine. Wiggle it, and it might just come apart. This can also cause an intermittent condition when the vacuum advance moves the breaker plate inside the distributor.

 

Have you pulled the plugs and made sure they are not fouled? Also take a look at the TPS voltage. Should be around .5V with throttle closed. Pull the IAC (idle air control) to make sure it's clean. What shape is the spray pattern out of the injectors?
TBI is simple stuff and I really like it. As long as you follow the air, spark, fuel triangle there is very little that can go wrong sensor wise.

 

The wires,plugs and distributer are all brand new. The injectors are working great,nice cone shape delivery. Even poured gas into the intake and it still wouldn't fire. When my ignition control module went out initially I w as still getting fuel and fire. Thats why it threw me for a loop because I was always told that a faulty control module would kill the injectors and the spark and I had both on ignition. I noticed when I unplugged the ignition control module Sunday that the two prong harness from coil to the module had split in half,basically the metal conectors had separated from the plastic harnes on one side but it was still connected. The Tps seems fine when I checked it and I can't see where a bad tps would cut off a vehicle and not crank back. Basically after all my tests it either one of three things,MAP sensor,Computer or pick up coil. In the past both ecm failure and map sensor trouble have always flashed codes,and this time it wont. Which is what is leading me to the pick up coil.