injectors wont trigger from ecm ?

[Tyree]

We just wired everything with 1227747 ecm. The fuel pump relay kicks on but the injectors will not fire from the ECM. We manually pulled the injector wires to ground to be sure they were working and they were fine. They will not fire from the ecm. Does anybody know the cause of this. We triple checked the wiring schematic wire for wire and everything seems to be connected correctly. Any help would be greatly appreciated. Thanks!

[jim_in_dorris]

Simply put, the conditions that need to be met to fire the injectors are not being met. Without being in front of it to test everything, my guess is the reluctor in the distributor, but at this point it is just a guess as we don't know engine, or mods that have been done.

[mmigacz]

Are you running a stock TBI distributor? If not, what are you using? Do you know if you have spark? The pick-up coil in the distributor is needed for both spark and crank signal for running the injectors.

[Tyree]

Thank you for your replies,
This is a stock 350 engine, and 1227747 ecm from a separate vehicle from the wrecking yard. And hei distributor. We are getting spark and fuel pressure. I saw one guy on youtube attach his crank input to the tach from the distributor to c9 on the ecm. The schematic actually illustrates to attach the crank input to the starter solenoid. We tried both ways with no luck. Spent hours on it and don't want to give up. This might be a stupid question, but if the engine is out of timing, would it cause this? Thanks again to everybody on this one.

[Six_Shooter]

Ok, there's a bit of confusion on "crank input" here.

There is a "crank" signal that the ECM uses while the key is in the forward or "start" position. It is a purple/white and should have 12V on it (through a 3A fuse) while starting only. this wire can be attached to the start wire at the solenoid or the start wire at the ignition switch. Personally I use the start wire at the ignition switch, due to being away from the elements and it's generally easier to get to.

The other term for "crank wire" that I believe is being used here is actually a reference wire, or RPM signal. This will have pulses on it while the engine is turning over and running.

When you say "HEI distributer", do you mean a stand along HEI distributer, that has vacuum advance and a 4 pin module, or do you mean a distributer that has a 7 or 8 pin module and connects to the ECM? It is the later you need, in order for the ECM to know the engine is turning over to enable the injectors tow ork.

Posting some pictures of your conversion will also help greatly to better understand how you have the conversion done and we might be able to see potential sources of issues.

[mmigacz]

Sorry, my statement of saying cranking signal is confusing. RPM signal sounds better.

[Tyree]

Six Shooter, The distributor is a stand alone hei with a vacuum advance that we took off the previous carberated engine. I will get some pics posted soon. We are trying to duplicate another conversion that we watched on youtube:
http://www.youtube.com/watch?v=vqaYXrAnv84, according to this guy, he plugged his tach signal from his hei to the ecm. I don't know at this point.? Im pretty sure we tried everything. Again, we also triple checked the wiring according to the schematics. I will try to get pics posted by Tuesday. Thanks again for your help.!

[EagleMark]

C9 Purple/White wire goes to starter solenoid and gets a signal when in Key/Crank position only!

If you put it to B5 Purple/White... which I think he was trying to do it will fry the ECM without a tach filter or running an external EST...

[EagleMark]

I watched that video! The most amazing thing about it? It ran???

[lionelhutz]

Honestly, I would recommend you just get the right distributor so you can connect the distributor like it came stock. Sell the distributor you have now and get a computer controlled on or convert it to the 8-pin module the ECM needs if you just must keep the distributor you have.

[delcowizzid]

if its a reluctor style dizzy you need bosch ignition module part number BIM148 and then lock up mechanical and vacuam advance as such

[Tyree]

ok, so tomorrow we will put the original distributor back in and give it a go. I am curious to know the function of the crank input signal and what it does. If it is on momentarily when the solenoid engages the starter, is it only sending a quick 12V pulse to c9? Is this to wake up the ecm if it was in some kind of low power sleep mode while the car was off? I don't know, just trying to understand the function of this crank input pin labeled c9?

[EagleMark]

Start and choke fuel.

[delcowizzid]

the ecu's i work with only use cranking input for backfire inhibit logic so it can prevent inlet manifold backfires

[jim_in_dorris]

Just glancing at the $42 code, it uses C9 to know when it is cranking to set cranking fuel vs coolant temp among other things.