so i have a problem with not getting ground to my fuel injector from the ECM. anyone have clues to why?? as soon as i manually add ground, the injector turns on. but its too much gas going to the tbi. by the way i have the 84 duke.

[This message has been edited by hyphynator1984 (edited 03-22-2012).]

Stop shorting the injector to ground right now. Ok, lets test some things. Try this.
Does the SES light come on. Can you pull any codes?
Unplug your TPS. Work now? No, plug it back in
Test your fuseable links. There are some in the same area as the battery and some next to the starter. If those test good go wash your hands for the next step
Get in your car and remove the ECM cover. Put a test light on the orange wires of the white connector going into the ECM. You should have power to both orange wires.
.......

i will try all the steps and ill let you know.

No ignition or ECM thinks No ignition = No Injector signal

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Let’s clarify something, unless the engine is cranking over there won’t be a ground to the injector. The injector has power all the time when the key is hot and the ECM sends a “pulsating” ground signal that varies in frequency depending on how much fuel the ECM wants the engine to have. Be careful when testing this. For example, if you use a test light that draws too much current it will damage the ECM.

so the injector does work if i manually add ground to the blue wire. im just not getting the “pulsating” ground signal from the ecm. i switched the ecm twice. imma go to the junk and try to get another ecm tomorrow and ill give an update. and i did follow that same diagram to check if all the wires are correct and they are. just added the new fuel pump, new fuel filter, new but used tbi, new injector, cleaned the fuel tank, and replace the fuel relay.

the main issue is that the blue wire from the fuel injector in not getting the “pulsating” ground signal

You need to troubleshoot your ECM, not replace it.

1 - Key on engine off - Does your SES (Service Engine Soon) light come on? It should

2 - Key on - does your fuel pump run for two seconds and turn off? It should

3 - If you just bump the starter, does the fuel pump turn on again, and then turn off two seconds later? It should. Note - This test is meaningless if you crank the engine more than a bump. The fuel pump will also get turned on by the oil pressure switch and cranking a cold engine will turn on the oil pressure switch quickly

4 - Does your tach rise to 200 rpm during cranking and then drop to 0 after? It should.

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Tests 1 and 2 indicate your ECM is getting power and at least that portion of the ECM is working.

Test 3 indicates your ECM is getting ignition pulses from the ignitions system. If the ECM does not get ignition pulses then the ECM does not think the engine is turning over and thus will not pulse the injector.

Test 4 gives you an indication if your primary ignition system is working. If the tach worked before but now is not raising to 200 rpm during cranking, most likely your problem is actually an ignition system problem. Again the ECM won't pulse the injector if it doesn't see ignition pulses. Did you check for spark?

[This message has been edited by phonedawgz (edited 03-23-2012).]

Very well said (phonedawgz). Also, don’t supply a constant ground to the fuel injector. It’s not designed for full voltage constantly and it can get damaged. Unfortunately the damaged injector can also damage the ECM.

what problem are you trying to solve exactly?

No pulses to the injector is a major symptom of a failed ignition module or pickup coil. It CAN be the ECM, but if your check engine light works, its not nearly as likely as the ignition module or pickup coil. like phonedawgz said.

Injectors are Grounded by the ECM to fire them. They are supplied 12V power whenever the key is on.

The Ignition module feeds the engines reference pulses directly to the ECM, telling it to fire the injectors.

iwill try this as soon as i get back from the junk this morning. thanks for the info

quote Originally posted by Fierobsessed: No pulses to the injector is a major symptom of a failed ignition module or pickup coil. It CAN be the ECM, but if your check engine light works, its not nearly as likely as the ignition module or pickup coil. like phonedawgz said. Injectors are Grounded by the ECM to fire them. They are supplied 12V power whenever the key is on. The Ignition module feeds the engines reference pulses directly to the ECM, telling it to fire the injectors.

I've been using this conversation to fix my 84 iron duke also. I found the problem but I need some info to fix it. I took the ICM out of the distributor and there's this little red plastic box beside the ECM with one wire screwed to the inside base of the distributor (ground) and the other wire (burnt off) goes back into the harness. What is this little red plastic box, resistor? New ebay distributors don't look like they have them.

Welcome to the Forum!

Did you mean to say ECM, or is that a typo?

I'm not sure. I thought the ECM was the computer under the center. I'm referring to what I believe to be called the ICM, ignition control module under the distributor cap. Maybe I got my wires crossed. Pardon the pun. Lol

So where is the little red plastic box?

Sorry. This little red plastic "chip"(might be a better way to describe it) is inside the distributor next to the ICM. With one wire grounded, and the other leading back into the harness.

Does it look like this?



If so it is the tach filter. It's job is to block the tach from killing the ignition if the tach were to fail. How to test? Unplug the tach filter and see if the problem goes away. What will unplugging the tach filter do? All it will do is disconnect the tach from the ignition system. So it will only disable the tach.

No it's just a little red chip inside the distributor. I think I managed to properly wire in an 86 distributor. It doesn't have one of those in it. Tried to fire it up today only to find out the cam gear is stripped. I managed to get the gear off with the motor in, and I'm going to pick up a gear tomorrow. Wish me luck.