Good afternoon, Ive been lurking around here for a while using this site to fix little things here and there, and now I need some real help. Im having a little trouble and I think I pinned it down, but need a little reassurance and maybe some tips form the knowledgeable ones here. Lets start with the vehicle: '84 2m4 with 2.5. with 4 speed unmolested as far as I can tell. Now the problem. I was merging onto the expressway and she died. just died. all electronics worked except engine. After pulling on to the shoulder, I discovered my fuel pump wasn't coming on. the fuse was good, swapped just in case. still no fuel pump. That pump was old and loud so I figured it was time for it to go. SO I replaced it with a 88 2.5 fuel pump (previous owner hack job) all is good with fuel pump. No start still. She cranks fine. -no fuel from fuel injector, bone dry -fuel pump is running as it should as is described in so many threads. -I checked flow to filter both inlet and outlet. all good. Got the good pressurized mist when cracked used my redneck ways to catch gas and had a buddy turn pump on to check for flow...all good. -checked for flow at the throttle body on the injector side, good there as well. -checked for pulse with a noid light, no pulse whilst cranking -checked for spark, no spark -ohm'd distributor pickup, within tolerances -checked continuity of distributor wires, all ok - I did take the ICM to autozone for testing. they put it through 10 consecutive test and it passed everytime. Then checked the CEL code in diagnostic mode.......only code was 12.....weird might be worthy of noting that my tach was acting wonky the day before. Like it would hang in no certain parttern or point, just random. And also that the tach shows no rpm while cranking. She ran beautifully before this. Could it be my ECM has thrown in the towel?
Any suggestions or questions? please and thankyou.
-Sincerely Shiz
[This message has been edited by shiznizbiz (edited 04-10-2014).]
Welcome to the Forum! Your ECM has not completely quit on you if you are getting a code 12. When you crank the starter does the Tachometer move up to about 300 rpm? IF it does not, you should test your Ignition Control Module.
The ECM fires the injectors based on the ignition pulses it receives. So if the ignition system isn't putting out anything then the ECM won't fire the injectors.
No raising tach when cranking = bad primary ignition system
Flaky tach before failure tends to indicate ignition problems.
So do you have +12v (use a 12v test light) on the pink wire to the coil?
[This message has been edited by phonedawgz (edited 04-10-2014).]
Im so sorry, I left that out. I did take the ICM to autozone for testing. they put it through 10 consecutive test and it passed everytime. It got really hot too. the guy burned himself. but it passed. Ill edit my o.p. to reflect that. thanks though.
Are you referring to the primary winding of the coil itself? The ignition coil is only a month old, but I never rule anything out due to mr. murphy. I didn't check that though. does that effect the fuel delivery as well as the spark?
quote
Originally posted by phonedawgz:
The ECM fires the injectors based on the ignition pulses it receives. So if the ignition system isn't putting out anything then the ECM won't fire the injectors.
No raising tach when cranking = bad primary ignition system
Flaky tach before failure tends to indicate ignition problems.
So do you have +12v (use a 12v test light) on the pink wire to the coil?
Im so sorry, I left that out. I did take the ICM to autozone for testing. they put it through 10 consecutive test and it passed everytime. It got really hot too. the guy burned himself. but it passed. Ill edit my o.p. to reflect that. thanks though.
OK, it works at Autozone..... did you put it back in your car and does the tach go up when you crank the starter?
The primary ignition components are the power wire into the coil, the primary side of the coil (1/2 of the coil), the wire between the coil and the ICM, the ICM, the pick up coil and the rotating magnets inside the distributor.
One more double check - does the distributor turn while cranking the engine? A bad cam gear would mean the dist stops turning and thus the ignition system would not put out any pulses.
If you do have power to the pink wire on the coil with the key on, then make sure both plugs are on the coil and see if you have power on the pink wire at the ICM connector.
The coil bridges the two pink wires - the one supplying power from the engine harness - and the second pink wire that runs to the ICM
[This message has been edited by phonedawgz (edited 04-10-2014).]
Ok, just ran out to test -No needle raise when cranking. -12v test light shows power to pink wire going to coil but not to the icm -distributer turns while cranking.
Next?
[This message has been edited by shiznizbiz (edited 04-10-2014).]
-12v test light shows power to pink wire going to coil but not to the icm
No power to the ICM = no spark. Why isn't the power flowing through the simple connector on the coil and thus reaching the ICM? The power is just bridged between the two pink wires by the coil's connector.
[This message has been edited by phonedawgz (edited 04-10-2014).]
Back up please... First thing is pull oil fill cap and watch rockers movement when someone else starts the engine. No moving then no spark or fuel and means cam gear strip off teeth.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
Back up please... First thing is pull oil fill cap and watch rockers movement when someone else starts the engine. No moving then no spark or fuel and means cam gear strip off teeth.
yes ogre, the rockers are still rocking. just checked.
I'm a bit confused on the failure of the coil test and the failure of the passing of the 12v to the ICM.
Either of these will prevent spark. Most likely only one has failed. The wire on the ICM - COIL cable closest to the pink wire on the COIL - Engine harness cable will be the one that passes the +12v to the ICM.
Second - when you are reading the coil in test B what reading are you getting? Does the needle move at all?
edited, false info. I had a bad ground with my test light on those last test for the icm to igniton coil connections....those are good. there. that straightens those out. but it doesn't effect that my coil still failed the test described in the diagram
[This message has been edited by shiznizbiz (edited 04-10-2014).]
The coil will produce no spark. The lack of voltage from the open windings will produce no tach signal.
excellent, thanks. Sorry for the confusion earlier. Now for the for the no pulse signal to the fuel injector. Would this bad ignition coil cause no pulse to the fuel injector?
The ECM fires the injectors based on the ignition pulses it receives. So if the ignition system isn't putting out anything then the ECM won't fire the injectors.
No raising tach when cranking = bad primary ignition system
Flaky tach before failure tends to indicate ignition problems.
So do you have +12v (use a 12v test light) on the pink wire to the coil?
good afternoon. well, I replaced the ignition coil. She runs now. my tach is still wonky though. it still hangs randomly Thanks for all your help Gall757, phonedawgz, and ogre.
