Fingers crossed it is the plug. Good luck.
From the wiring diagram it looks like you can get sparks even without any ECM. It looks like the ECM is driven by a signal from the module, and not the module from the ECM.
I have actually done that - as an experiment on a different vehicle - the ECM was disconnected completely but I still got sparks.
The power to the module shows to be coming from the ignition direct to the distributer. Part of the module deals with sensing the distributer position, and triggering the spark. The other part tells the ECM it is time to play and open the injectors.

 

Weird things do happen with cars, what I have writen is the diagnostic routine that I would follow if I were to look at your vehicle based on the info you have given so far. I believe the purple and white wire ( all the info I have given you is from memory ) feeds the ECM. Run a continuity test from the modual connector to the ECM if you think the wire is the problem. I've never had a car with spark that didn't have injector pulse and the modual was the problem ever and I have done gross amounts of problems like this. But hey what matters here is you get your car fixed.. Anyway.. if you can, print what I have given you and follow it in the order it is writen and see if it helps.. Good Luck

P.S. don't forget about the TPS voltage. The computer will not fire the injectors if it thinks the engines flooded. However most of the time the engine will continue to run after you start it with carb clean or whatever...

 

i had a similar problem with my ta. had spark and fuel but wouldnt start. turns out it was the mas! didnt read the whole thread so i dont know if this helps or not. good luck.

 

if the signal that fires the injectors comes from the pickup and theres no voltage reducer between the signal and the injectors then slice the signal wire to the tach wire...........

he he he he...... they both are getting the signal from the pickup coil.... remember, if it has a voltage reducer you can't use it....

 

UPDATE!!!

I checked the injector wiring harness with a test light with the key turned on. The light came on at both sides.

I also checked the 4-wire plug to the back of the dist with the key turned on and nothing at all 4 wires.

Now what do you guys think???

 

Was that with the injectors inpluged ? unplug them all just to be sure... Then if there is power on both sides.. unplug the computer. If it only powers on one side of the injector harness with the computer unpluged then replace the computer besure that you followed what I had writen earlier. If it still has power to both sides with the computer unpluged regardless, you have a short to power on the ecm injector control wire.

 

Yeah, I checked them with ithe injectors unpluged. I will unplug the computer and check this week end.

What about the 4-wire plug. It showed nothing. Should this be right. no volts going to the module?

I wish someone would check the wiring harness to there dist and let me know if it has any volts to it with the key on.

 

I don't think there is any voltage on the connector coming out of the back of the distributor until the engine is cranking.

 

Here are the instructions from the 83 model book to check the problem. It can't be too different on yours.
You need to get to plug 'B' on the 4 wire connector from the distributer. this is known as circuit 430. It is a single purple and white wire that goes to terminal 2 on the computer. I think this is tab 'R' on the module.

You need it to be connected up though, i.e., still going to the ECU.
You need the ignition on and the engine cranking.

When cranking, measure the voltage between 'B' and ground. There are three conditions to look for:

2 volts and above, the module is faulty.

1 to 2 volts and varying, the connector at the ECM or distributer is faulty, maybe loose or corroded.

under 1 volt check the wire from 'B' to the ECM looking for either a open circuit or a short to ground.

For info. connection 'D' is ground, 'A' is from the knock sensing EST circuiit, 'C' is the bypass.

However you mentioned earlier about the engine running when you put gas into the inlets. This indicates that the connection to the EST is ok, otherwise if I read the book right you would not get any sparks, which I ddn't know before.

You did mention also that after cranking a while, the fuel pressure dropped off. In the 83, if the ECU does not get a reference signal from the distributer after 2 seconds of cranking, it shuts off the fuel pump, until the engine either fires or the cranking is stopped.

It really does sound like either the reference wire is broken internally or shorted out or the connector for plug 'B' is not making the circuit. Did it get stretched? You say it ran then would not start the next day, the wire could have been stretched and the last run up and engine vibration finished it off.

You should be able to check if the signal wire to the ECM is open circuit or shorted with a restance meter.

 

Any luck yet?

 

Didnt get to work on it this week end. Hopefully one day this week. If I cant find the poblem soon, Im going carb.

oh yeah. the motor and computer is a 92, I do know that the dist changed later on during production, so I dont know if the 83 book would be the same or not.

 

Have been following your post. For what it's worth I had a similar problem and after replacing the ECM, Ign Mod, Coolant sensor, MAF relays, Fuel pump relays, Knock sensor and O2 sensor still nothing. Checked voltage at Fuel pump relay with ign off and had 12V with ign on but not cranking voltage dropped to about 6V. Eventually decided to remove entire engine wiring harness. It was a pain getting it clear at the back of the engine but eventually got it out. Found that the insulation where the 12V wires from ECM were spliced to the wires from the fuel pump / oil switch / maf relays was nothing more than dust and wires were barely connected. Couple of other wires were in bad shape including one of the ground wires from the ecm. Also previous owner had done some mods and wires were poorly connected - instead of a good splice had just wrapped some insulation tape around the wires which were beginning to fall apart. Had intended to replace entire harness but ended up cutting out the damaged wiring and replacing with new - checked all other wires visually and for continuity. Put it all back together and engine started first time. It is running a little rough but this is most probably the ecm getting used to all the new sensors. Most probably could have saved a few bucks by not replacing the sensors but as some of them have been in some time it did not do much harm. I also noticed that when I removed the ignition mod the piece of plastic that insulates the two connectors was completely wasted and connections from pick up coil corroded - could not get a replacement from a store but found one at junk yard.
Not sure if this is your problem but I certainly feel better having cleaned up the wiring - looked like it was a fire waiting to happen. I have attached a picture of the wiring after I removed it - hope this does not deter you.

 

andrew, I am hoping that wiring is my problem. You know the 4-pin connector to the dist. I am going to replace it. and hopefully it will fix the problem.

Yeah, it is a big job to remove the whole harness. I did it when I changed from TBI to TPI. It wasnt too bad, just had to take my time.

Hopefully, I wont have to go to the extreme like you did, but I will be replacing the black wire loom for blue so I could check the wires then.

Did you reset your computer after changing all your sensors? could even be a leaking vac line for your rough idle.

 

I know this may sound completely retarded but I was working on my fathers 82 custom S10, has a 305TPI motor in it , had the same EXACT problem. Turned out it was out of gas... we worked on it for 3 hours and finally realized it was out of gas(20gallon s10 tank, put 2 gallon in, wasn't enough).

Just a thought. Anything could help at this point.



Brendan

 

yep, 1/2 tank. Thanks for trying though and welcome to the board.

 

Whoops, I forgot to log out of my second account. Something is bugged on the classified section and my regular account won't log in properly so I made a second one for just classified use

Wish I could help on the problem... hard to say..

 

wow... i have never seen this much help... this is y i love all u guys.... i dunno maybe... did u check the battery itself... i dunno if anyone else sugested that.... i dunno, thought i would try to help...

 

yep, checked the battery. its fine and I have a charger on it also.

Thanks for the input. I am going to try to work on it tonight and try a few things.

 

Have you done any valve lash adjustments lately?

I have over-tightened the valve lash before and it leaves the valves open at all times - very little to no compression.
All my car did was turn over and over.
Took me 3 days before I did a compression test.
I felt like such a dumbass . . .

 

Hey.. I was wrong on the injector power supply. I use noid lights which are a small bulb that Plugs into the injector plug and flashes as the injector would fire. Just went out to my bird and checked the plug and both sides for pwer... They were both indeed hot with the key on.

Only a few things will cause this problem. No injector pulse =
A. Continuity problem from purple white wire to ECM ( Means that you need to measure the ohm reading from the distributor wire purple/White to the ECM ) Should be about the same as if you touched the two leads together on the meter.

B. Have you checked the TPS voltage and for codes ? Clear flood is a real mode of the ECM and will disable the injectors if the TPS voltage is at it's upper limits.

C. Bad ECM

Good luck...

 

poppa chubby, I havent touched the valves, but glad to know that can happen.

90formula-x-f, I have cleared the codes many times, and the tps is set at the suggested volts fro a SD system, I think 0.57 not for sure, but when I set it, It was right on the money

Its starting to get dark here early, so I guess its time to break out the flash lights. By the time I get home from work, its already dark, and the car is under the carport not in a garage sad to say. So I having to work on it when I can, so sorry for no updates.

I will let you all know what I find as soon as I can get to work on it somemore. I really want to get her up an going to get some track times in before they shut the track down.

thanks

 

UPDATE!!!!!!

I did some work on the camaro last night. I replaced the 4-wire plug going to the dist. Man was it twisted when I got it out and was looking at it. The plug it self was just twisted up and across in two or three directions. So I dont think it was seating in the module properly.

I put the afpr back on, checked the plugs on the dist cap to make sure they were in order "I took them off to change the 4-wire connector". I am going to get some intake gaskets and put the plenum back on, re-check all the fuses, charge the battery, check fuel pressure, check all vaccum line, and clear all codes.

I hope this works. Everyone keep thier fingers crossed. I will let you guys know how it turns out.

later
bluegrassz

 

ITS RUNNING!!! ITS RUNNING!!! :lala: :lala: :lala:

:hail: THANK G-O-D!!! ITS RUNNING.

I was the 4-wire connector. After I cut it out and replaced it. It fired right up. The plastic connector was very badly twisted, but I couldnt tell how bad untill I took it off.

man does it feel good to get her going again. I did however have to adjust the idle screw on the tb. When I started it up, It would only Idle about 400 rpm. I had to keep on the gas to keep it running. Then I popped the cover off the idle screw and adjusted it. I am going to barrow a timing light tonight and set the timing.


Thanks for everyones help!!! I appreciate all the advice everyone has given me. thanks again.

bluegrassz

P.s. hopefully I can get some motor pics now.

 

when u get thoes pics! post'em ASAP i wana see ur set up

 

No poblem. It may be a few days before I can, but I will as soon a possible.

 

That is ace. Brilliant.

 

My car ma have the same problem but I did not take anything apart yet. I dont hear my Fuel Pump kick on when i turn key to on. It Cranks and Cranks. If the fuel pump is bad then starter fluid in the TB will make it start then right? Or bad Injectors???I dont know PLX HELP ME

 

Yeah, try some starter fluid in the TB. But you should get a fuel pressure gauge to check and see if you are getting any pressure.

Also check the fuel pump fuse.

 

I have a similar problem. Right now, I am not getting neither spark nor fuel dumping down the shoots, but the engine does crank over. I have checked all the fuses and they are good. I've read the whole thread and from what I understand, the ign. module controls both spark and fuel? Obviously spark, but fuel as well because it sends a pulse to the computer, which in turn sends signal to the injectors. Am I getting this right????
BTW, this is for a 305TBI

 

Im not yellin at ya, but this is better anwerd at the TBI section.

 

I hate to say it, but I just got fed up and went carb.

But it would be a wise idea to have your module checked. Have you checked your fuel pressure?

 

91NitRida

First of all, this section is for TPI related posts. There is a board to ask TBI question on.

Second, WTF did you ressurect a post that was over a year old for? Nothing wrong with doing a search for answers, but if you don't FIND the answer in your search, you're likely not going to get it by resurrecting the first post that was never fully answered.