dudeman66

Hey guys,

I know this is a really common problem but everyone seems to have different problems occuring causing this NO pulse situation. So my question is.. how do you manually pulse the injectors to test them? I have heard of people doing this in the past. My setup is a 1986 camaro 305.

I have spark and i have fuel pressure. I have also heard that the pickup coil can cause these problems but if the pickup coil was bad would I still have spark? Or the igniton control module. So the pickup coil or ICM is what signals the injector to pulse? Just seems to me that if one of these were bad there would be no spark. Also should I be able to see the fuel spray from the injector? cause I have the fuel rail upside down on the intake so i can see if they spray.

People also say to check the injector grounds as they go to the ECM. Sure they do go to the ECM but what do I check? The grounds coming out of the ECM? ALL my grounds are hooked up.

Heres another issue. My distributor is the small remote coil style. I thought this coil was only on 87' and newer TPI cars? It couldnt have been swaped because the harness has the 4 prong connector for the distributor. IS this more than likely an 87 harness?

thanx guys

vetteoz

iTrader: (13)

That they are open and not to ground with the key off. If wires are to ground anywhere then the ECM can't ground them to control injectors
Should have 12V on other side of injector plug with key on

dudeman66

OK so heres what I did, With the injectors all plugged in and the key off, i checked one injector plug from both sides and the ohms meter didnt pick anything up so I assume the wires are not grounded. So thats good right? Unless I did it wrong but I had one probe in the injector plug and the other probe on the engine block.

Next thing I checked for was a 12v supply at the injectors.. If all the injectors are Unpluged, I do have 12v to one side of the plug. It should have been the pink wire side correct? But If I plug just one injector in (say on the left bank).. I have 12v at both sides of the injector plug and also on both right and left bank injectors. So this makes some scence becaue the injector is not an on/off switch cause its got constant resistance of 12.6 so I assume its feeding that 12v right through and over to the next plug and so on. But what I dont understand is why if I plug just one injector in on the left side that it would feed power over to the right bank. Cause thats all it takes, If i plug just one single injector plug in, I have 12v to both left and right banks on both sides of the plug. ??????

If all this sounds OK i'll move onto the next thing. Checked the pickup coil, It reads 841 ohms. If I trun the dist by hand the voltage output of the coil is 0.4 and if I turn it with a drill it puts out 1.9 volts. Its safe to say that the PU coil is probably ok.

Oh yeah and also, i checked all my injectors... they all read about 12.6 ohms and they are LT1 injectors, or so I was told. But I also have a set of TPI injectors and they all read 16.6 ohms.

thanx guys

vetteoz

iTrader: (13)

So everything you tested is fine

What is your TPS set at ?
Too high a voltage while cranking and ECM will shut down the injectors

dudeman66

Hmm not sure, will go check. what if the TPS is not plugged in? Will it not start? Cause I could just unplug it and try that.

Heres another thought. Being that I took all this stuff right out of a camaro, and put it on an old truck.. do I need to do something about the VAT system?

vetteoz

iTrader: (13)

Already asked you about that on the other site

read
http://www.corvettebuyers.com/c4vettes/l98.htm

gczj13

so was this ever fixed and what was the problem

bird6750

I wasnt getting any injector pulse and intermittent spark. Replaced the starter, ICM, coil, pick up coil, cap/rotor, fixed Vats and still no injector pulse with noid light. Replaced the distributor with reman unit from Auto Zone and it fired right up. A bad dizzy can cause a no pulse or intermittent pulse to injectors. Good luck to all!

djmarch

iTrader: (4)

I guess I'll try your route next. I too have the same issue. Checked all grounds on the heads, (even cleaned them). Checked the ground wires to the ECM...All good...Even by passed VATS with a chip. I have good fuel pressure at the rail, spark on #1 plug wire, but no start. I'm really at a lost here on what to troubleshoot next.

gczj13

Well I replaced the distributor at it made no difference. I think my issue came down to the prom but I never got around to replacing it

rgarcia63

Let's just look at one injector because all the injectors are connected the same regardless of which fuse bank they're powered from.
With the Ignition Switch in the Key On/Eng Off position there should be 12vdc on both wires of the connector, but in the run position and the depending on the precision of your volt meter the 12vdc may not be steady as the ECM is switching the 12vdc on and off.
To see the pulses from the ECM you need a Noid light plugged into the connector, it will blink if the 12vdc is being switched to ground by the ECM.
The noid light is used to test the ECM not the injector.
An 18 ohm injector will most like be intermittent, or not open at all, the higher the resistance the less current it draws once it falls below .8 amps it will not open properly.
With the ECM pulse signal, injector resistance, and fuel pressure checked and all within spec you should have at least one injector flowing fuel.

Just expanded what VetteOz said in a few simply words.

-RJG