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Discussion Starter · #1 ·
I have been through the ringer on this one. As stated in another post, I just bought my
first vette in 15 years, 91 vert, 49K miles really nice condition, stock L98. I only had the car for 2 days put about 250 miles on it no real problems, slight rough idle at a stop. Then it died. It would start up and run for a second then die. The car has only been driven about 3K in the past 4 years so it sat a lot.

I caved in and took it to a GM dealer, I not have a relatioonship with a good mechanic or shop yet and, I just do not have time to do the work right now. Anyway, they diagnosed a bad PCM and claimed shorted injectors were the problem. I decided to take it home since thay wanted 1700 to do the FIs and another 450 to do the PCM. I figure if that is the true issue, and I was going to replace the FIs anyway this winter, I might as well do this myself for around 1000 bucks and a lot of swearing.

I got the FSM and I have a “newbie” question regarding how to interpret the instructions in the FSM. I am just going to take my time on this but I also do not want to cause other damage to the car by trying to learn how to work on it. The electrical part of this process is what scares me the most.

I have been through the fuel supply diags and all tested good. The TBS and MAP are ok, fuel pressure is great and holds, return line is clear. I am diagnosing the starting problem and I am looking at Chart A-3B Engine Cranks but won’t run (6E3-A-24).

At steps 6 & 7.

#6 says to probe injector harness terminals with test light. Does this mean to test the purple/white wires at each injector? I assume I would ground my test light and poke each wire to see if the light comes on the test light? I should see 12V on both the purple and the white wire at each injector?

#7 If I put the noid light back into an injector plug, and disconnect the distributer 4-way, it says to momentarily touch the the harness connector circuit (430) with the test light to 12V. I am really not sure how t interpret this statement. Does this mean to apply 12 volts to the end of the harness where it plugs into the ECM circuit 430? Any suggestions on the best way to do this?

Sorry if this seems like a no-brainer question to many of you, I just want to make sure I do not toast something in the electical system, ECM while diagnosing this issue. Thanks to any and all of you who have any advice.
 

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i dont use a test light if i dont have to,first they are a dead short and ecms dont like that,second not too many people can tell the diff of 9 volts or 13 volts with a test light,use a GOOD dvom meter.if the noid is blinking when cranking the ecm is doing its job,you can ohm each injector to look for a short. small tip GM systems shut off fuel if it detects no spark
 

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Discussion Starter · #3 ·
#6 says to probe injector harness terminals with test light. Does this mean to test the purple/white wires at each injector? I assume I would ground my test light and poke each wire to see if the light comes on the test light? I should see 12V on both the purple and the white wire at each injector?

I have a meter so that is not a problem, but specifically, I should just put the meter leads on either side of the injector boot (plug) and read the voltage? This would show me the total voltage, but how can I check each wire? should both the purple and white wire have 12v? I thought one of them should not carry any voltage all the time?


#7 If I put the noid light back into an injector plug, and disconnect the distributer 4-way, it says to momentarily touch the the harness connector circuit (430) with the test light to 12V. I am really not sure how to interpret this statement. Does this mean to apply 12 volts to the end of the harness where it plugs into the ECM circuit 430? Any suggestions on the best way to do this?

specifically, how do you interpret the statement "touch the the harness connector circuit (430) with the test light to 12V." I am not really sure what I should physically do? apply 12v to something? what specifically is the harness connector circuit? I understand that on the ECM I have a plug for the 430 (purple/white) should I unplug it from the ECM an apply 12V to it to see if it lights the noid? The FSM further states "touch the terminal only momentarily and note injector light" This implies to me that I should be toughing the ECM "terminal", but that makes no sense. DOes this mean to touch the end of the "terminal" of the harness that plugs into the ECM?

Sorry if I seem obtuse about this, I jsut need a little push to get me started and then I think I can ride on 2 wheels.

Thanks
 
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