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ATCAT, GM Master Tech
Category: Chevy
Satisfied Customers: 16
Experience:  GM Master Tech/ GM Diesel Tech/ ASE Master Tech
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1993 Chevy Astro: Firing../>Situation: 1993 Chevy Astro Van Engine

Resolved Question:

1993 Chevy Astro Not Firing

I did ask this before but could not pick up the answer please reply again.
1993 Chevy Astro Van Engine suddenly died at intersection.
(Engine has a total of 120000 miles).
It Is not Firing, No Spark.
I took the following steps to fix it.
I replaced coil with new one.
I had Ignition module tested at Auto-zone, it tested good.
I have 12.33 volts coming in to coil with ignition on.
Also 12.33 volts coming in to Ignition module.
Tested pick up coil at connector it has 864 ohms resistance. Which should be good according to my repair manual.
Also exchanged distributor cap, and rotor and spark-plug wires.
Spark-plugs where exchanged 3 month ago.
And still there is no spark at all.
Submitted: 9 years ago.
Category: Chevy
Expert:  ATCAT replied 9 years ago.

The most common faults causing a no spark condition on the 4.3L engine are faulty ignition coil wire, moisture inside the distributor cap or faulty ignition coil. It sounds like you have already covered these bases. Other things to consider are the ignition module and pick up coil wich you have already tested. The ohm reading for the pick up coil sounds good to me, however I am not a big fan of electrical parts from or electrical parts testing at Auto-zone. For know lets trust that the ignition module is ok. The next component you should suspect is the crankshaft position sensor (CKP). Make sure it is pluged in and that the wires are not damaged. It should be in the timing chain cover near the bottom of the ballancer. I do not have the ohm spec for testing it at home but it should generate an alternating current whenever the engine is spinning that increases with rpm. If your repair manual does then by all means test it. When I get to work tomorrow morning I'll see if I can find an ohm test for it. I live in the pacific northwest and you should hear from me around my 10 AM break.

Customer: replied 9 years ago.
Thank you for the respond,
I followed your instruction, the wiring around the coil seems to be ok.
I am located in Arizona Desert and it is bone try here, so moisture is not too much of an Issue.
I tried to locate the crankshaft position sensor behind or around the balancing wheel, but I can not find any sensor or wiring in the area of the balancing wheel.
Staying in front of the car and looking inside the motor compartment. There is a sensor on the top left side of the engine block, but it looks more like the water temperature sensor. Pleas tell me where I am going wrong.
Expert:  ATCAT replied 9 years ago.

I may have made a mistake by having you look for the crankshaft sensor. I forgot that in 93 there are two types of 4.3L engines one has fuel injectors on top of the throttle body that you can see inside the air cleaner, there will be two electrical connectors, and the other does not. Wich one do you have?

Customer: replied 9 years ago.
Took Air filter housing off, inside I can see two what looks like connectors on left and right side which are wired.
Expert:  ATCAT replied 9 years ago.

Ok this is throttle body injection If you dont mind I would like to start from the beginning, when checking for spark I like to use an old spark plug, remove the coil wire from the distributor install spk plug and set it on intake manifold so I dont zap myself then crank engine I also like to lift off air cleaner so I can see if the injectors are squirting fuel this way you can see if you have spark and fuel delivery at the same time. If a spark plug is not available you can pull the back the boot an the end of the wire and do the same as with the spk plug but the wire wust be close ground like 1/8 in or so.

Customer: replied 9 years ago.
Checking for spark:
I do not get any spark on the cable coming from coil going through distributor. I even took the risk to get zapped by holding bare wire.
Checking fuel delivery at injectors:
I can not really see the injectors, but I can hear them and it smells like gasoline.
Anyway if there is a problem with the fuel delivery, would it interfere with the firing?
Expert:  ATCAT replied 9 years ago.

The reason I asked about fuel injectors is that the signal from the pick up coil is necessary for the fuel injectors to operate. I am 99.9% sure that you have a faulty ignition control module. You have 10 or more volts at terminal "C" and "+" . You have tach signal because the injectors are operating. The only thing left is a faulty Ignition control module. The only way to know for sure is to get one and install it. I bet it starts right up.

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Customer: replied 9 years ago.
You are Good!
I went back to Auto zone and had them test the module again. In 6 test it failed 3 times.
Don't know why the module tested good in the very first test.
So I purchased a new module installed it, and engine started right away.
How do I get in touch with you in case I have future problems with the chevy astro?
Since I am using this service first time I want to make sure you get your money. I guess I just click on the Accept Button ??? Let me know.
And Thank you again you made my day, many blessings to you!
Expert:  ATCAT replied 9 years ago.

Glad that I was able to help solve your problem, and yes clicking the Accept Button is all you have to do. Sometimes when a module fails it still sends the correct signal but the signal is very weak. This weak signal is picked-up by the test equipment and the module passes the test, however this weak signal is not strong enough to trigger its companion component in this case the ignition coil. I think that you can access my profile from the main page and request that I answer any questions. Keep in mind though that my fellow experts are also good and can help you as well as I. Thank You, atcat