From Steve Woods
www.vortexbuicks.com site.
Assuming the battery is charged, the car has compression, and the fuel pressure is adequate, If you have:
1. no spark, but have injector pulse - Check the Ignition Module (also check the CCCI and ECM-IGN fuses)
2. have spark, but don't have injector pulse - Check the Cam Sensor or ECM
3. have no spark or injector pulse - Check the Crank sensor or the Ignition Module (and fuses)
If the car does not start, establish the information required to pin the problem area down to one of the three guidelines listed above.
1. Connect your volt meter to the battery and try to start the engine. Read the voltage on the meter. It should be above 10.0 volts or the car will not start as the ECM will not get enough voltage to operate. It is important to to crank the engine with the starter to put a load on the battery as a battery with a bad cell may read good when there is no load on it, but it can easily drop three volts when the starter is engaged.
2. Check the fuel pressure. It should be up around 40 psi. If it is down in the 20's, it may not be enough to start the engine and you will need to find out why the pressure is low.
3. Is the Check Engine light illuminated when the key is turned to ON? Check the
ECM-IGN fuse, the
ECM-SOL fuse, and the
CCCI fuse. The No Check Engine light trouble tree does not mention the ECM-SOL fuse but I blew one and lost the check engine light and the car shut off. I don't see why when looking at the diagrams but it cost me an expensive wrecker ride to figure this one out.
Here is the chart for No Check Engine light. It is a simple process; use it!
4. Does the ignition have spark? Pull a plug out, put the appropriate wire back on it and lay the plug on the valve cover or hold it to a good ground. Crank the engine over with the starter. Do you see a good blue spark across the gap? To avoid any fluke of nature, pull each plug wire off and check it for spark on one side of the engine (this will verify that all three coil packs and the module are working).
5. Pull the fuel injector harness off an injector (mash in on the spring clip on the bottom of the connector and lift the connector off the injector). Plug your Noid light into the connector. Crank the engine. Does the light blink steadily while cranking? (this verifies that the injectors are receiving injector pulses from the ECM and the crank and cam sensors are working) If you don't have a Noid Light, go buy one! A single noid light costs between $7.00 and $13.00 depending on where you buy it. They make different noid lights for different injectors. Be sure you buy the one that is labeled
G.M. PFI or G.M. PFI-B. If the Noid light does not blink while cranking the engine, then you do not have injector pulse! Don't try to use a volt meter because you don't see the need for the noid light. The injector will only be getting power for less than 0.002 second. Neither your meter nor your eye is faster enough.
Now, using the information gathered above, you should have a good idea which of the three guidelines above applies and pin the problem area down. Problems with the crank sensor is often obvious if the bracket that mounts the sensor has broken. If not, then check the sensor for proper clearance to all three blades on the back of the damper.
The cam sensor is easy to check if you have a Caspers Cam sensor. Just plug it in and rotate the engine to see if the light on the tool goes on and off. If you don't have it, the trouble tree will tell you how to check for the rise and fall of voltage as you rotate the engine.
The ignition module is hard to check and it is usually easier to swap out than rely on a parts store tester that probably does not work on our modules anyway. None of the aftermarket modules that are offered in parts stores other than the Standard brand module will reliably work in our cars. I cannot say the Standard module will work every time but it has worked for some. None of them will work with the Caspers Coil Tester which only works with the original module. ACDelco #19260720 Ignition Module is offered as a replacement. I don't have any experience with this unit but it apparently works (not with the tester). I would not be surprised to find it was made by Standard but I am guessing.
The best replacement is the TR 6 sold by Bailey Engineering. It costs twice as much but it works as well, if not better, than the original and offers several additional features.
No real way to test the ECM other than to swap it out. It's a good idea to buy one off Ebay or elsewhere to have as a spare.
