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Samstinson

Need Help! 1994 Chaparral

7 posts in this topic

I have a 1994 Chaparral 200 SL with 5.7L mercruiser engine. The engine will not start, just cranks over. I check the fuel and I’m getting fuel to the carb, but on the ignition coil with the key switched on I have power on the positive post of the coil and power on the negative post of the coil and also power on the coil wire it self. I need help please 

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When you say you have power on the negative coil post, what are you referring to? The positive coil post should show constant 12 vdc, but the negative should show to ground intermittently as engine is cranked. If it shows constant voltage, then you are reading feed power from the positive terminal through the coil winding. To prove this, remove the negative wire from the coil and check for power at the coil negative post again. I think you will find it is still there. My guess is a failed ignition module (item 6 below) in the distributor, One other item to check is the cap and rotor as the design used during that era have been found to be problematic.

http://www.marinepartsplus.com/catalog/mercruiser/serial/5.7L_2_BBL._GM_350_V-8_1988-1995/816596/1014-110

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On the ignition coil there are three points the positive post (+), the negative post (-), and the coil wire point, all three have power on them with the ignition switched on. I have not checked the negative side while cranking the engine but I will check that. There is a sensor inside the distributor and there is also a rectangular module on the back of the distributor that has a connector with six wires in it. Is that the ignition module or is the sensor inside the distributor the module? Thanks for helping.

 

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14 hours ago, Samstinson said:

On the ignition coil there are three points the positive post (+), the negative post (-), and the coil wire point, all three have power on them with the ignition switched on. I have not checked the negative side while cranking the engine but I will check that. There is a sensor inside the distributor and there is also a rectangular module on the back of the distributor that has a connector with six wires in it. Is that the ignition module or is the sensor inside the distributor the module? Thanks for helping.

 

As indicated on the attached drawing, the distributor sensor (item 6) is the more likely bad actor. It can either have a plug on connector, or the terminals with studs and nuts. It is a hall effect sender that acts as a trigger for the remote ignition module. Think of it as a digital set of points. It's optical as it looks through the open slots in the reluctor ring as the wheel spins around under the rotor. It comes off with the rotor as it is screwed to it, and you can expect the rotor to break getting the old one off, but ring is stainless and can/must be re-used. A little grease on the shaft before installation will prevent this issue in the future.  I would start with the cap and rotor as they are wear items anyway. You may have failed the remote module, but that's rare. If you send me a valid e-mail address I will send you a PDF file with test procedure but testing is a bit tedious. A digital meter will pick up voltage through the coil windings, so it does not tell you much, but testing with a simple test light connected to the negative coil post and a known good 12 VDC source during cranking will let you know if the trigger is working. 8 blinks per distributor revolution, or 4 per crankshaft revolution.  W

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On 4/12/2018 at 4:12 PM, Samstinson said:

On the ignition coil there are three points the positive post (+), the negative post (-), and the coil wire point, all three have power on them with the ignition switched on. I have not checked the negative side while cranking the engine but I will check that. There is a sensor inside the distributor and there is also a rectangular module on the back of the distributor that has a connector with six wires in it. Is that the ignition module or is the sensor inside the distributor the module? Thanks for helping.

 

That sounds like you have Thunderbolt ignition with the distributor mounted ignition module; came that way for only a few years as I recall. At any rate, on the module it should say Thunderbolt IV or Thunderbolt V.  Believe Thunderbolt V came out around 1996 and that version does require a special procedure to set base timing.

The later 892150K02 or Q02 have the integrated candy cane coloured wires without ring terminals, and has proven to be a more robust design than earlier ignition sensors.

Image result for when did mercruiser introduce thunderbolt V

Ignition sensor below is the older style that requires ring terminals. Usually one of the 2 bolts holding the ignition sensor to the distributor has a nut on the bottom with a ground cable attached. New rotor is usually required for re&re as tabs get bent.

Image result for when did mercruiser introduce thunderbolt V

Related image

 

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I replace the ignition sensor on the boat and I still have the same thing. Could it be the thunderbolt ignition module is bad? Please help

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11 hours ago, Samstinson said:

I replace the ignition sensor on the boat and I still have the same thing. Could it be the thunderbolt ignition module is bad? Please help

It's all speculation until you preform the necessary system testing. Anything can be "fixed" if you throw enough parts at if, but my offer to provide you with the OEM manual PDF file still stands. It outlines the steps required to identify the actual bad actor.  W

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