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No Spark - Ignition Module?

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ignisuti

Member
I have a 1995 Rinker Flotilla with 4.3L Mercrusier engine. It has a Thunderbolt IV Ignition System.

It ran great last winter when I put it away. Now today, I tried to start it on ear-muffs. If just barely started to fire-up, but died. I got it do the same one more time and then never again... Now, it only cranks. I verified gas is going to the cylinders. I then used a screw-driver to complete the connection between the coil and the distributor, but I do not see a spark. I assumed ignition coil and replaced that. When that didn't work, I did a bit more research and troubleshooting. Here's what I found.

-Ignition Coil has +12V on positive terminal (with key ON), but only if I put negative multimeter lead on and actual ground. Is the negative terminal of the ignition coil supposed to be grounded? I do NOT get a reading when I use that terminal as my ground.

-I found a Thunderbolt IV troubleshooting diagram and followed it through to the step that says check for 1-12V on the "WHT/RED terminal on distributor". I'm confused here because there are two WHT/RED wires going to my distributor. One goes into the bottom and the other goes into a module mounted on the distributor via a large 4-pin connector. Also, it did not say to test with Key ON, but that only makes sense to me...? The 1st wire showed no voltage with Key ON and Key OFF. The 2nd wire showed +12V, but only with Key ON.

Question: Is "ignition module" same thing as "ignition amplifier"?

Note: My fuel pump runs constantly with Key ON and I also have an Alarm with Key ON. I honestly don't remember if these issue were present when I put the boat away last winter as the boat is still fairly new to me and I'm still getting familiar with it. I'm troubleshooting these as separate issues, but if anyone thinks they might be related (that would be awesome), please let me know.
 
Update:
I bought an online manual and realized that the 2 WHT/RED wires are the SAME wire!! It just twisted back to where it was hard to see. I realize I posted some conflicting info in my last post, so I went back to re-test. I found that with the WHT/RED wire disconnected, there is 0V coming from the Ignition Module. According to the Test instructions in my manual, it says to replace the Ignition Module. I also found that my grey tach sender wire is grounded. I traced that down to ALSO be caused by the Ignition Module.

So, I'm going to try and replace that part next.
 
You need to slow down.

I have attached two images.

1, coil resistance check, (basic but gives a starting point and may not be exact for every coil) NOTE: Coil - is NOT ground it is the negative side of coil only

2. TB V ignition test flow diagram. Same as TB IV

step 1- disconnect grey wire from coil -. This is tachometer lead from tachometer. If tachometer is bad it can short coil to ground
Remove coil wire from center terminal of distributor and connect spark gap checker, one end of spark checker goes to engine ground. (leave tachometer grey wire disconnected for remaining tests)

step 2 - Crank engine and check for spark . If NO Spark go to step 3- If spark then Tachometer is bad.

Step 3- Key in ON/RUN position-12 volts at coil + - YES go to step 4.

Step 4- Disconnect white with red stripe wire(s) from distributor and check for 12 volts on wire (this white with red stripe comes from the TIMING CONTROL MODULE typically mounted on exhaust manifold). Check for 12 volts on white with red stripe (with the key in run position). 99.9% of the time this is Yes - go to step 5

Step 5- Reconnect white with red stripe wire. Disconnect white with green stripe wire from distributor. Next remove coil wire from distributor cap center terminal and install spark gap tester.
(with key in RUN position) strike the white with green wire to ground RAPIDLY and see if a spark is created. If there is spark every time white with green stripe is struck to ground then Ignition sensor in distributor is bad and needs replacement. If NO spark then coil would be bad. With new coil and If still no spark then Timing module would be at fault (VERY VERY RARE).

Your issue may be related to your other post.........but redo tests as I described above first.

ignition_coil2.gif

ignition trouble guide.jpg
 
Wiring diagram for you engine.

Diagram on left didnt have wire colors at timing module so I added older version with wire colors

V6 wiring 1.jpg
 
Well... as mentioned in my other post, I added stereo, fish finder, and Low voltage cut-off over the winter. I feel very confident in stereo and fish find wiring. They are wired to the accessory switch power. The Low-voltage was a new electronic toy for me. So, I un-did that modification and found zero improvement.

I guess one more easy thing to test that came to me just now is ALSO unplug the stereo just incase some other wire other than power & ground landed in the wrong spot. I'll do this in a few days when the weather clears up here.

Jack, according to your Thunderbolt Troubleshooting guide, I fail at Step #1. However, it's unclear to me what to do from there. It does not say!
If I continue, I fail again on step #4 which says I need a new Ignition Module.
 
Crud! I'm not even sure how to buy an Ignition Module. I'm fairly certain I only saw 4 wires going into mine, but all the used ones I can find on ebay have 6 pins.

Any suggestions for finding a suitable replacement?
 
ignisuti said:
Crud! I'm not even sure how to buy an Ignition Module. I'm fairly certain I only saw 4 wires going into mine, but all the used ones I can find on ebay have 6 pins.

Any suggestions for finding a suitable replacement?
Click to expand...

Message me with your phone number and time zone and when I can call.

It is not the time to buy a part you may not need. The timing control module RARELY fails. Typically when it does, it will not advance timing. Less than 1% of the time will it cause NO SPARK.
 
After a few conversationswith kghost, I believe we have found the culprit. The shift shaft cable is starting to fail and bind up. This is causing my shift interrupter to not seat correctly when the boat is in neutral. And, when not seated correctly, the boat won't start.

Thanks again to kghost and everyone for all the advice as I was barking up the wrong tree!
 
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