2005 Mercruiser 5.0 thunderbolt V ignition has no sparks

[lost_boys]

Hello,
Boat stop working over Memorial weekend and finally got some time to look why there were no sparks at the spark plugs.

Tested for spark at the ignition coil and there was no spark...removed ignition coil and retested with just a battery and manually toggle the 12V to the coil. No sparks with that method either...
Got new Ignition coil and cant get spark using just a battery and gap tester. Am I doing it right or you can't use this method to test a mercury ignition coil...

Attached a pic of my setup

===minus of coil to NEG of battery
=== switch from positive of coil to POS of battery
===bypassed ignition cable and attached gap tester directly to coil
=== ground other side of the gap tester
=== just meter to make sure everything is making contact

=== then I just toggle the switch to connect the 12V and I should see sparks but I dont

any thoughts to my setup, am I doing this correctly and the new ignition coil is bad also...please help

 

[achris]

You will only get a spark when you DISCONNECT the 12v, not connect it. It's the collapsing of the magnetic field generated by current flowing that causes a high voltage to be induced in the coil primary, which gets stepped up in the secondary...

And you need to disconnect the NEGATIVE, not the positive. (think 'points')

Chris.

 

[lost_boys]

That makes sense, since most of the how to videos were connecting and disconnect the GND side...I did that also, but still no sparks...

Connect "coil plus" to POS of Battery and than manually toggle the "coil gnd" to the NEG of the battery....I still dont see sparks....do you think they ignition coil has been damaged???

 

[Scott06]

This shows how to trouble shoot the system https://forums.iboats.com/threads/how-mercruiser-thunderbolt-ignition-systems-work.676476/

should be able to ohm the coil .6-.8 ohms on primary side, 9400-11700 ohm on secondary side

 

[lost_boys]

This shows how to trouble shoot the system https://forums.iboats.com/threads/how-mercruiser-thunderbolt-ignition-systems-work.676476/

should be able to ohm the coil .6-.8 ohms on primary side, 9400-11700 ohm on secondary side

thank you so much, this will give me more info while I wait for the new ignition coil.

I did measure the resistance of the coils to verify all my connections were good at the start of testing. The new coil has more resistance compared to the original which is inline to what u stated. I just dont want to waste couple of days while I wait for another coil and then find out it was a user error where I dont get a spark...

 

[lost_boys]

thank you so much, this will give me more info while I wait for the new ignition coil.

I did measure the resistance of the coils to verify all my connections were good at the start of testing. The new coil has more resistance compared to the original which is inline to what u stated. I just dont want to waste couple of days while I wait for another coil and then find out it was a user error where I dont get a spark...

too bad I can't produce a spark from the ignition coil manually...I'm ready to follow the flow chart to isolate the issue....looks like there are only 3 parts that could be the issue if all the wiring is OK...the sensor, module and coil itself

 

[Scott06]

looks like there are only 3 parts that could be the issue

the sensor, module and coil itself

would add a fourth if you are getting spark off coil itself cap and rotor could be a problem area. Can loose spark there

 

[lost_boys]

would add a fourth if you are getting spark off coil itself cap and rotor could be a problem area. Can loose spark there

how true, but I would be so excited just to get sparks right now ...

on a different note, do you have to remove the distributor cap to replace the ignition sensor....still researching for potential problems

 

[lost_boys]

how true, but I would be so excited just to get sparks right now ...

on a different note, do you have to remove the distributor cap to replace the ignition sensor....still researching for potential problems

disregard the question...looks like I have to remove the distributor cap but dont have to mess with all the other stuff underneath to get to the sensor

 

[achris]

disregard the question...looks like I have to remove the distributor cap but dont have to mess with all the other stuff underneath to get to the sensor

2 terminal or 3 wire sensor?

 

[lost_boys]

2 terminal or 3 wire sensor?

I watched wrong video so I'm not sure what I saw So I dont know how to install yet

sensor looks like 3 wire- red/white, grn/white and a black

 

[lost_boys]

I watched wrong video so I'm not sure what I saw So I dont know how to install yet

sensor looks like 3 wire- red/white, grn/white and a black

found parts daigram, not too complicated to replace the sensor

 

[achris]

3 wire sensors are very reliable. And 'video'? I didn't do a video on the ignition system, it was a thread, explaining all the different parts and how it all works.

 

[dubs283]

3 wire sensors are very reliable.

Only the oem 3 wire sensors are reliable. Aftermarket = no good

My WAG, as usual with a t bolt no spark, is the ignition sensor. Have replaced more of that component than coils and modules combined by far

OP, you must follow the troubleshooting guide mentioned in this thread. Find it in the stickies at the top of the forum page. So much information has been given to you in this thread that you can sort out step by step by simply following the guide. FYI, you can manually get the system to spark, if you follow the guide....

 

[lost_boys]

Only the oem 3 wire sensors are reliable. Aftermarket = no good

My WAG, as usual with a t bolt no spark, is the ignition sensor. Have replaced more of that component than coils and modules combined by far

OP, you must follow the troubleshooting guide mentioned in this thread. Find it in the stickies at the top of the forum page. So much information has been given to you in this thread that you can sort out step by step by simply following the guide. FYI, you can manually get the system to spark, if you follow the guide....

thanks all, I have gone over the flowchart how to debug the ignition several times. great stuff...

What I wanting to know if my setup to throw spark using a 12V battery and toggling the Battery GND to the Minus of ignition coil is correct...if so, then the new ignition coil is bad also and I will wait until another arrives tomorrow...

I hate to wait and find out my test is incorrect and I did the test wrong...If I have a known good ignition coil, I can start debugging using the flowchart to isolate the issue to the module or sensor

Since there hasnt been much comments on the setup other than I need to toggle the GND, I assume my setup is OK and I should be able to throw sparks on this mercruiser ignition coil

 

[achris]

If I was setting up a test bench like that, I'd get as close to a points set up as I could. That would include a ballast resistor in the positive side and a capacitor (condenser) across the switch you're using to stimulate the points.... I'd then use a known good coil to confirm the test rig works...

Chris....

 

[lost_boys]

If I was setting up a test bench like that, I'd get as close to a points set up as I could. That would include a ballast resistor in the positive side and a capacitor (condenser) across the switch you're using to stimulate the points.... I'd then use a known good coil to confirm the test rig works...

Chris....

thanks, that seems complicated...I'm leaning towards just putting the coil back into the boat and use the flowchart to see if I can throw a spark...thanks

 

[achris]

thanks, that seems complicated...I'm leaning towards just putting the coil back into the boat and use the flowchart to see if I can throw a spark...thanks

That's what I'd do. For every million coils replaced, only about 3 are actually faulty.

 

[Scott06]

thanks, that seems complicated...I'm leaning towards just putting the coil back into the boat and use the flowchart to see if I can throw a spark...thanks

Did you ohm test the coil ? if it passes the ohm test it is good... or just reinstall it and go through the trouble shooting

 

[lost_boys]

sorry to complicate my issue with a bench test...anyhoo, followed yalls recommendation to put back into boat and follow flowchart

got 12V coming out of the module, then rapidly strike the GRN/White wire from module to GND, got sparks out of the ignition coil...YEAAAAAA

Looks like the issue is with the sensor, reconnect the GRN/white wire and turn the engine on, no sparks