no spark on my 4.3 vortec please help

[sullified]

O.k so here it is I purchased the boat last year 1995 donzi medallian from a friend that owed me some money.The motor that was in it was a mercruiser 4.3 vortec original they monkeyed with it trying to get it running no success because it had no compressing so I pulled the motor and bought a rebuilt motor which is a 05 4.3 mercruiser.I bought a intake manifold and carb for that motor but used the ignition system from the other vortec which is the thunderbolt 4 ignition system.
O.k so here is what i have replaced so far since I have put the motor in new starter,new alt.,new ignition coil,after two got burnt up,new starter selonoid,new ignition sensor in the distributer and new cap and rotor,still no spark i have gone through the test procedures and everything is checking out even the module I have 11 volts on the white and red wire and disconnected the tac, a new ignition switch and tested the kill switch which is good. Finally to my question.I pulled the module out and everyone of those modules I have seen online the ones I've looked at have a ground coming out of the harness my does not have that but have a brass tag were the mounting bolt goes through it and which I believe grounds it to the distributor housing which is also grounded still no spark any ideas ??????
Oh ya one more thing if I still have the igniyion set up for the 05 such as the dist.and the coil and harness could I use that or would it be a whole bunch more of a pain because ive taken a few days of from working on it cause im frustrated and figured to go and work on my other project and now that has irratated me also so back on the boat lol

 

[MikDee]

Re: no spark on my 4.3 vortec please help

First, Turn on the ignition, and go to the Plus + side of the coil with an electrical tester, and see if there's voltage there, & how much? One probe of the meter on the Dist., & one probe to ground, engine manifold. Let us know what you find?

 

[alldodge]

Re: no spark on my 4.3 vortec please help

O.k so here it is I purchased the boat last year 1995 donzi medallian from a friend that owed me some money.The motor that was in it was a mercruiser 4.3 vortec original they monkeyed with it trying to get it running no success because it had no compressing so I pulled the motor and bought a rebuilt motor which is a 05 4.3 mercruiser.I bought a intake manifold and carb for that motor but used the ignition system from the other vortec which is the thunderbolt 4 ignition system.
O.k so here is what i have replaced so far since I have put the motor in new starter,new alt.,new ignition coil,after two got burnt up,new starter selonoid,new ignition sensor in the distributer and new cap and rotor,still no spark i have gone through the test procedures and everything is checking out even the module I have 11 volts on the white and red wire and disconnected the tac, a new ignition switch and tested the kill switch which is good. Finally to my question.I pulled the module out and everyone of those modules I have seen online the ones I've looked at have a ground coming out of the harness my does not have that but have a brass tag were the mounting bolt goes through it and which I believe grounds it to the distributor housing which is also grounded still no spark any ideas ??????
Oh ya one more thing if I still have the igniyion set up for the 05 such as the dist.and the coil and harness could I use that or would it be a whole bunch more of a pain because ive taken a few days of from working on it cause im frustrated and figured to go and work on my other project and now that has irratated me also so back on the boat lol

You burned up 2 coils? The TB-4 ignition uses a ballast resistor between 12V power and the coil. Only time it gets full 12V is during starting.

You should have 12V on the Wht/Red wire.



You could probably use the ignition from the 05, is it a TB-5 or something else

 

[dubs283]

Re: no spark on my 4.3 vortec please help

The TB-4 ignition uses a ballast resistor between 12V power and the coil.

no

all thunderbolt ignitions use an internally resisted coil, there should be 12 volts/battery voltage at the (+) terminal at all times

conventional (pionts) ingition systems use a ballast resistor/resistor wire between the coil and 12 volt supply not to protect the coil but to protect the points from burning up prematurely

to op:

follow the troubleshooting guide that alldodge posted, this will narrow down your search for the culprit, as far as a ground for the module, there are a few different styles merc used through the years

most grounded through a 1/4" ring terminal that a mounting bolt goes through to the exhaust manifold, post a serial # for your engine and a picture of the module to help

 

[alldodge]

Re: no spark on my 4.3 vortec please help

all thunderbolt ignitions use an internally resisted coil, there should be 12 volts/battery voltage at the (+) terminal at all times

Your correct my mistake, :facepalm: got into a non thinking mode from the op burning up 2 coils