4.3LX Thunderbolt IV missing after engine rebuild

[4.3mudder]

I have a picture on my phone of the flow chart. And have gone through it a few times. At the end of this I'm pretty sure it's the module.

 

[4.3mudder]

Oh man I'm sorry to hear that. I have done a lot of readings by him and he was good.

 

[achris]

Oh man I'm sorry to hear that. I have done a lot of readings by him and he was good.

No, he was not good, he was brilliant. We all miss him, and not just for his vast knowledge base....

Now, testing the module. Unless you're willing to pull the distributor out, and set it up on a bench with a voltmeter and an oscilloscope, (as I have) then the flow chart is the only real way to confirm whether the module needs replacing or not. The other way is substitution. If you have a friend with a 4.3, then that would be worth a try.

Chris.....

 

[4.3mudder]

I got a good volt meter but I do not have an oscilloscope. I didn't even know what that was until I google an image and thought whoa I for sure don't have one or know anyone who does. Is there anything else I can use in its place? And yes the post I have read from him have been awesome. Straight to the point and knew exactly what he was talking about.

 

[4.3mudder]

For the hell of it. I even disconnected everything from the coil. Ran a wire straight from the battery to pos side bypassing everything. And still the same thing. Is the could itself that's in that band need to be grounded?

 

[achris]

Ok, here's a quick way to test, if you have a spare coil, lead and spark plug. (and a 555 timer chip kicking around)

Pull the module out. Set it up with the coil and a 12 volt line coming in. I would set up a 555 timer with a 50% duty cycle so I could adjust the 'revs'. Have the white/green wire from the module go to the 5 volt point of a voltage divider. The output pin of the 555 being the 12v source for the divider network. Use a pot on the 555 and run the 'speed' up and down. This will confirm the module, or not.

Chris....

 

[4.3mudder]

What is a 555 timer?

 

[achris]

An IC (integrated circuit/'chip') designed to have a couple of resistors and a capacitor connected so it will turn on and off. You can configure it as a 'one-shot' or as a 'clock', just going on/off/on/off as long as you like. Changing the resistor and capacitor values with change the timing, using a potentiometer in place of one of the resistors will make the frequency adjustable.

for more info... -> https://www.google.com.au/search?q=...hannel=sb&gfe_rd=cr&ei=n2ARVIOsA8KN8QeS2oDIDA

Chris........

 

[bfjou812]

While I don't know what an ignition module cost for this ,you might try this. Check for a speed shop or a high
performance engine shop in your area and see if they can check the distributor on a machine. I used to have mine set up by a local speed shop when I was racing. It might be worth it. Just my 2 cents ........

 

[achris]

You would need to take the distributor, complete with module (which in this case is screwed to the side of the dissy), coil and a wiring diagram, and advance curve. Let me know if you need them and I can post.

Chris.....

 

[4.3mudder]

Well. I got the kit put in this evening. No instructions but have done prior research and was able to wire everything up using deutsch connectors. Few spins and was purring like a kitten. Timing was done with the shunt. Runs great. So. The module must have been bad. Just funny why 3 weeks of sitting up because of engine rebuild and it goes bad. But all in all. I'm glad it happened in the shop at home versus on the water somewhere. Do appreciate all your guys input. Now that I got the distributor out I'm gonna find someone with an oscilloscope and verify for the hell of it.

 

[4.3mudder]

I think that timing curve is in the service manual I got from mercruiser

 

[4.3mudder]

I think I may have gotten confused on the timing. I install the shunt. Black wire to 12 volts. 650 rpm and 8degrees btdc. Since I have no instructions. Achris I know you know.

 

[achris]

I think I may have gotten confused on the timing. I install the shunt. Black wire to 12 volts. 650 rpm and 8degrees btdc. Since I have no instructions. Achris I know you know.

What distributor/module did you put in?

... Now that I got the distributor out I'm gonna find someone with an oscilloscope and verify for the hell of it.

Unscrew the module off the distributor and mail it to me. I'll do a report for you. PM and I'll give you my address...

 

[4.3mudder]

I installed the 481058 AC Delco kit. I started the engine, installed the shunt, connected the wire to 12v on the battery, and set timing to 8 BTDC.

I can say thing. I bought this boat used and it ran fine and even bought a couple props for it. Now that I have this new ignition system in it its as if I did an engine swap from a V6 to a V8. I have to get all different props now because all are under propped now.

 

[4.3mudder]

Not sure if it was the actual engine rebuild, carb rebuild, or this new ignition system, but something made it run better than new.

 

[NHGuy]

all the above!