4.3 Mercruiser ignition question

[usemorenukes]

Hello everyone!

I've been browsing the forums as a ghost but decided to post. I have a 94 bayliner capri that i'm in the process of fixing up and i've got a possible ignition amp problem (turns over, doesn't sputter or cough)

I followed the following flow chart (http://www.justanswer.com/boat/2fbma-4-3-mercruiser-no-spark-test-procedure.html) and its pointing to the ignition amp and I have two questions.


1) Has anyone had this issue before with this model?
2) Does anyone know the correct part number for the ignition amp?


Thanks in advance, could really use any tips you can offer.

 

[achris]

Re: 4.3 Mercruiser ignition question

Hello usemorenukes, and welcome.

First things first... What is the serial number of the engine? The 4.3 litre engine has been used by Mercruiser since about 1983, and it has many variants now. Without knowing exactly which one you have we are just guessing in the dark about the problem.
Secondly, have you identifier the ignition system as a Thunderbolt IV system?

To answer your questions as directly as possible.
1. With so many of these out there, I'm sure SOMEBODY has had one die.
2. no serial number, can't look it up for you....

Chris.........

 

[Don S]

Re: 4.3 Mercruiser ignition question

I have a 94 bayliner capri that i'm in the process of fixing up and i've got a possible ignition amp problem (turns over, doesn't sputter or cough)

Sounds like you have no spark, being a 94 you should have the Thunderbolt IV ignition. Here is the troubleshooting chart for that system.

 

[usemorenukes]

Re: 4.3 Mercruiser ignition question

Hello usemorenukes, and welcome.

First things first... What is the serial number of the engine? The 4.3 litre engine has been used by Mercruiser since about 1983, and it has many variants now. Without knowing exactly which one you have we are just guessing in the dark about the problem.
Secondly, have you identifier the ignition system as a Thunderbolt IV system?

To answer your questions as directly as possible.
1. With so many of these out there, I'm sure SOMEBODY has had one die.
2. no serial number, can't look it up for you....

Chris.........

Thanks Chris and Don,

Chris, I will have to check, where is the s\n located?

Don, I have used that flowchart and its pointing to the ignition amp. The guy I bought it from said it was running on the lake fine then it died he "assumed" it was the fuel pump but it isnt.


Thanks,

 

[usemorenukes]

Re: 4.3 Mercruiser ignition question

Thanks Chris and Don,

Chris, I will have to check, where is the s\n located?

Don, I have used that flowchart and its pointing to the ignition amp. The guy I bought it from said it was running on the lake fine then it died he "assumed" it was the fuel pump but it isnt.


Thanks,

*Correction*

Don, your flowchart is different from mine, I'll check it out tonight. Thanks,

 

[usemorenukes]

Re: 4.3 Mercruiser ignition question

Im having a little confusion with this section of the flowchart.



The bullet connector (female ) distributer side WHITE/RED wire shows .3x volts with the key on.

The other side (male) WHITE/RED shows 9.xx volts.

Also, where is the serial number located? I removed the ignition module and it says Thunderbolt IV and has 3E20A V6-14 written on it.

thx

 

[achris]

Re: 4.3 Mercruiser ignition question

It will be a zero, followed by a letter, then 6 numbers...

 

[usemorenukes]

Re: 4.3 Mercruiser ignition question

is there an easy way to see the serial number? would it be on the rear of the starter ? thx

also, can you tell me which side of the white/red wire the diagram is referring to in each section?

 

[daydreamer1252]

Re: 4.3 Mercruiser ignition question

usemorenukes.....while not an expert in these things your reply confuses me....when I read the instructions I don't see any instruction to disconnect the white/red bullet connector.....UNLESS you get a 0v condition at the white/red terminal on the distributor....they ask for the voltage present at that point....if the connector was plugged in and you got the voltages your report on either side of the connector then the connector itself is HIGHLY RESISTIVE and is likely the source or your issue.....I would suggest plugging the connector TOGETHER and take that measurement and use that as your reference....if you get 1-12 volts then continue on and forget the part of the tree to the LEFT at that point as it DOES NOT APPLY......just sayin'

 

[Don S]

Re: 4.3 Mercruiser ignition question

How are you doing the tests? With your Volt meter, the black test lead must go to a good ground, not the - terminal of the coil or some other wire, or measuring between the two plugs when you unplugged the wire.
Black to ground, then the red test lead checks the voltage.
You also have to have the battery charged to do the tests.

 

[Don S]

Re: 4.3 Mercruiser ignition question

I edited the flow chart to put numbers on it so it would make it easier to ask questions.

 

[usemorenukes]

Re: 4.3 Mercruiser ignition question

I edited the flow chart to put numbers on it so it would make it easier to ask questions.

Thanks Don, I'm going to pick up a spark gap tester tonight just incase the troubleshooing takes me that way. I will post the results later tonight.

 

[daydreamer1252]

Re: 4.3 Mercruiser ignition question

Don...I am only observing but if I were to read the chart as it now is I would START by 1) REPLACING the ignition module and then 2) REPLACE the wiring harness then 4) REPLACE the ignition sensor.......I'm sure that is not what you are meaning...are you??.....just sayin'

 

[Don S]

Re: 4.3 Mercruiser ignition question

Maybe I need to redo those numbers. I can see how it could be confusing. The numbers weren't meant to be the starting point, just to put a number on each step so if someone has a problem they could say something like "I don't understand step 8"


EDIT: Cured that problem, put it back with out the numbers.

 

[Don S]

Re: 4.3 Mercruiser ignition question

Let's try this numbering system on for size and see if it's less confusing.

 

[daydreamer1252]

Re: 4.3 Mercruiser ignition question

Don, thanks, even I could follow that with no problems....now if I only had a boat NEW enough to have a TB IV I'd really have something....really strange that Mercruiser didn't number it originally.....thanks again Don for all you do for the forum and for each and every one of us who come here.....

 

[Don S]

Re: 4.3 Mercruiser ignition question

The OEM manuals are not designed nor intended for DIYers. They were intended for Merc dealers and the techs that go to the schools and take the training. Even as hard to use as the manuals are for DIYers to use, they are still a thousand times better than the aftermarket DIY manuals that leave out all the important stuff.

 

[usemorenukes]

Re: 4.3 Mercruiser ignition question

Not sure what changed but I let the battery charge over night and checked all the connections on the distributor, sprayed a little carb cleaner in the carb and she started right up. Maybe it a litter corrosion or the battery wasn't charged fulled. I opened a new thread regarding fuel pump questions. Thanks gentlemen!