ENGINE NOT STARTING...KICKING MY BUT

[prc03sx195]

I have an 03 I/O mercruiser 4.3 and just tried starting after sitting 3 wks. Checked fuel at carb inlet and it is getting it from pump. Checked coil for voltage and it is getting 12 v on purple wire a ign coil. Checked for continuity at ign coil and it is not open so I figured that could be ok. Pulled plug and laid it against ground surface to check for spark while cranking and there is none (is this a good check)?
What else can I check and where do I go from here? This is killing me. Thanks for the help.

 

[Rick Stephens]

Need fuel and need spark to run.

No spark means you have a bad connection or a failed part. To get good answers you should probably post serial number and type of ignition.

 

[Scott Danforth]

Do you have the original 2 wire ignition module or the updated 3 wire?

 

[prc03sx195]

How can I tell if I have two wire or three wire? I'm pretty sure it is the original equip since I owned it from 06 and on.

 

[Scott Danforth]

You pull the dizzy cap, then pull the rotor and look

 

[prc03sx195]

ok I can do that but the last time I tried to remove the distributor cap I could not get it off, it seemed like it was sealed on the housing. So what will this tell me and how does it influence the trouble shooting? What am I going to knowing if its 2 or 3 wires?
I don't have a wiring diagram so are there any lockouts or devices that would cause the ignition to not function?
Thanks for the help.

 

[Scott Danforth]

If its 2 wires, most likely it failed and you need a new ICM.

 

[prc03sx195]

It is a 2 wire. Can the boat dealership test these module's? Or do they just buy it and hope for the best? How can I be sure if they can't be tested, these are not cheap items?

 

[nola mike]

Is this a tb-5?

How Mercruiser Thunderbolt ignition systems work.

Mercruiser Thunderbolt ignition systems. Mercruiser introduced the Thunderbolt IV onto their engines in 1982, alongside the introduction of the 1-R drives. The TB-IV system was used until the introduction of TB-V mid-way through 1996. Thunderbolt V was an improvement on an already exceptionally...

forums.iboats.com

 

[prc03sx195]

I am not sure what a tb-5 is? The engine S/N is M323847 and the model is MCM 4.3 L. It is a 2 barrel carb with 2 wires coming out the dist. Thank you

 

[nola mike]

Thunderbolt 5 ignition. Looks like you have an MPI engine, which is a different beast than the standalone systems... But you say you have a traditional coil?

 

[prc03sx195]

It has a traditional ignition coil and it also has an ignition module or amplifier. The engine model is MCM whatever that means.

 

[prc03sx195]

Ok, just saw that I have a tb-5 ignition. So now that I know that where do I go from here. Thanks

 

[poconojoe]

I have a 2003 4.3

I was able to pin point the problem by going through the TB-5 troubleshooting chart.

If it's the ignition module under the distributor cap, it's not expensive. I paid $46 for a Mallory unit 3 years ago.

The hardest part for me was getting the rotor off. Apparently they are glued on from the factory. I had to cut the rotor in pieces to get it off while being careful not to damage the shaft.

The ignition module was pretty easy. The old one on mine was a corroded exposed circuit board. It had two wires. The ground connection was through one of the mounting screws.
The new one was a sealed unit with a third wire which was the ground. I grounded that wire to the block.

While I was at it, I changed out the cap, rotor, wires and plugs. Nothing like a good tune-up.

 

[prc03sx195]

Can you send me the trouble shooting guide? Thanks

 

[nola mike]

I linked it above...
Strange though, when I plug in your sn I'm getting an MPI engine. Is yours original?

 

[Rick Stephens]

If you are going to keep this boat more than a week or two you might consider purchasing the manuals for it.They will surely keep you on track.

One place is here: http://outdriveshop.com/mercruisermanuals.html

Or you can get form dealers.

 

[prc03sx195]

I brought this boat 3-4yrs old. Nothing has been done since I owned it. The s/n could be off in the 3rd digit, it's rubbed off partially. Does that change my diagnostic work on the ignition system? Thanks for the help.

 

[nola mike]

I brought this boat 3-4yrs old. Nothing has been done since I owned it. The s/n could be off in the 3rd digit, it's rubbed off partially. Does that change my diagnostic work on the ignition system? Thanks for the help.

Yes, follow the tb troubleshooting guide above...

 

[San_Diego_SeaRay]

Here's a useful flow chart from achris' explanation of the TB Ignition system: