93 5.7 merc no start ignition problem thunderbolt IV bravo drive

[stang32]

i replaced the sensor, wires, cap & rotor, swapped out a coil and it is acting the same way it was prior. the engine cranks and kicks back intermittently, tries to fire and on the rare occasion, will start and die within 5 seconds. it is not what i usually run across, thats why i am bringing it to the forum. i have not run the diagnostic chart yet but will be, next time i go to the boat. this has the module mounted on the distributor. i hope its not the module but base on the symptoms, and that ive never run into this scenario and i have never condemmed a module, i can safely assume it will turn out to be a bad module. any thughts?

 

[stang32]

is the distributor mounted module the same part # as the manifold mounted

i am trying to find out if they interchange and the manifiold mounted will plug into the dist mounted

 

[Scott Danforth]

What are you working on?

 

[stang32]

93 5.7 lx/ bravo set up serial # 0f008032

 

[achris]

History of TB modules are in here...

http://forums.iboats.com/forum/engi...-mercruiser-thunderbolt-ignition-systems-work

 

[achris]

What happened prior to the problems starting up? (any work done on the engine, like a dissy pulled and put back in 180 out?)

Have you run a compression test?

Chris.......

Edit: 2 threads appear to be about the same problem. I have merged them.

 

[stang32]

no, the boat was fine, but my buddy called me in when the impeller whiped out and the boat started smoking. he shut it down (allegedly) right away. i helped him put a new pump assy on and it would not start. the starter sounded like crap, like it needed shimms but i knew that wasnt going to help it. we replaced the starter and when trying to crank it, the engine would kick back some times. i checked the flywheel and thankfully it does not seem to have any chipped teeth. there is definelty compression but i havent run any testing . all signs for me point to it being an ignition problem, it is just so hard to condem a module that is that expensive without complete confidence.iwill be runnign the diagnostic tree later this week. the plugs when removed do not show any water in intrusion so i dont think it overheated too bad, if at all

 

[achris]

It was overheated and by the sound of it, quite badly, but nothing happened to the engine... :noidea:

I doubt your problems are the ignition system... Start with a compression test. I bet it'll show a blown head gasket....

Chris.......

 

[stang32]

trust me, it has no spark.

 

[stang32]

i still have the question, is the module the same if it is installed on the exhaust riser as the one installed on the distributor?

 

[greno]

the engine cranks and kicks back intermittently, tries to fire and on the rare occasion, will start and die within 5 seconds.

How is this "no spark"?
A badly overheated engine can blow a head gasket. As suggested, you should do a compression test.

 

[stang32]

looking for alternatives to $650.00 thunderbolt IV ignition module

i need to replace the module on my TB ignition system. the module is 805361t3 but it is NLA and the replacements are over 600. bucks. anyone go another route? i considered swapping out the entire distributor/igniton set up for an aftermarket this is for a 93 5.7 bravo set up

 

[stang32]

this is no spark because i am getting no spark. at 1st it was intermittent and now, i get no spark at all. after testing it , i ran the trouble chart and it comes up with a bad module. also i said earlier when it ran, it ran smooth for the amunt of time it was running. maybe it was more than 5 seconds but it was short lived.

 

[greno]

This is the same issue as your other thread.
Why start an entire new thread? Go post in the thread you already started.

 

[greno]

How do you get from an impeller going out causing the engine to badly overheat to thinking that your ignition module is the problem?
Help me understand.

 

[stang32]

regardless if it has a bad head gasket or not, it has no spark, you tell me how a blown head gasket will cause a no spark condition?

 

[greno]

Ok, let's work through the issue.
You have a "no start" condition.
How did you determine there is no spark?

 

[stang32]

This is the same issue as your other thread.
Why start an entire new thread? Go post in the thread you already started.

what are you talking about?
i posted about needing t replace the module and trying to find an alternative to the 600 dollar one from merc.
the question is specific .

 

[greno]

The mods didn't think so. It's part of the same discussion about your "no start" condition.

 

[greno]

Again, how did you determine that you had no spark? Just because the engine doesn't run doesn't mean you have no spark.