Thunderbolt IV ignition HELP!!!!

djmakko

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I have a 87 ' 260 V8 5.7 motor with the thunderbolt IV mounted on the riser I've tried all the the tests that lead me to the amplifier being bad so I changed the distributor cap the ignition coil the ignition sensor the spark plugs the wires and a used amplifier box so everything it's new and still no spark , what's going on?? What could it be , please help before I go to the mechanic and spend thousands of dollars for something that may be simple to fix myself. Anybody??
 

Bt Doctur

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Aug 29, 2004
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19,111
Re: Thunderbolt IV ignition HELP!!!!

Bad tach? Do you have 12V at the + side of the coil? No mention of rotor.bad rotor will ground the spark.
 

Don S

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Re: Thunderbolt IV ignition HELP!!!!

a used amplifier box so everything it's new and still no spark

Maybe your "used" amplifier is bad. Go through the tests again and see what is wrong.

I've tried all the the tests that lead me to the amplifier being bad
you didn't say what thoses tests were, but here are the tests you should be going by.
 

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djmakko

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Re: Thunderbolt IV ignition HELP!!!!

First of all thanks for the replies,
Yeap I did all the test on the chart, I got 12 volt on the + side of coil after that no spark anywhere that's why I just replaced everything except the rotor , I will replace it and run the test again , of it leads me to a bad amp box I will assume this box is bad too that will be the third one , is there another way to just get rid of that box ? Different system perhaps? Can you guys recommend one ? After going tru 3 used boxes I'm thinking people sell them for a reason ( they are bad) and since there's no way to test them hard to tell
 

81 Checkmate

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1,360
Re: Thunderbolt IV ignition HELP!!!!

Yes there are many replacement system available. You will most likey have too replace the whole system. Dist,coil,and amplifier.

I have a 86 merc 260 HP also and had the same thing happen, the ignition box craped out.

I went with the mallory system with the internal ignition amp in the dist, others have went with the GM HEI replacement from Michagan Motors.

Have you tried to unhook your tach wire, could be shorting out somewere.

Just a thought. Good Luck
 

djmakko

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Re: Thunderbolt IV ignition HELP!!!!

Thanks, checkmate
I'll try disconnecting the tach wire , replace the rotor, run the test again, if doesn't start , I'm just going with the Mallory . What model you went for?
 

81 Checkmate

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Re: Thunderbolt IV ignition HELP!!!!

The part number for the Mallory is M9-26000 I got it off E-Bay from a shop in upper Ohio, 2 days and it was sitting at the door. New dist, cap, coil, and plug wirers. $365.00 + tax

It is very simular to the old style unit's but it is all electronic, + you can change weights in it for advanced curves. I had it in in less then an hour and has run flawless since. ( Nock on wood)

Hope it works out for ya
 

djmakko

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May 9, 2011
Messages
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Re: Thunderbolt IV ignition HELP!!!!

Checkmate,
i found a delco ignition system from a guy on craigslist , it came out of a same motor as mine, the guy couldn't tell me how to connect it because he had it all in pieces (the motor) he crashed the boat probably drunk lol,
anyways i did some research and found this is the delco sold by michigan motors that you suggested , now, if is not too much to ask can you lead me in to the right direction on how to install it, i know i have to make some alterations but i just don't know how
thanks in advance.
 

Don S

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Re: Thunderbolt IV ignition HELP!!!!

Hooking that up is easy. I will find the thread with the instructions and details.
 

djmakko

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Re: Thunderbolt IV ignition HELP!!!!

Thanks Don,
I'll install it this weekend and post the outcome , this is a great forum lots of info my head hurts now from reading . Got the diagram from the other post thanks again.
 

81 Checkmate

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Re: Thunderbolt IV ignition HELP!!!!

Djmakko, How did it turn out? Did ya getting running yet. Post up the results!
 

djmakko

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Messages
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Re: Thunderbolt IV ignition HELP!!!!

Ok, Heres the outcome:
I gave up!! , install the electronic ignition , distributer and coil new wires new plugs and nothing happened, although with this new distributor i got spark,but the engine was turning too slow and after a couple of tries turn a little faster, then went back to turn too slow, i figure maybe is the battery not giving enough juice so i hooked up the other battery check the both were delivering 12.6 v , crank it again nothing, i connected everything as Don say and according to the schematic he sent me , nothing , then I bypass the cut off switch , and disconnect the tach wire ,nothing i kept trying but the engine still turn slow and fart, was almost like it will go around a cycle 4 slow turns then 2 fast and then fire, then the battery was really hot and out of juice, I had gas in the carb and put a little starting fluid, nothing! check the key switch , was good , so then i thought maybe the drive was not installed correctly and its slowing down the engine , i had it replaced last year, took the drive out crank it again same thing nothing. So I just give up , I really don't know what could it be , theres no water in the oil the spark plugs were clean all the wiring seems ok, last year i had a small leak in the drive that little hole on the bottom that most of the people dont know what it is , well it was leaking a little oil never pay too much attention to it , then i went out and blowthe drive i in the middle of the chesapeake bay there was a really loud grinding noise and the engine just shut off, got towed back and got it inspected , yep it was gone, bought a used one put it in then i moved to Texas and never started the engine again until last couple of weeks and can get it to start, and i can't find any post with similarities to my case, i don't know what to do now .
 

John_S

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Jun 21, 2004
Messages
4,269
Re: Thunderbolt IV ignition HELP!!!!

Sounds like the timing is way off. Not unusual when you replace a distributer.
 

djmakko

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May 9, 2011
Messages
134
Re: Thunderbolt IV ignition HELP!!!!

i thought of that too , but the slow turning of the engine was present with the thunderbolt IV, unless when the drive broke jumped the timing chain on the engine , but from worst came good , the guy I got the distributor from its selling me the motor of his wrecked boat its 2003 5.7 350 witch looks in very good shape , mine its 24 yrs old i think it will be a good change,
 
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