thunderbolt electrial problem. HELP!!!

BigBK

Petty Officer 3rd Class
Joined
Jun 23, 2009
Messages
95
have a 1987 5.7 with the tunderbolt ignition system. was hard to start this year and when it did could not get it to idle. only down to 1000 rpms. knocked off, now wont start at all. changed cap, rotor, and new sensor but still have no sparke at the plugs or coming out of the dist. any other thing to check? also have 12 on the neg side of the coil with the key on. HELP
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: thunderbolt electrial problem. HELP!!!

TB4troubleshooting.png
 

BigBK

Petty Officer 3rd Class
Joined
Jun 23, 2009
Messages
95
Re: thunderbolt electrial problem. HELP!!!

Thank You, i have gone thru this list. got it from here. have done all but replace the ignition module. have had severl people tell me thet the module almost never goes bad. so that is why i have not replaced it and the other reason is the cost of it. before i spend $350.00 on this part. i was hopeing i could get a good answer or guess as to if this could be the last pos problem
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: thunderbolt electrial problem. HELP!!!

If you actually followed and did all the tests from above, especially step 1 below (from the previous reply) and we know you have changed the coil, then #3 seems to be your only oprion.

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Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,344
Re: thunderbolt electrial problem. HELP!!!

remove the Green/white from the shift interupt switch
remove tach feed , gray wire on neg side of dist.
 

BigBK

Petty Officer 3rd Class
Joined
Jun 23, 2009
Messages
95
Re: thunderbolt electrial problem. HELP!!!

ok , have done all those things, last was the tach wire and still no fire. LOL i guess its the last resort. so much for (they almost never go bad). one last question with the key in on position should you have 12 volts on the neg side of the coil? im not sure
 
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