Thunderbolt - on mark 4

[Formula sr1]

Darn thunderbolt Headaches
So the season comes to an end and so does one of my engins as far as spark goes... Went to drop it in for a last run and no start ! Gas is there but no spark from the coil ! Wire at coil reads about 10 volt but battery shows 12.4 ??? Replaced the sender in the distributor and the coil itself and zero spark still... But again does show 10 volt with ignition on ... Does the coil need to read 12 or above too to Mean the thunderbolt to get going or ??? Wonder where to go from here - do I try and figure why the wire only gets 10 volt or just forget that and move on from that ? Would it run with only 10 volt I wonder ? If so I will move on to the nxt possibilities ?
If it was the kill switch , would the engin still turn over or just a dead key like it was in gear kinda deal ? I'm at a standstill - no idea where to go from here

 

[Don S]

Re: Thunderbolt - on mark 4

What are we working on, engine type and year would help, and a serial number if you have it.

 

[dingdongs]

Re: Thunderbolt - on mark 4

did you get the three wired sender and if so the black cable has to be earthed against a good known ground.did you do the green/wire spark test or are you just throwing parts at the ignition.

 

[Formula sr1]

Re: Thunderbolt - on mark 4

89 ...454 mark IV , yeah i put a new sender type with the black wire (and grounded it right on the block) And also added a new coil... Still same prob, zero spark leaving the coil ? But what I find strange is I read barely 10 volts at the coil with ignition on while the other engin reads 12.3 volts at the coil matching the battery's ? Checked and cleaned wires as much as I could... Wire from the thunderbolt also reads 10 volt (not 12.3 like the battery's). So I don't know if it's my problem or ??

 

[dingdongs]

Re: Thunderbolt - on mark 4

have you checked the shift interupt switch as this may be shorting your ignition.

 

[Fishin Magician]

Re: Thunderbolt - on mark 4

thunderbolt......go directly to the points for lack of spark...check HV wires for resistance..forget volts ..look for ohms and resistance
just saying...had same problem
FM

 

[dingdongs]

Re: Thunderbolt - on mark 4

check this out ; http://forums.iboats.com/showthread.php?t=578443
do you have voltage on the red/white wire entering the distributor?????????

 

[Formula sr1]

Re: Thunderbolt - on mark 4

Well - after bypassing the kill switches, swapping the thunderbolt units ... Still zero spark coming out of the coil ! Turns out all it was - bad ground on the thunderbolt !! Bypassed the ground that attached to the bolt on the exhaust - put a solid ground wire to the engin block and now getting enough spark to light up the moon