Crank, no spark. Need advice.

[yamjer]

Hello all. Haven't been on for advice in awhile. I'm riding a 1987 Doral Citation, 350. My issue is no spark. I road for 45 minutes to camp last week. Ran fine. Stopped and visited for about 6 hours and went to leave and wouldnt start. Went through check list of ignition troubleshooting. Can say I found ground at tach bared. Unplugged harness. Did this cause my issue? No spark from coil using a spark plug as gap tester. Does that mean Thunderbolt IV amplifier is toast? If so can someone let me know what distributor system to purchase to replace the Thunderbolt IV system

 

[NHGuy]

If you still have the tach disconnected it's probably causing the no go. Hook it up (after insulating the bare part), and give er a try.

 

[yamjer]

If you still have the tach disconnected it's probably causing the no go. Hook it up (after insulating the bare part), and give er a try.

When I say bared wire it was bare from tach to harness connection! So the checklist for troubleshooting says to disconnect the tach wire from the coil. Wouldnt disconnecting the harness be the same? Did both.

 

[nola mike]

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

 

[yamjer]

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

Thanks for the response. I followed flow chart a couple days ago and still had no spark. I saw a post earlier about changing from Thunderbolt to a different distributor system.

 

[nola mike]

Thanks for the response. I followed flow chart a couple days ago and still had no spark. I saw a post earlier about changing from Thunderbolt to a different distributor system.

So the last step in that chart is to have a working ignition, you must not have followed it correctly. Putting in a new ignition will be more trouble than fixing the old.

 

[yamjer]

Thanks again. So chart says if no spark change Thunderbolt IV ignition, but have read (Don) says change distributor and rewire and never deal with Thunderbolt again. Didnt sound difficult when I read that. What would you do? I am going to rewire tach (change grounded wire that was burnt) and try the chart again.

 

[achris]

Deadman switch got tripped accidently? Do you have 12v on the coil+? (It's a purple wire.)

Chris.

 

[nola mike]

Thanks again. So chart says if no spark change Thunderbolt IV ignition, but have read (Don) says change distributor and rewire and never deal with Thunderbolt again. Didnt sound difficult when I read that. What would you do? I am going to rewire tach (change grounded wire that was burnt) and try the chart again.

Follow the chart, let us know where it breaks down. It's not a complicated system, an ignition module failure is really the only thing that *might* make it worthwhile to change systems. Relatively rare, easily found on eBay.

 

[yamjer]

Follow the chart, let us know where it breaks down. It's not a complicated system, an ignition module failure is really the only thing that *might* make it worthwhile to change systems. Relatively rare, easily found on eBI get 12 volts at the coil. No spark coming out. Used a spark plug as my gap tester and no spark.

Deadman switch got tripped accidently? Do you have 12v on the coil+? (It's a purple wire.)

Chris.

Yes Chris. 12 volts at coil.

 

[yamjer]

Follow the chart, let us know where it breaks down. It's not a complicated system, an ignition module failure is really the only thing that *might* make it worthwhile to change systems. Relatively rare, easily found on eBay.

Seems to break down at coil. 12 volts there. When doing the spark gap test, using a spark plug, no spark.

 

[yamjer]

Deadman switch got tripped accidently? Do you have 12v on the coil+? (It's a purple wire.)

Chris.

yes 12 volts at coil

 

[achris]

Seems to break down at coil. 12 volts there. When doing the spark gap test, using a spark plug, no spark.

Are you putting the spark plug into the end of the HT lead that was on the centre post of the distributor cap? Or into a spark plug leads that runs from the cap?

Chris...

 

[nola mike]

yes 12 volts at coil

What happens in the next step?

 

[yamjer]

Are you putting the spark plug into the end of the HT lead that was on the centre post of the distributor cap? Or into a spark plug leads that runs from the cap?

Chris...

On center post of distributor cap from coil.

 

[yamjer]

Are you putting the spark plug into the end of the HT lead that was on the centre post of the distributor cap? Or into a spark plug leads that runs from the cap?

Chris...

HT lead from coil

 

[yamjer]

What happens in the next step?
View attachment 365552

First time through had nothing happen. Will be back to boat Saturday and run through again.

 

[poconojoe]

Deadman switch got tripped accidently? Do you have 12v on the coil+? (It's a purple wire.)

Chris.

This is what I was thinking.
If the deadman switch is tripped, the engine will still crank, but won't start.

 

[yamjer]

This is what I was thinking.
If the deadman switch is tripped, the engine will still crank, but won't sI

 

[yamjer]

I agree but was getting 12v at coil.