Thunderbolt IV ignition problems. 3 coils in 2 days.

I have a 1990 Mercruiser 5.0LX with an Alpha 1 Gen 1 outdrive. My ignition system is a Thunderbolt IV system.
This is a new too me boat so I dont know what has been done to the boat.

Day1: Put the boat in the water ran it all day with only a few misses here and there. The engine sputtered and died at the end of the day. It would run fine at 2400 RPM's or less without any problems. If I throttled it up beyond that it would sputter and misfire and kick out some major rich exhaust fumes. No spark at the coil. If I waited about 10 minutes it would fire up but would die again if I would rev beyond 2400 RPM. I decided to replace the coil. The only parts place in town was an auto part store who sold me a coil with no internal resistor. I put it in the boat and it started right up.

Day 2: Ran 10 miles offshore and the boat died again checked the spark at the coil and no spark was present. Waited about 10 minutes and it would fire right back up. I took the first coil and the second coil in to the auto shop to be tested. They both were pretty weak. Went back to the auto parts store who told me it must have been an internal resistor type coil. I bought that coil and installed it. The engine started right up. We took off from the harbour and got about 12 miles out and the engine died. We limped back in, this time couldn't get over 2000 RPM's. We gave up and left for home.

Every mechanic that I have talked to said there must be a short or something somewhere.

I figured I would just replace the ignition system with a simpler 3 wire system from Max Volt when I realized that there was no provision for a shift kill switch.

Now I am back to troubleshouting the Thunderbolt system. I am going to replace the cap, rotor, coil, plugs and plug wires. Could there be a problem with the distributor sensor? So far I have been told that that cant be the problem because they either work or they dont. Can it be cracked and shorting? Could it be the Ignition Module?

Any help would be appreciated.

Thank You,
Glen Walker

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

If there was a problem I would suspect more the amplifier, not the sensor. I would suspect more the wrong coil or a ground problem somewhere. Is the ignition amplifier mounted to the exhaust elbow or on the distributor itself? One thing I would be checking for is that the distributor body has a ground wire on it. If it doesn't, ground it, with a wire from the dissy body to the engine block.

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

The amplifier is mounted on the exhaust riser.

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

Check all your grounds, especially the dissy...

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

Had a similar problem with my thunderbolt IV system also. It happened last spring.

Same thing would start fine,but would not rev past 2500 rpm - sputtered,cough,back fire and would not rev. Took out the thunderbolt system-dizzy and module and put my sons dizzy outa his boat - points system ( Chevy 305) tried it and all was good.....
With doing that i eliminated that the thunderbolt system was bad.

I bought a Mallory electronic ignition system (Marine Rated of course)..... Came with new dizzy,cap,coil and plug wires. Bolted up,set timing and go. Have not had one issue since.

Dont know if this is your problem or not. I spent many hours and money with throw at it parts and still issue was not resuvolved untill i switch systems.

Good luck! Hope you get it resolved.

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

81 Checkmate said:

Had a similar problem with my thunderbolt IV system also. It happened last spring.

Same thing would start fine,but would not rev past 2500 rpm - sputtered,cough,back fire and would not rev. Took out the thunderbolt system-dizzy and module and put my sons dizzy outa his boat - points system ( Chevy 305) tried it and all was good.....
With doing that i eliminated that the thunderbolt system was bad.

I bought a Mallory electronic ignition system (Marine Rated of course)..... Came with new dizzy,cap,coil and plug wires. Bolted up,set timing and go. Have not had one issue since.

Dont know if this is your problem or not. I spent many hours and money with throw at it parts and still issue was not resuvolved untill i switch systems.

Good luck! Hope you get it resolved.

Click to expand...

Do you have a shift kill switch? How did you wire it to the new system?

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

Do you have a shift kill switch? How did you wire it to the new system?

Yes everything was the same, it came with the proper wire hookup and directions for hook up. I called a Mallory rep on the set up and they guieded me thru. I think i paid around $400 for everything. Dizzy,cap,coil ,wires, and ballist resister. Look online and you can find all kinds of replacement ignition systems for your boat motor. Its a small block Chevy....... What more could you ask for.........
I looked for a new thunderbolt module and for the cost of a new or used one it was a no brainer for me to get a new electronic system. Plus i like the system i bought ( Mallory) cant go wrong with this product. You can get a different set up from Mich motors for about the same price, but i didn't like it.
I wanted something i could work on!

Good luck!

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

I purchased a whole new ignition kit. When I asked the tech support guy where the shift killl wire needed to go he said " There is no provision for a shift kill with an aftermarket system" so I had them take it back. I asked them what system did I need and he said "there is no system that will work with the shift kill". I thought that grounding the - post on the coil would work for the shift kil but he said " thats a good way to kill your coil".

Can you tell me the dizzy model number you have and tell me where your kill wire is wired into.

I have to have this boat fixed and 35 miles offshore Thursday morning. I need to order something today for next day delivery or I will lose an

I know Don will tell me to fix the Thunderbolt system but the cost of the amplifier and the fact that there might be an incurable short some where makes me want to change the whole system out.

Thank You, Glen Walker

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

Then go with the Delco EST distributor. It will work with the shift interrupt system.

Here is a link to view the instructions for one that another poster sent me pictures of.

http://www.4shared.com/office/Q0-h7UTz/Delco_Voyager_Kit.html

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

Here is that part number - Mallory Marine Products 9-26306 Replaces 18-5494-1

Don't have the boat..... its at the lake....

And YES the shift interrupter does work and i believe is does hook up to the coil as is was in stock form with the thunderbolt system, if my memory serves me right.

I have had the same coil in the boat from last spring till now and NO ISSUES.

Or do as Don suggested and get the Delco unit.

Good Luck!

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

I purchased a Maxvolt "Ready to Run" distributor and coil. It appears to be an MSD knock off. It works great. I hooked the shift kill to the coils negative terminal and it works perfectly.

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

Thats great...... Hope Your Bugging across the water......

Re: Thunderbolt IV ignition problems. 3 coils in 2 days.

81 Checkmate said:

Had a similar problem with my thunderbolt IV system also. It happened last spring.

Same thing would start fine,but would not rev past 2500 rpm - sputtered,cough,back fire and would not rev. Took out the thunderbolt system-dizzy and module and put my sons dizzy outa his boat - points system ( Chevy 305) tried it and all was good.....
With doing that i eliminated that the thunderbolt system was bad.

I bought a Mallory electronic ignition system (Marine Rated of course)..... Came with new dizzy,cap,coil and plug wires. Bolted up,set timing and go. Have not had one issue since.

Dont know if this is your problem or not. I spent many hours and money with throw at it parts and still issue was not resuvolved untill i switch systems.

Good luck! Hope you get it resolved.

Click to expand...

I have had many Mallory distributors over the years. They are very good quality and work great.

The module will however fail at some point and when they do, its done it wont work again. Make sure you buy and keep with you an extra module as you cant get them just anywhere. I would often sell my extra one, for a small profit of course lol, at the races.

They are very sensitive to stray voltage/voltage spikes, like jumper cables, battery chargers, booster boxes etc.