No Spark ? 1988 454 330hp Mercruiser Thunderbolt

[103Control]

Hello,

Well after my 22' 1988 Boston Whaler Temptation with a Mercruiser 454 BBC
330 hp Carburated , generation 4 , ThunderBolt ignition had just died out in the harbor, I pulled it out and I am working on it in the driveway.
I seem to have lost spark, when I push the throttle I do see gas squirting in the carb and the next thing I did was check for spark. nothing,
I used a volt - ohm - meter and it looked like the 12 volt feed to the coil was shorted so I took the feed conductors of the two terminals and brought a direct feed to the coil and it seemed to have a heavy load or a short so I went out and bought a new coil and tried that.
I hooked up the new coil all different ways with and without the parallel feed going to the Thunderbolt ignition box mounted on the manifold and still no spark
I pulled the distributor cap which was all new this summer and new plugs , wires' , rotor etc. and it all looks good to me.
SO I guess my next thing to replace is the "Thunder bolt Ignition IV" Box,
There does not seem like there is much else? BUT I figured I'ld ask here first to see if there is a way to test that box or even run the engine with out it?

 

[Bt Doctur]

Re: No Spark ? 1988 454 330hp Mercruiser Thunderbolt

a bad tach can kill the spark, it`s the grey lead on the main feed to the coil.
Yes, you need the box,it`s what provides the pulse.There is a specific test procedure for the Thunderbolt systems.
Have you checked the "safety lanyard switch" if equipped

 

[Chris1956]

Re: No Spark ? 1988 454 330hp Mercruiser Thunderbolt

You should invest in a manual. There is a troubleshooting flowchart which will pin down the culprit module. Remember, the T-Bolt ignitions are MerCruiser specific.

Even my Seloc helped me track down the broken component in my '88 MerCruiser's ignition. it turned out to be the module inside the distributor, BTW. I thought it too expensive to guess or replace all the components.

 

[dcg9381]

Re: No Spark ? 1988 454 330hp Mercruiser Thunderbolt

So I don't know much about the Tbolt ignition in particular, I'm sure you could get a manual that has a good diagnostic procedure.

Most ignition systems have 12v applied to the coil. The coil gets charged and sucessively fired by pulsing it to ground. It sounds like your coil isn't being pulsed to ground by the ignition system.

I'm sure someone with more marine ignition experience can give you a better answer.

 

[mkast]

Re: No Spark ? 1988 454 330hp Mercruiser Thunderbolt

First place I'd look is the sensor inside the distributor.

 

[Haut Medoc]

Re: No Spark ? 1988 454 330hp Mercruiser Thunderbolt

Try this......​

 

[103Control]

Re: No Spark ? 1988 454 330hp Mercruiser Thunderbolt

Thank You for the help on the Thunderbolt Ignition, I was hoping that by just swapping out the coil would do it and I by passed all the safety cut-offs by wiring the coil right to the battery and trying it but to no avail but now with the diagram and your passed down knowledge I have a clue on my next mission.
I did not know if the sensor in the distributor was a key component, it was called a knock sensor in one diagram I found but I see now how vital it is...
Of course now it's raining so I'll have to wait a bit to follow through but I'll post back as I progress.
All summer long the engine was running great, I USUALLY just run it at 2800 to 3500 rpms but on the last day I used her I noticed the temperature rose up to 200 degrees when at 3500 so I backed it down to 2500 and it cooled off to the normal 175 degree mark. Then I shut it down, dove in and scrubbed around the Bravos water inlet holes, removing the barnacles and growth there. Tried it again and noticed that my top rpm was only 3900 and it started to get warm again so I was thinking it might be time for new exhaust manifolds ? so I just kept it at 2200 and was heading back to port when I could not even maintain 800 rpms and then it quit so perhaps it was electronic all the time?
I hope to get her running again to drop her in for one more WOT spin to see if it does need new exhaust manifolds or not, but when in the driveway I noticed it still had a lot of inlet holes blocked, or maybe I need new pumps.
Thanks very much for the expert direction folks....
AL

 

[Haut Medoc]

Re: No Spark ? 1988 454 330hp Mercruiser Thunderbolt

If that is the case, you might want to pull the plugs, spin the engine & make sure you have no water intrusion......​

 

[Chris1956]

Re: No Spark ? 1988 454 330hp Mercruiser Thunderbolt

Al, On my '88 MerCruiser the module inside the distributor was the reluctor(solid state trigger mechanism). The reluctor replaces points in a conventional ignition system. if it is faulty, the coil will not fire.