Thunderbolt IV problems

[cobia-boat]

I have a 1983 Chris Craft with a merc 350 and thunderbolt IV ignition. The motor is built a little bit, and I lost spark yesterday I have checked everything, even bought a new electronic sensor for 95 dollars and still no spark at the coil
I now believe the module wet bad. I swapped the distributor out last night with the old pionts set up off my other my other older boat and it fired right up.

My question is I don;t want to spend the 450 dollars for a new module, is there a cheaper set up that will work????? And still give electronic ignition, The pionts set up I'm guessing won't give me full potential on the motor.

 

[cobia-boat]

Re: Thunderbolt IV problems

I also timed it last night with the piojnts set up and it won't idle at less that 950 rpm and its at 42 degree advance to sound good.

 

[FreeBeeTony]

Re: Thunderbolt IV problems

42 deg BTDC sounds way too advanced............I would think you might have other probelms there.

 

[John_S]

Re: Thunderbolt IV problems

You might want to try to diagnois what is wrong with the T4 before trying to convert to something else. The link below might help. The SM for your engine is not online. This is for the BB, but should have similiar/same diags.

http://www.boatfix.com/merc/Servmanl/16/16B4R2.PDF

The standard timing for your engine should be around 6-10 initial, and about 30-34 for total advance. But check your manual.

 

[Limited-Time]

Re: Thunderbolt IV problems

If I'm correct the TB IV is a complete ignition system. It incorporates a knock sensor and computer controlled advance. It also requires a special timing procedure. So just changing to a points dist. wont be a viable fix. If I'm wrong I'm sure someone will chime in.

 

[Haut Medoc]

Re: Thunderbolt IV problems

With the key in run position, check for 12v @ the + side of the coil.......
If the answer is yes, check for 12v @ the white/red terminal on the distributer......
If no disconnect the white/red lead from the dist, then check for 12v....
If you have 12v replace the ign sensor in the dist.....
If you have 0 volts, replace the ign amplifier.......
I would stick with OEM on this, I don't believe that you can mix & match....​

 

[John_S]

Re: Thunderbolt IV problems

Limited-Time,

I think you are referring to Thunderbolt 5. T4 was a simple electronic ign with set adv curves. No knock sensors or fancy adaptive stuff.

 

[rad1026]

Re: Thunderbolt IV problems

John is correct, no special timing procedure either, like the V.

 

[Limited-Time]

Re: Thunderbolt IV problems

Limited-Time,

I think you are referring to Thunderbolt 5. T4 was a simple electronic ign with set adv curves. No knock sensors or fancy adaptive stuff.

I stand corrected. :redface::redface: