Thunderbolt Ignition

Any know anything about this?

Wierd thing yesterday, put the boat and it was really struggling to start, normally it goes easily from stone cold.

Plenty of fuel so suspected sparks (rotor, cap, leads and coil all new this year and timing set with light about a month ago)pulled a lead and sure enough a puny yellow spark. Was limited what I could do at the lake, but gave everything a good wipe down and a spray of WD40.

Eventually it started but only on about four, raggy idle, popping and banging back through the carb, wouldn't rev at all. Left it ticking over a bit to see if it smoothed out, it didn't.

Decided I'd pull the leads to narrow down which ones were missing. Picked a lead at random and pulled it, instantly smoother, put it back on and it ran like a champ for the rest of the day - WTF?

It was like the ingnition was confused about the crank/dist postion and was firing the wrong cylinder and pulling the lead put it back on the right track. Is that possible? I wouldn't have thought the system was complex enough to get "confused".

That was my last day of the season, so I'll have to see if it'll go when I bring it home to winterise.

It's 5.7 bluewater 260hp.

I think it's a thunderbolt v setup, but it may be iv vi. Probably should have looked at that!

One thing I forgot to mention was that the dizzy was sort of ticking with the ingnition on - sounded a bit like a fuel pump and the tacho needle was pinging about all over.

sounds like a crossed spark plug wire

I have seen this very same symptom with a GM distributor. I'm not sure if GM supplys the Thunderbolt distributor but I think they do. It turned out to be the pickup module inside the distributor.    

Hi - Years ago I had a Ford Small Block (Sunbeam Tiger)& had a similar miss.

A drag racer friend knew exactly what the problem was - cross firing.

On those motors, if certain plug wires crossed closely, the spark would jump to the wrong cylinder.

I re-routed the offending wires & it cleared up.

Could be a possible cause on your boat.

Chris

Tomski How long has it been sence you changed the cap & wires?

Well this one rears its head again!

Ran fine when I fired it up after the winter with new leads, plugs, cap and rotor. Came to it yesterday and the same problem back again.

I'm just waiting for a call to discuss with an engineer whether the hall sensor is the likely problem.

I assume T/bolt works like most such systems in that the hall sensor generates a pulse and the unit botled to the riser is an amplifier that ups the pulse to a level suitable to trigger the coil.

Could it be the coil? I doubt it is, since it's not lacking sparks, in fact it's got too many!

Any advice welcome.

On balance I think Nutty probably had it right, seems the most logical problem.

GottaSki wrote: I've always had sh|tty luck with wd40 inside dist caps, seams to promote crossfiring. I suggest brake cleaner of contact cleaner.

I suggest don't spray anything in it. If it has carbon tracks or if the terminals have crap on them.....then replace the damn cap because it's shot.... spraying this and that is bull shade tree crap and is only going to cause more trouble so replace it with a new quailty cap.