2000 Safari. Family school bus is dead...

[zubzub]

I'm going to try to slip this problem in here as I have googled it to death and I am not making progress. 
Gm EDI system  (ignition) with CSFI (fuel injection) on a 4.3L V6.

I have trouble shot the coil.  Basically I have no start due to weak spark.
If I check spark during cranking I get a weak orange spark...
BUT just when I stop cranking I get one decent spark, nice high tension blue one that even zaps me through my needle nose pliers. (I can also hear ignition at this point....but not enough to start)
I have checked for power at various points on coil etc and it is not a case of no power during cranking (like with a blown ballast resistor but the opposite).
I am hoping someone recognizes this symptom as it is cold out and getting around this engine is difficult as there is  van surrounding the hole damn engine.
There are nice even timed weak orange sparks during cranking
the coil test out pretty good though spec resistance in the winding is 0.1ohm and I am getting 0.3 but as it is cold outside and my M meter needs a new battery I am hoping that is alright....changed coil last year.
I think the real clue is the hot spark when I stop cranking but I don't know what it means.
I hope this stays up for a bit, it is the wife's Safari and is used a the school bus (4 kids) so maybe it qualifies.
Any hints appreciated.
p.s. I can smell fuel and hear a partial ignition on stop crank so I presume I have fuel....maybe I should get some ether to see.

[Emcemv]

Sometimes this happens when the battery voltage drops too much during cranking. When you stop cranking the voltage jumps up and you see one good spark. Many reasons for this, bad connections, weak battery. Try jumping it, that may keep the voltage higher. If it starts, you know what the problem is.

[06 Bill]

That problem usually relates to low voltage during the crank cycle. When you release the start button the engine
coast effect along with higher voltage will give you good spark or two. Try a strong jump - charge the battery- a new
battery. My Honda motorcycle will not start while cranking but does start when I release the start button. A new battery fixes it every time.  Good luck 06 Bill

[zubzub]

OK i'll recharge the battery, but I am getting a nice fast crank and no fade from the battery so I kind of don't think so......I also read that the spark plugs on this engine are spec'ed pretty open so sad sparks don't jump...

[robertglines1]

Ign switch? release to run spot differant power feed to coil? Might even just make sure wiring harness to side of switch on lower steering collom(sp) is corrosion free.  Good luck!  Bob

[bansil]

Maybe dirty battery connections,the starter is pulling to many amps to crank and not allowing enuf to ign?
Maybe starter is dirty inside from oil/dirt which is pulling the amps down?
Good luck with this.

[Len Silva]

Just for troubleshooting, try using another battery just for ignition.  My first suspicion when there is a strange problem like that is bad grounds.  For some reason, the starter is dragging the voltage down.  Bad starter, bad grounds, bad battery.

[Hobie]

If the coil tests ok, and the ignition key is giving good power, and it cranks hard, and you smell gas,  check timing.  Have you verified that distributor has not skipped a tooth/stripped dizzy gear?  Good Luck!!

[zubzub]

The thing that bugs me is the weak spark.  In my searches online it seemed pretty clear that this engine will not start without a nice spark, and the spark straight off the coil is orange and weak, except for the last one when not crank ends)  I will charge the battery tomorrow and try an alt source of 12v for the ignition while cranking....
I tested for power at the coil and various other points after the ECM (the 12v is fed out of the ECM  for timing etc) and everything has juice, cranking and in on position.  I have fixed  plenty of gas engines over the years but truth be told this is the most "modern" ignition system I have fiddled with.  Spent 45 minutes studying the wiring diagram today, have a pretty good idea of how it all works, just a little confused.....
Thanks to everyone for their thoughts, I'll try everything untill something gives....

[plyonsMC9]

What happened? Just curious - it's been 10 days - was one of these 'the fix' ?  Need more suggestions?

Kind Regards, Phil

[zubzub]

I am flummoxed.... went down to -25C and it started right up.  No problems since.  It is +5 C and raining today so we will see.  For me this is moisture related but I don't know where.  At this point  the ignition system is obsolete  and many who want to keep this  engine running  use a different  aftermarket  one (can't remember the name right now)....this is a van on it's last  legs so it is a hard sell.   Anyhow today we will see.

[plyonsMC9]

Thanks Zubzub, please keep us posted.  Hoping for the best.

Kind Regards, Phil