DSII swap, spark but no fire

Is the module grounded? Is the distributor properly installed (not 180 out)?

Pull the coil wire from the distributor and place it near a ground. Spin the engine. If the system is working you'll see a large spark on each firing event. That would lead me to think the distributor isn't in right, the cap and rotor are not transferring spark, or the plugs/plug wires are bad.
 
plug and wires are brand new
i think the module might not be fully grounded, so i'm gonna play with that when i get home

i tried swapping the wires across the dzzy to make sure that it wasn't 180* out, but that didn't even produce a backfire as it does when i try spinning it with it wired up normally
 
Is the coil the same one? Check it's not burned out. Check the grounds, like Jack says. Check incoming voltage. Check the DSII's own coil (the two wires to the module, from the dizzy) for continuity.

Both the coil side terminals are ungrounded, right? One side goes to the GM output for pos, one to the output for neg. You can also make a ground strap that has an eyelet each end, fixed through one of the module mounting screws. Allow plenty of current capacity (use the MSD wire gauge recommendations as a guide).

My experience with burned-out Bosch modules is a very weak orange spark once only when the ignition's turned on. I suspect a transistor failure in the GM unit would do similar. It doesn't go open circuit, basically just stops amplifying.
 
same coil
i pulled the coil plug, put a screwdriver in it and laid it against a ground, got a nice fat blue spark from it

grounds are good, both coil terminals are ungrounded, i'll try and find a fluke meter and check the voltage through it
 
On at least one ocassion I was very embarassed to discover that I had forgotten to install the rotor...... :oops:

Since it is making good sparks it narrows it down to either spark transfer through the cap/rotor/wires or an indexing/timing issue as Jack mentioned above. Make sure you are getting spark to the plugs, then double-check the timing.
Joe
 
Make sure the fireing order is in the right direction not just 180 off pull the cap turn motor with starter and see which way it goes and dubble check the order.
tim
 
I have also seen the rotor have a small pinhole in the top which grounds thru the dist shaft.

If you have the wrong rotor it will not be long enough for the DSII cap.
 
i haven't pulled a plug and checked to make sure it's sparking, but i pulled one of the wires and did the screwdriver trick and once again had a nice fat blue spark

pedal2themetal45":2j1rjnit said:
Make sure the fireing order is in the right direction not just 180 off pull the cap turn motor with starter and see which way it goes and dubble check the order.
tim
Click to expand...

clockwise, right?
 
what should all the voltage readings be?
or should i even worry 'bout that since we know i've got spark?
 
You want 12V at the coil, 12V into the module with key on, perfect grounds to the dizzy, heatsink, and module fixing eyes (at least one will have a brass or nickeled eye rivet).

Resistances of no more than 6K per lead.

Check for continuity of the coil pickup (two wires out of DS-II).

If the module is blown, you will get one spark only from the coil upon switching 12V to it (module). Then it plays dead.
 
It sparks repeatedly when you crank it?

Well - plugs, leads, rotor, cap to check and it will go. 200% sure on the timing?
 
sparks repeatedly
not sure on the timing, but seeing as i've reversed it to what it would be if it was 180* out, i don't see how that could be that...

i really don't want to pull this thing out again... it was enough of a PITA the first time
 
Pour a splash of fuel down the venturi.

If still no go, then swap leads one position at a time until it catches. Leave dizzy loosely clamped and you can try advance and retard on each of these settings.
 
it's getting fuel
i'm worried that it's dumping enough, and that it's cranking enough to wash the cylinder walls...

guess i get to play with it when i get off work
 
All right, get back to basics. Take the motor to #1 TDC compression. You could verify compression by jamming a length of hose in the plug hole and blowing into it. Airflow = exhaust stroke (wrong). Obstruction = good.

Now pop the dissy cap and inspect the centre button and all contacts. also look at the rotor for damage. The six teeth on the DS-II wheel should be positioned so that one is almost exactly amidships on the pickup coil. If it isn't, adjust it so this is the case.

Whichever terminal the rotor is pointing at, or closest to directly at, is the #1 coil terminal. That should get it started.
 
don't you hate it when you say "i checked that" but it turns out you didn't check it enough?

now my firing order is 362415
:?

but it runs... with my truck's battery, i killed the old one, which is too bad cause it was a loyal lil battery
maybe i can get it charged...
 
HI
That fireing order don't sound right???? :shock: The fireing order should be stamped on the intake log.... Varafi #1 TDC on the dizzy.. I think it should at about 11 o'clock with the vacuum advance at about 4 o'clock. eather way look at the rotor to make sure thats where it is pointing. It realy depends on how you installed the dizzy and to which one YOU desingnated as #1.. so #1 could be anyware on the cap as long as at TDC the rotor is pointing at it and the fireing order is corect from there.
AT TDC of the compression stroke the rotor should be pointing to #1 plug wire in the cap.. remember that the TDC comes up twice once for compression and once for exhaust... #1 and #6 should be across from each other on the cap not next to..
Let us know how it goes
tim
 
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