Generac

[Bill Hazelbakerxads]

I know this is not a garden tractor but I have read and respected most opinions on this forum. Have a generac 990 twin cylinder with no spark. Can take the ground off each module and get spark. What to do next? Also what should the gap be from the flywheel to the coil?
 

[joe csuti]

If eng a briggs intek v twin or a vanguard v twin the coil air gap is .008"-.012" on both.

As far as ign problem,intek & late model vanguard eng use a Y ign kill lead,there is a diode installed in each leg of Y that connect to coils to isolate coils from each other,if one of the diodes go bad it usually takes out both cyl,disconnect the kill lead at each coil,crank eng & check for spark,if you have spark now replace the Y lead.Lead can be ordered thru most briggs dealers,take eng mod/type numbers with you.

If eng an early vanguard eng will have a ground block mounted on eng with 3 quick disconnect terminals,disconnect kill lead to each coil from block,crank eng & check for spark,if you have spark now replace block,isolation diodes in block bad.
 

[joe csuti]

As a quick followup,before condeming ground block if eng an early vanguard,disconnect lead on ground block to stop sw or ign sw,check operation of sw with an ohmmeter or battery powered test light,sw may be bad.
 

[t.r.k.]

I assume you have a genuine generac engine.

Have you tried it with the ground wires connected to each coil and the other end of the wire disconnected from the chassis wiring? If you still have spark, the problem is on the chassis somewhere.

If your spark goes away then, its probably the wire shorted/pinched somewhere. Or else the diodes in the circuit. The diodes are probably in the wire under the insulation, but sometimes are in the coils.

If its on a generator, some have a stop switch in the electrical panel. Be sure its 'on'.