The spark is to be tested with "all" spark plugs removed and having the spark jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! The gap is important!

********************
(Spark Tester - Home Made)
(J. Reeves)

You can use a medium size philips screwdriver (#2 I believe) inserted into the spark plug boot spring connector, then hold the screwdriver shank approximately 7/16" away from the block to check the spark or build the following:

A spark tester can be made with a piece of 1x4 or 1x6, drive a few finishing nails through it, then bend the pointed ends at a right angle. You can then adjust the gap by simply twisting the nail(s). Solder a spark plug wire to one which you can connect to the spark plug boots, and a ground wire of some kind to the other to connect to the powerhead somewhere. Use small alligator clips on the other end of the wires to connect to ground and to the spark plug connector that exists inside of the rubber plug boot.

Using the above, one could easily build a spark tester whereas they could connect 2, 4, 6, or 8 cylinders all at one time. The ground nail being straight up, the others being bent, aimed at the ground nail. A typical 4 cylinder tester follows:

..........X1..........X2

.................X..(grd)

..........X3..........X4

The wiring diagram would be included with a good quality Service Manual that is specifically for that one engine which should be available from your dealership, or possibly this site. If not, check with your local library as they usually stock them.

Evidently the vro system has to be connected in order for the motor to work. Once hosed were conceded,(minus the oil) the engine started up.