Re: no spark on either plug johnson 4 hp 1973 model
Hi Ben,<br /> A couple of things to check...<br /> Are you grounding the metal housing of the plug to the motor block when you check for spark? The spark must be able to complete the circuit to arc across the gap.<br /> Also, the shock but no arc may indicate a pair of bad condensers under the flywheel. The condensers hold the charge momentarily and let it go when the points open. If the condensers are bad the spark may be letting go over a longer period of time with less power. Condensers are cheap and easy to replace - less than $10.00. Clean and gap the points at .020", replace if they look badly pitted or excessively worn. The coils should be fine, as the 1970s vintage coils used a better plastic insulation than the earlier ones and seem to survive quite well. Use a proper 3-point harmonic type puller to yank the flywheel off... They have them as Sears, NAPA, etc. The bolt holes are 1/4"-20-thread. Use quality cap screws instead of standard issue hardware store bolts.<br /> Good luck!<br />- Scott
