Join Date: Jan 2005
Location: St Marys, Ohio, USA
Anyone heard of a procedure or spec on gapping the pulse generator (PG) coils in an 84? The Clymer manual (with major errors in the electrical section) says "not adjustable" and "0.016 - 0.040" range (which is odd since its "not adjustable").
Heres the scenario. Removed engine, then Right PG (Yellow) but not the Left, removed housing, reinstalled. Left PG is now dead (the one that wasn't removed from the case). 5 Vpp AC on Left (Blue), 60 Vpp Ac on Right (Yellow) per oscilloscope. Engine started and ran on two cylinders driven from the Right PG with the other two firing occasionally (Left PG). The PG that hadn't been removed had failed.
Removed PG housing and measured/calculated stack ups and found the PG's are adjustable from interference to + 0.049" with significant rotation. Tested the PGs on a test stand and read a slight difference in voltage, but nothing like the difference when installed.
Gapped both at 0.016" and reinstalled the housing, now they are both low voltage, about 15V PP. Installed gaps are 0.016" Left and 0.020" Right which is good considering I gapped them before installation. Engine wouldnt start last night although the battery was weak and I didnt use the choke.
The PG'sread within 5% on resistance / inductance and mechanically. The Left one has a slightly weaker magnet. The PG's have a magnetic strip on front, they are in position (toward the rotor) within about 0.005" of each other.
A new set of pulse coils mightfix it, but we dont learn anything that way, not to mention that "throwing parts on" is illegal in many US States. Next step is to close the gaps incrementally and see if the pulse voltages increase and if enginestarts to run.
Two odd things:
1.) The Yellow one, which I initially removed and put back in the case with no alignment done, was at 60V, while the one I didnt touch was low. Should have been the Yellow one that misfired, but it wasnt.
2.)The replacement parts are sold already installed in the PG case which makes me think the alignment is very critical.
What gives? Where Brojees my EE mate?