When a "Slick Start" Fails
I know some of you have a Slick Start in your RV's. My RV isn't flying yet but I have one in my Maule. By the way, I think it has been helpful over the last 13 years --- especially with cold winter starts. It has a carburator so hot starts aren't an issue.
The other day I went out to fly and had a 600 RMP drop on the left mag. My GEM engine monitor showed that pairs of cylinders were affected. 1 and 3 running with high EGT and 3 and 4 with little or none. CHT followed the same pattern. Plugs were clean.
Having more or less forgotten that I had the Slick Start, thinking it was not likely to fail and would not be selective with cylinders if it did I ordered a new mag. The new mag didn't fix the problem and a subsequent check of the harness and each plug showed no faults. Running the engine rough on only the left mag produced hot cylinders on 1 and 2 and absolutely no temperature on 3 and 4. With nothing else left to check disconnected the Slick Start and the problem went away. Contacted Unison to get their view and they said that it is likely a relay "welded" and a diode grounded out. The mag produces high voltage in two polarities. One was completely cut by grounding through the Slick Start and the other unaffected and this caused failed ignition on two cylinders only.
Thought this might be useful info for anyone with a Slick Start who gets these same symptoms. Now I am so lucky to have a spare $720 mag!
Port Orange, FL
QB RV-8 completed!!
XIO-360-M1B with LASAR
GNS-430, GI-106A, GTX-330, 9000EX, Becker 4201, Digiflight II VSGV, ADI, Dynon Dlight Dek 180, Vertical Power VP-200