Today's engine puzzler #2

[scsmith]

Sinking float or stuck float-bowl needle valve.

[rv6n6r]

Well it's time for the solution to this week's puzzler. Some valiant attempts but no one got it.

The clue was my mention of iridium lifetime plugs. I could have put "lifetime" in quotes but I thought that would make it too easy.

I found the solution when I watched an EAA webinar on RV maintenance by Vic Syracuse, during which he mentioned hard starting as a symptom of the internal resistors breaking down in plugs that otherwise look fine. I never knew to check that so I did so and all of them were way over the recommended max of 5000 ohms, and at least one was infinite. It turns out these "lifetime" plugs (for which I paid nearly $100 ea. 12 or so years ago), have this problem where the resistors break down regardless of their "lifetime" claim (and cost). Vic mentions this in at least two EAA RV webinars and Mike Busch has talked about it in engine webinars and articles as well.
https://eaa.org/Videos/Webinars/Airc.../6115329634001
https://blog.aopa.org/aopa/2015/03/1...to-acceptance/

Champion claims to have fixed the problem but I'm done paying that much for spark plugs that may or may not last, so I replaced the "lifetime" plugs with the regular kind (from Unison). I've also since switched the P-Mag harness to an automotive plug harness (which is all that they offer now anyway) and am using throwaway automotive plugs with that.

As for the starter fluid, I would guess that helped because there was still some spark, just not enough for starting without that extra "oomph". Plus it turned out to be a nice obfuscation in the tradition of click and clack!

To me a side message is, go watch the EAA's RV maintenance webinars by Vic Syracuse AND similar webinars about engines by Mike Busch. Fantastic resources that hit many of the highlights of what we typically run into in RV maintenance-land.

[RV10inOz]

These will have been the old Champion plugs. If you look in the hole where the plug lead goes, the old design have a screw driver slot in the base. New ones, or Tempest do not.

That high resistance is hard on the coils of mags too apparently.

[spark68]

Good one Randall! I used to listen to Click and Clack every Saturday morning and loved the puzzlers and especially the "write your answer on a (whatever) and send it...

Thanks for sharing.

[esco]

Tommie and Ray Magliozzi would be proud of you.

Now all you need is advice from Dewey, Cheatham, and Howe.

[Flyingleap]

Every annual I check the resistance of my plugs. Never let them go over 2000 ohms.
BTW... I have had one in ten new Tempest plugs (after maybe 50 hrs ) show "open". I think they have fixed the problem though. They will replace "open" plugs unless they were purchased in 1975. John