Testing Ignition Coil - no continuity?

[gsbarry]

I’m trying to track down the cause of hard starting when cold (takes roughly 10-15 five second cranks, including throttle pumps, to start, starts well when warm, runs and idles well). This is on a 2015 3.0L, low hours. Compression test is good. Full tune up (plugs, wires, cap, rotor, fuel filter), oil change, fresh fuel, removed carb and spayed carb cleaner through it (looked clean start with though).

I went to check the resistance on the ignition coil, following the service manual procedure, but it’s really strange, on every terminal combination I’m just getting an open circuit reading (i.e. no continuity). I spent a good 20 minutes, tried different test leads, new multimeter, continuity checks touching leads together.

I’m really scratching my head on this one. If there actually was no continuity at all I would think that the motor wouldn’t fire/run at all, which it does just fine once warm.

What do y’all think?

 

[Candy Gramformongo]

You might be overthinking it. Get a new coil and swap it in. Does not even have to be fully attached. A couple of zip ties will do. If that fixes things, swap it in properly.

 

[cyclops222]

Automatic choke is stuck WIDE OPEN. NO CHOKE function.

 

[Bondo]

I’m trying to track down the cause of hard starting when cold (takes roughly 10-15 five second cranks, including throttle pumps, to start,

Ayuh,..... For a carbed motor, that don't sound bad,....
It might take 1/2 that time to fill the carb, pumping the throttle before that does nothing,...
Is the choke, or tks system working,..??
Afterall, it's a carbed motor, not an Efi like yer car,....

 

[gsbarry]

Yeah, I get it’s not efi, not expecting it to fire up immediately, just seems like an excessively hard start. This is a tks carb. I pulled the tks unit off the carb to inspect and it seems fine visually. Though I’m not sure if there’s a way to test it.

It does seem to make some sense that the tks (aka choke) is not functioning correctly. Any ideas on how to confirm this? It looks like the tks “enrichment module” is ~$400 (which seems ridiculous) so I’d rather not swap one in on a whim.

 

[cyclops222]

delete

 

[gsbarry]

I decided to pull off the TKS enrichment module and bench tested it by applying 12 volts for ~5-10 mins. The module warmed up to the touch on the back (as expected), and the plunger also slowly extended ~10mm (as expected, not sure what the extension range spec is though). I also gave the TKS bore another visual inspection and spray down with carb cleaner. I’ll report back next time I get a chance to fire it up.

Thinking back, last cold startup I actually don’t recall hearing the “whistle” that most people observe on cold TKS starts, which suggests the plunger may have been stuck closed (not sure on this though).

 

[gsbarry]

Problem solved! The engine fired up much easier today, and I observed the whistle as expected from the TKS unit during warmup, which then went away after a few minutes. I’m fairly sure that I dislodged a small particle of debris from the TKS bore the other day when I was spraying carb cleaner through it, and that’s what I’m attributing to the improved starting. Thanks all for the help.