1987 K75S restoration...this one's gonna be "fun".

[Laitch]

The part number I found online for the knob I need (which is different from the Ebay offering) is discontinued pretty much everywhere.

The part number you found online for the knob you need differs from the eBay offering because the vendor doesn't realize that the part number on the bag in the photo is part of a telltale light assembly within the cluster and not for a knob of any kind. I tried to make that clear in post #47 but apparently did not succeed.

Below is the part that actually belongs to the number on the bag in the ad photo.

[Romonobyl]

Quick update:
The refurbished fuel nozzles came in and reinstalled easily after some very judicious cleaning. I temporarily put the tank in position with some bodged pump wiring and added a gallon of fresh gas. The good news is the pump operated normally and fuel was circulating through the tank, but I found a small leak at the tank nipple for the fuel hose from the pump, but only when the pump is running. It wasn't bad enough to keep me from giving the starter a go, but still no spark. Time to break out the multimeter...again.

Got 12VDC to the coils with the key in RUN, so far so good. The coils checked out at just under one ohm for the primary winding and about 12-13K on the secondary, works for me. Now the HT leads to the plugs? Nothing...zero, zilch, nada. Even at the highest setting I couldn't force a single electron down those wires. I made sure I had good contact with both terminals, but all three cables were wide open. My understanding is I should be getting about 6 Kohms, not even close.

I'm a bit surprised by this, I wouldn't expect something as relatively inert as spark plug wires to suffer total failure even after a lengthy indoor storage. Apparently I'm wrong. Looks like it's back to EME for a set of cables, fortunately they aren't too expensive. Meanwhile I'll investigate the tank leak.

I have a few pictures of the cleaning process I had to go through prior to the fuel nozzle install, I'll post them with a little more detail as I want to share what I learned. Thanks for reading!

[frankenduck]

K75 spark plug leads have a "resistive gap" in them. They're an open circuit if you apply an ohmmeter to them.

[Romonobyl]

K75 spark plug leads have a "resistive gap" in them. They're an open circuit if you apply an ohmmeter to them.

A little voice told me to hold off on ordering those cables. I did a search for troubleshooting the ignition system (obviously from some "lesser" website) and that's where I got those ohm readings from, but I also found it strange that all three cables were equally "bad". While it's good news that I didn't waste money on unnecessary new parts, now I'm going to have to dig deeper as to why I'm not getting any spark. I already disconnected and cleaned the connectors for both the ignition and fuel injection control units, I did the same to the ground lug under the tank. I know there's voltage going to the coils, but if I'm reading the wiring diagram correctly (a challenge as the aviation-grade schematics I'm familiar with use a very different format), the ICU controls the ignition pulses via the ground using data from the HES.

I guess it's back to the drawing board, I have a copy of Bert's troubleshooting guide and I'll have to patiently go through each step. Tedious but certainly better than just firing the parts cannon, especially considering how much the ammo costs.

Thanks as always Duck for the heads up, I appreciate how everyone has been patient with this newbie and keeping me from doing something stupid. Believe my I'll need all the help I can get in that department!

[Gabriel70]

Hi

Im thinking it might be a faulty ignition control unit.