Starter button "magic" switch for clean running

[schrocketeer]

For my '86 K100 it will start easily and consistently, but at very low RPMs, ~800 RPM. Took on a 5 mile test ride. Had to feather the clutch and blip the throttle. Will not maintain steady RPM for a given throttle. Continously cycling the throttle will get it accelerate, but with hesitation.

Oddity, as long as I hold the Starter button down, the engine revs as expected. As revs go up, speedometer needle moves.
If I let go of the Starter button, it revs erratically.
I've pulled the handlebar module with the Starter/Kill switch, and verified the Starter contacts are clean. Sprayed with Contact Cleaner, and applied Dielectric Grease.

FYI the headlight does not go out while Starter button is pushed if the engine is running.

Swapped the Load Shedding Relay. No change.

At Start, headlight does go out. Once running, pushing Starter button does Not cause headlight to go out, and revs will rise cleanly while pushing. As revs go up, speedometer needle moves. At initial Start, pushing the Starter causes the headlight to go out (i.e. Load Shedding Relay seems to be working).

Green wire at the ignition switch is good solder. Wire coming out of the switch passes the cable wiggle test. The bundle coming off of the Starter button also passes the wiggle test

Second oddity, when I spray carb cleaner around the Fuel Pressure Regulator on my '86 K100, it runs smoother and accelerates cleanly. "Normal" starting idle with carb cleaner. Holds a steady RPMs for a given throttle, as long as I keep spraying. Without carb cleaner, engine revs only build up with throttle opening surging (open/close, open/close, quickly repeatedly).

I've put almost 1k miles on this summer (acquired late Spring). However, it showed hard, hot starting. Other than that it was running great. Thought it was the Coolant Sensor, or the Throttle Position Sensor.

In the last month: new fuel lines in/out of the Regulator. New coolant sensor, Hall effect sensor. Swapped in spare Throttle Position Sensor (set to "click"). Fresh Ethanol free, 93 Octane fuel. New NAPA fuel filter, Intake boots.

Not sure what failed, or I bumped/messed with, installing these parts?

[schrocketeer]

Elbow hose on back left of engine is new'ish. No change in revs spraying carb cleaner on/around it.

[schrocketeer]

Would a bad Air Flow Meter cause this problem?

[daveson]

Oddity, as long as I hold the Starter button down, the engine revs as expected. As revs go up, speedometer needle moves.
This adds weight to the other symptoms of a lean mix. In cranking mode, the mixture is enriched.
If the Speedo moves while your bike is in neutral, thats a problem.

FYI the headlight does not go out while Starter button is pushed if the engine is running.
Thats normal. The ignition control unit will deny earth to the starter relay if the engine is running.

Second oddity, when I spray carb cleaner around the Fuel Pressure Regulator on my '86 K100, it runs smoother and accelerates cleanly.
Try to narrow down the location of this problem. Possibility of a split in the fuel pressure regulator vacuum hose, or it has come off its barb and is sucking air in. Also this is near the air filter assembly. Maybe an air filter gasket is not properly seated, possibly even  allowing unfiltered air to enter the system.

[schrocketeer]

If the Air Flow Meter has a bad "spot" in the vane pickup, would that mess up the fuel air ratio, and lean it out?

I'm thinking to take the AFM apart, and clean up the Contacts, etc.

Understand these are for a BMW car, but the AFM looks similar to and

[Laitch]

If your Brick idles normally by spraying carb cleaner on the fuel pressure regulator, find out why before doing anything else.

[schrocketeer]

Redid the clamps on #4 Intake Boot, and carb cleaner has no effect on the running condition.

Headed to the AFM next, as I have a spare to play with. Starting with measurements of Vane and Temperature. Will clean up, if needed.

[Laitch]

Redid the clamps on #4 Intake Boot, and carb cleaner has no effect on the running condition.

Are you indicating the spraying of carb cleaner on the fuel pressure regulator while the engine is running no longer makes it run smoother as asserted in your opening post? If it still does, I'm guessing that one or more of the throttle body manifolds is leaking. Redirect the spray at the base of each throttle body and use the little straw on the nozzle to be exact with the spray.
Could problems with the AFM lean out the mixture? Sure, but the fuel mixture shouldn't be enriched when spraying the fuel pressure regulator or the bases of the manifolds where they join the block. The roots of that condition should be understood before moving on.

[schrocketeer]

Re-did #4 intake boot clamps. Swapped Air Flow Meter. Cleaned and re-gapped spark plugs.
Massively rotated Hall Effect Sensor, maybe 20 degrees from where a feeler gauge tripped the LED test on both top and bottom sensors. Photo shows Sharpie alignment marks from LED test lineup.
Went from 60% stumbling/wouldn't idle to 15%.
On test ride, it could hold at 55mph. Blipping the throttle I could get maybe 65mph in 5th gear.

[Laitch]

In a previous post, I was referring to the manifolds themselves having leaks rather than the boots that are attached to them, but that ship has sailed.

This project needs to restart from Square 1—correct timing procedure by the book. Expecting it to run well in its present state of tune is unrealistic. I'm still back at the revs increasing when the fpr was sprayed with carb cleaner; however, that obsession is my own. I would have understood why that was happening before other measures were undertaken.

When the ignition timing has been restored to its correct value, this hunt would continue. If this were my albatross, I'd remove the timing cover entirely, set the #1 cylinder at the proper ignition angle at compression stroke, then view the alignment of the crankshaft pointer and the engine case timing mark along with the alignment of the camshaft sprockets' notches with crankcase/cylinder head joint. Only after those elements were in correct alignment would I start reassembling and backing out.

If I had a dozen years as a professional mechanic working on engines from flathead fours to supercharged V10s, I might be able to tune this Brick by guess-and-by-gosh or by ear, but instead I just go by the book using tools that seem appropriate for a piece of German engineering beyond a '59 Beetle engine powered by a Solex carb and a distributor.

It could be that a faulty ignition control unit or fuel injection control unit is at the root of all this but until the timing is verified as accurate or restored, I couldn't invest in either.

[schrocketeer]

I've only got 8.2 Volts to Jetronic pin 4. About the same at the Starter button. Blowing fuse #1 during troubleshooting.
Guessing what's behind this, is what "smelled" like all the other oddities.

Will report back when I find the flaky wire/connector.

Thanks for your help.

[schrocketeer]

Pro tip: do NOT use tie wraps to (not really) seal the intake boots between the throttle bodies and block. :-(

[schrocketeer]

Video link from Sunday. I could ride my '86 K100 pretty "normal" IF I held down the Starter button the whole time. https://www.facebook.com/share/1CiVa4yVxf/
From what you can hear, may I please have some more hints as to where to investigate next?

[Laitch]

At this point, I believe a numbered list of all tests and treatments you have done in the order in which they were done would be helpful for you to set down here so prospective respondents won't need to get mired in researching all your previous posts, or suggest measures you've already tried.

[schrocketeer]

Thank you Laitch.
Reasonable guidance to not burden the community.
Helpful for me to documents for myself and any future requests in an orderly fashion.
Cheers

[schrocketeer]

It was injector o-rings leaks and low fuel pressure.
Nothing to do with Electrical.
New o-rings, plugs, fuel pump, everything's happy.

[Laitch]

 

[Atabeach]

….there is a moral to this story somewhere.

[Laitch]

He that seeketh findeth. Matthew 7:8