Itinerant Air-Cooled

Start with this overview.
http://itinerant-air-cooled.com/viewtop ... highlight=

Amskeptic wrote:Start with this overview.
http://itinerant-air-cooled.com/viewtop ... highlight=

I would like any member here to write an explanation of the what the diodes do. This will help me re-write and clarify the article.
ColinItIs6YearsLaterAlready

Amskeptic wrote:

Amskeptic wrote:Start with this overview.
http://itinerant-air-cooled.com/viewtop ... highlight=

I would like any member here to write an explanation of the what the diodes do. This will help me re-write and clarify the article.
ColinItIs6YearsLaterAlready

Please feel free to write your explanation here. We are NOT looking for a definitive answer from you, I just want to see how you picture it, how you explain it, what you choose to explain, and then I can get a feel for how to make edits to the article.
Step on up, you chickens . . .
Colin

(for example, I do not know a thing about local area networks. Here's my explanation of how they work:
A local area network in a corporate milieu allows individual computers to access other computers. A network can be set up to allow peer-to-peer sharing between computers, or to have a hierarchy with a "server", with all the good stuff, and "clients" that access it. Clients are allowed to "read" servers, but they cannot "write" to servers, thus they are like DIODES THAT CAN ONLY PASS ELECTRICITY IN ONE DIRECTION, HELLO)

Two things can trigger a fuel pump relay, battery voltage from the key in start position (50) and a reading from the Air Flow Meter. When the Air Flow Meter is sensing air from a running engine and putting out voltage, the diode (which is a one-way valve) prevents that newly discovered voltage from backfeeding up to the starter and activating the starting curcuit. If the starting circuit was activated, then I think the Cold Start Valve would activate under these conditions as well. If not, blame my high-school-physics level of electrical diagrams, not the article text.

asiab3 wrote:Two things can trigger a fuel pump relay, battery voltage from the key in start position (50) and a reading from the Air Flow Meter. When the Air Flow Meter is sensing air from a running engine and putting out voltage, the diode (which is a one-way valve) prevents that newly discovered voltage from backfeeding up to the starter and activating the starting circuit.

If the starting circuit was activated, then I think the Cold Start Valve would activate under these conditions as well. If not, blame my high-school-physics level of electrical diagrams, not the article text.

Wow, nicely done.
We would not be worrying about the cold start valve activating (the thermo-time switch interrupts the ground in seconds), we would be worrying about where all the little broken flywheel teeth would go, would they embed in the bell housing along with the exploded starter pinion?
Colin
(no, not really, the voltage supply to the fuel pump relay is unable to actually activate the starter solenoid, but a failed diode would pull the fuel pump relay open, and kill the engine)

Amskeptic wrote:(...the voltage supply to the fuel pump relay is unable to actually activate the starter solenoid, but a failed diode would pull the fuel pump relay open, and kill the engine)

Would it be the voltage or the amperage/current not able to activate the starter solenoid?

How would the failed diode would negate the fuel pump relay, because you would have +12v on both sides of the relay, which would be like no total current at all, correct? Just like the generator light in a T1 setup?

EDIT: and if the starter circuit DID get activated, wouldn't the starter temporarily turned into a generator, but with no output beacuse the solenoid is interrupting any current? Would that melt some wires too?

asiab3 wrote: How would the failed diode would negate the fuel pump relay, because you would have +12v on both sides of the relay, which would be like no total current at all, correct?

Nope, the 85 ground wire is the ground at all times, so there would be potential voltage at the fuel pump relay. The blown diode would allow the voltage potential to find the least resistant path to ground however, which would be the starter solenoid windings.

asiab3 wrote: EDIT: and if the starter circuit DID get activated, wouldn't the starter temporarily turned into a generator, but with no output because the solenoid is interrupting any current? Would that melt some wires too?

If the starter did get *engaged to the flywheel*, that means the solenoid has engaged the motor-to-bat terminals inside the solenoid with that big copper plunger. The starter would indeed be an engine generator that fed electricity to the battery through the motor-to- 30 terminals on the starter solenoid. I guarantee you it would be a very unhappy 15,000-30,000 rpm generator.

Last night coming home (1AM) late my Westy was having troubles, mis-firing and lack of power but I got home. Changed out the CHT for a spare and starting cleaning the contacts in the double relay. I noticed the double red wires were loose and not seated all the way. Tightened the terminal , cleaned it and re-installed it. Test drove it and everything is fine again.
That was a easy fix but last night I was really wondering what it could be. Time to go thru the electrical FI harness again checking for tight connections as its the original harness.

Bleyseng wrote:Last night coming home (1AM) late my Westy was having troubles, mis-firing and lack of power but I got home. Changed out the CHT for a spare and starting cleaning the contacts in the double relay. I noticed the double red wires were loose and not seated all the way. Tightened the terminal , cleaned it and re-installed it. Test drove it and everything is fine again.
That was a easy fix but last night I was really wondering what it could be. Time to go thru the electrical FI harness again checking for tight connections as its the original harness.

Most of our running ills with fuel injection can be attributed to loose connections/wires especially the 85 brown ground wires trapped at the double relay mounting screw.

What led you to go in and clean the contacts inside the relay? That seems like an advanced go-to place . . .
Colin