Itinerant Air-Cooled

I'm still trying to build data on this, but it's happened 3 times - so it's a trend, right? We're rolling along fine at around 30 mph in 3rd or 4th gear, not accelerating. RPMs start dropping until the bus stalls. Coast to a stop, turn the ignition off, and it re-lights and operates normally. I don't know if it would restart without turning the ignition off, Mike or I will try that next time it happens. It's not like an immediate shutoff, I would describe it as 'running down' to the point of stalling. Feathering the throttle doesn't change the situation, it's going all the way down. We don't observe any other problems before or after these events.

First thing I will do will be clean and dielectric grease all the grounds. What else does the collective wisdom feel we should be looking at?

Dang I had a huge response typed up then my hotel wifi kicked me off and I lost it.

Air/Fuel - Spark - Compression. What tests have you done recently to any of those systems?

I personally ignore compression until proven guilty. Have you checked fuel pressure, filter cleanliness, injector grounds (yes, good,) or the condition of the muck in the gas tank? If you can get a strobe timing light on it, does the light flash when the engine is dying? That tells me if spark is firing.

You sure your knee isn't bumping the key to the "off" position?

Oh wait these are Volkswagens,
Robbie

asiab3 wrote:Dang I had a huge response typed up then my hotel wifi kicked me off and I lost it.

Hate it when that happens, and it happens all the time!

Air/Fuel - Spark - Compression. What tests have you done recently to any of those systems?

Air/Fuel/Spark all checked on Colin's visit 8/15. Did not check the compression, but it's running strong when it is running.

Have you checked fuel pressure, filter cleanliness, injector grounds (yes, good,) or the condition of the muck in the gas tank?

Have not but will. It doesn't act like a fuel flow restriction because it runs fine when accelerating or hill climbing. It's transient so it could be a lack of fuel pressure though.

does the light flash when the engine is dying? That tells me if spark is firing.

It's happened 3 times at road speed in maybe 60 miles of driving, and is unpredictable. I need it to fail a little more regularly before we can get two people and try this.

You sure your knee isn't bumping the key to the "off" position?

This would be TOTALLY possible if it was me driving, but it's happened to my son Michael too and he's not got the human factors issues I do.

Oh wait these are Volkswagens,

And 40 year old ones at that.

jcbrock wrote:

asiab3 wrote:Dang I had a huge response typed up then my hotel wifi kicked me off and I lost it.

Hate it when that happens, and it happens all the time!

Air/Fuel - Spark - Compression. What tests have you done recently to any of those systems?

Air/Fuel/Spark all checked on Colin's visit 8/15. Did not check the compression, but it's running strong when it is running.

Have you checked fuel pressure, filter cleanliness, injector grounds (yes, good,) or the condition of the muck in the gas tank?

Have not but will. It doesn't act like a fuel flow restriction because it runs fine when accelerating or hill climbing. It's transient so it could be a lack of fuel pressure though.

does the light flash when the engine is dying? That tells me if spark is firing.

It's happened 3 times at road speed in maybe 60 miles of driving, and is unpredictable. I need it to fail a little more regularly before we can get two people and try this.

You sure your knee isn't bumping the key to the "off" position?

This would be TOTALLY possible if it was me driving, but it's happened to my son Michael too and he's not got the human factors issues I do.

Oh wait these are Volkswagens,

And 40 year old ones at that.

Don't kick old Volkswagens . . . I just had to diagnose a LT-1 Corvette with a bad "optispark distributor" or whatever. It is located under the water pump and behind the crankshaft pulley. If the water pump weeps, zowzapoof! new distributor too! Removing the distributor on these engines requires removing the air duct and serpentine belt, then the water pump, then the crankshaft pulley and damper, then the belt tensioner, and finally the three bolts that attach the Opti-Spark distributor to the front timing cover. Good gawd.

So, your symptoms sound like the engine is quitting. Next time, push in the clutch right away and see if the engine dies dead instead of continuing to rotate and clatter because of vehicle momentum. This will help you determine if this is a soft failure versus a hard failure. Hard failures are usually ignition/electrical, soft failures are usually fuel-related. Keep an eye on your black wire from the coil to the inline fuse on the left that feeds the reverse circuit. There is another wire that branches out upstream of the fuse itself. That wire feeds the double relay. If the reverse fuse holder (holder clip) shorts, it kills the fuel pump. This can be intermittent.
Colin

asiab3 wrote: You sure your knee isn't bumping the key to the "off" position?
Oh wait these are Volkswagens,

Meaning, these are quality cars, given more design attention than the New American Ignition Switch Blunders.

asiab3 wrote:

asiab3 wrote: You sure your knee isn't bumping the key to the "off" position?
Oh wait these are Volkswagens,

Meaning, these are quality cars, given more design attention than the New American Ignition Switch Blunders.

Oh true that . . . and the late model VW buses have the dorkiest ignition switch position ever to avoid any knee-bump.
Colin

Just reporting in, it's been a month and no recurrence yet. I went for a 40 mile drive last night, so it is just going to happen sometime when it is most inconvenient. I guess it's possible driving the car has knocked some corrosion off some contacts or some such self-repair, but I'm not counting on it!

jcbrock wrote:Just reporting in, it's been a month and no recurrence yet. I went for a 40 mile drive last night, so it is just going to happen sometime when it is most inconvenient. I guess it's possible driving the car has knocked some corrosion off some contacts or some such self-repair, but I'm not counting on it!

Thank-you for the update. It is only going to happen again at an inconvenient time if the Universe needs to punish your lack of faith . . .