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dead coil? I need convincing
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Bambus
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PostPosted: Sat Jun 16, 2007 8:57 pm    Post subject: dead coil? I need convincing Reply with quote

Hola, group.

Situation and establishing backstory: i grounded my van ('85) around New Year's to finally fix the trashed fuel tank condition. Van could run well up until its lay-up, but would foul fuel filters really quickly, to the point that i always travel with at least 2 spare filters at all times. By the time it became completely unreliable (ie having to change filters in parking lots in the winter rain) i just resolved to park it and get to it when i could. I KNEW there was a ton of garbage in the tank (water globules, rust colored gas/SeaFoam/Stabil mix, and large nuggets of rust would come out of the supply side of the filters when emptied into a clean test container), so just let it sit until a couple of weeks ago.

Tank cleaning went as well as one can do in the driveway. By the time i was done sloshing 2 lengths of steel chain (agitators) and a gallon can of WD40, the inside was decently (and relatively) clean. New grommets, new sender o-ring, new vent rubber all around. During removal of all tank components, I did notice that the grommet that seals the top of the left side plastic expansion tank vent valve (left fender well) was disintegrated, leaving a gaping hole in the top of the plastic tank-- said vent tank had much sand, red clay and other dirt inside. Guess this is how i was getting water into the fuel after driving in rain. (at least THAT mystery was solved, at long last)

Wanted to clean and test the rest of the fuel circuit while i was at it, and renew all the fuel line. Removed pump and ran it on a test-bench rig i made: i did'nt have any means to grade the output flow rate, but it was *very* vigorous and rapid. Seems like it was running through a gallon in about a minute or so. Seemed healthy compared to other Bosch pumps i've tested

Injectors were given 12V on the bench while listening for the solenoid clicks-- seem good. Renewed all injector seals to manifold.

Blew through both supply and return lines (disconnected from regulator) from the engine room up to the tank fittings with comp air-- all clear there.

Oh and i replaced all the wee vac lines and clamped any others that moved easily.

Set TPS

Pulled Hall controller from the bulkhead and cleaned it and the heatsink, applied a thin smear of 3M Silicone paste tween module and sink

Inst new O2 sensor

Cleaned inside of dist cap (much pitting, will replace it and rotor this week), and wirebrushed the tip of the rotor. Cap button OK

New airfilter (hella overdue, by years), replacing the barely fitting no-name flopper that was in there with good Mahle

Batt was flat after 5.5 months of sitting, so charged overnight-- highest charge i got was 12.6. The batt is still toast (drops below 11V when a load-tester is applied), so i used another vehicle to jump.

So it would seem i'm a thorough wrench. I methodically covered fuel delivery, cleanliness, TPS, injector function, and vac leaks. I rationalized that anything else would still be in the ballpark/functional state that existed when last the bus ran.

clutch in, and i start cranking with the jump car idling. Slow (normal) spinning, but not the slightest hint of spark. Repeat cranking cycles. Nada. I recheck everything that had been touched in all my ops. Rinse, wash, repeat. By now i *know* i'm not sparking, just injecting more gas into the cylinders.

I pull #3 plug to see what's up-- wet with fuel. So i knew i had fuel to at least #3, and no reason to think any delivery issues exist anywhere else.

I knew i had compression (remember, the van's sole prior issue was shitty gas; it ran in decent ballpark tune prior to being parked in January), and i had no reason to suspect an all-of-a-sudden ignition fault.

I was tired and frustrated at this point (6 hours straight today, in the sun, natch), but i pressed on with the Bentley and my VOM to check the ignition syst.

What i found: (jump car disconnected for this and all subsequent tests (duh))

Hall:
checked Hall unit plug V between pins 2 and 4 = key-on and i got nearly batt V, as per Bentley.

Coil:
Primary R, with VOM on term 1 (-) and term 15 (+) = immediate continuity, setting my meter's continuity beep off instantly. Spec is *supposed* to be .420-.760 Ohm

Secondary R, with VOM on term 1 (-) and term 4 (center post) = 1428 Ohm. Spec is *supposed* to be 2400-3500 Ohms.

Clearly this coil is outside of spec on both Primary and secondary. I just find this very difficult to believe! The coil *could* have been marginal when last the bus ran, but this just seems so damned fishy. And i absolutely HATE throwing parts at a problem-- esp when i know how to do diagnostics.

For shits and giggles i reconnected everything, hooked my jump car back up, and installed a pressure gauge on the fuel rail Tee and cranked again. The gauge showed 90 PSi! But i don't know if that's significant since the normal pressure tests (reg vac on and off) are done at idle, which of course i can't do because i can't crank in the first place!!

I ran out of daylight (and personal steam) today but i plan on checking temp II resistance tomorrow-- something that needs to be done as part of a thorough check but is certainly outside of the coil issue.

So: Have i reasonably identified a dead coil? Or is more detective work necessary here? Go back to what i said about the batt: it's a goner, but is it possible that it's SO gone that even with a jump vehicle it's causing dead-coil symptoms? This does'nt seem likely, as the coil was of course completely disconnected for the VOM tests i did. Could all of my cranking attempts have pushed a marginal coil to the Great Beyond?

I don't mind springing for a new coil, and yes i'd click my heels if that were the only issue. This just does'nt seem that simple. Coincidences happen in electrics all the time, but i still don't easily believe in such magical coincidence.

Need some group energy here!

Best,
MRP
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Terry Kay
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PostPosted: Sun Jun 17, 2007 10:17 am    Post subject: Reply with quote

The Van needs proper volts for the engine electronics to operate.

if you have short voltage even though your jumping it it may not be enough.
The old battery is sucking up the majority of it.

But, do this;

If you have a remote starter button hook it up to the starter.
If you do't have a remote starter button , get someone to do the ignition switch work in the Van.
Hook up the donor voltage vehicle.

Remove the coil wire from the cap and hold it a 1/16th, to an 1/8th of an inch from the engine block.

Crank the engine over.

If you get a blue zap in the air gap between the wire and the engine, the coil is throwing spark.

You spent waaay too much time diagnosing the coil.
This proceedure would have told you the whole story a bunch faster.

If you have spark at the coil, the cap/ rotor are shot, or the pick up in the distributor isn't working--

Pretty common for an older Vanagon.

Get a new battery, tune the Van up,and check out the pick up in the distributor.

Also check out the power supply relay.
It supplies the juice to the ECU.
if this isn't working--your not going to be getting the engine running.

Take a look at the idle stabilizer on your 85.
Dissconnect it, take the 2 plugs and connect them together.
If the Van starts, here was the problem.
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tencentlife
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PostPosted: Sun Jun 17, 2007 5:36 pm    Post subject: Reply with quote

The problem is staring you in the face: 90psi on the fuel rail is very significant. That's going to totally flood the motor. I doubt any of the plugs even got a chance to throw a single spark before they got hosed down with liquid gas.

The highest pressure you should ever see on the rail is 36psi, and it gets modulated down to 29 under high manifold vacuum. The motor doesn't need to be running to check the basic rail pressure, though. You only need the engine idling to see how the regulator modulates for idling and cruising, and you can even check that with a hand vacuum pump if you want.

You've either got a bad regulator, or you've mis-plumbed the fuel lines in the engine bay. I would guess the regulator had gotten dirty before and now it is stuck closed after sitting so long.

If you have enough voltage to crank the engine at a decent speed, and the pump puts out that kind of pressure, then you've got enough voltage in the FI system. The pump and ignition will operate well enough to start with as little as 10 volts delivered. If you want to be sure, let your jumper car run awhile to let your van's battery get a deeper charge. But the fact that your pump runs (rather well, I'd say) and your injectors open, proves that the main power bus for the FI and ignition controls are getting high enough voltage to start.

Do TK's basic spark test by arcing the coil center lead, so you know your coil is making good spark, and you can move on. But your real problem is that way-too-high fuel pressure.
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Terry Kay
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PostPosted: Sun Jun 17, 2007 7:35 pm    Post subject: Reply with quote

Oh Boy---

Did I miss that call--

At 90 pounds fuel pressure he's got fire hose nozzle's pumping into the cylinder's.

Splish splash,the plugs are taking a bath--
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Alan Brase
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PostPosted: Mon Jun 18, 2007 5:21 am    Post subject: Reply with quote

Terry Kay wrote:
Oh Boy---


Splish splash,the plugs are taking a bath--

And now they are too wet to spark, probably need to pull them out and dry off with compressed air.
Perhaps a squirt of oil in each spark plug hole and a quick spin of the engine..
Whenever you do things like this, it is a good idea to either take the primary coil wire off or ground the secondary coil wire, or unplug the distriubtor. This will stop any errant sparks that might make this gas-bobmb ignite.
Double check the plumbing thru the pressure regulator. but I have found the pressure regulator to be the least reliable piece of the whole system.
Al
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Bambus
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PostPosted: Mon Jun 18, 2007 5:35 am    Post subject: Reply with quote

thanks folks--

somewhere in the last 15 years i picked up the errant idea that one should'nt do the traditional hold-the-coil-lead-to-ground spark test on electronic ign vehicles-- if i'd known that was OK i woulda done that right off.

Press reg: guess that mug's sticking out sore thumb style eh?

Thanks again, now i can start throwing parts at it with high accuracy. Idea

MRP
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PostPosted: Mon Jun 18, 2007 5:54 am    Post subject: Reply with quote

damn, just did a lookup on a new regulator = $100

any track record of trying to resurrect a sticky one by soaking in PB etc?
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tencentlife
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PostPosted: Mon Jun 18, 2007 7:10 am    Post subject: Reply with quote

I took one apart once and welded it up to be adjustable. That was back when they cost $35. It's still around here somewhere. Worked pretty good, too, but changing the pressure didn't do much for power.

It does seem like yours has to be glued shut internally, so who knows what might happen if you get some solvent in there? Laying it on its back and putting solvent into the return line fitting would get the solvent to the regulation port the best, I would think. It has to be that, or total blockage in the fuel return pipe, but you said you blew that out. You could go over and bark up that tree again just to be absolutely sure. Shoot some air up the line with the gas cap off, have someone listen for bubbling in the tank. Or install a tee in place of the regulator and test pressure again; it should be very very low in that scenario, and spike high if you pinch off the return line.

You do know that you can jumper the fuel pump safely to test the supply system, don't you? Make a little jumper with two male spades, remove the fuel pump relay (right side relay in the relay box on the left wall of the engine bay). With standard relays, the two pins that make a letter "T" to each other are the #30 and #87 pins that the relay connects when it is triggered, so if you bridge those pins you'll switch on whatever the relay powers.

As I mentioned above, you can also run the pump and fake the high vacuum signal to the reg with a hand vac pump. About 12 or more inches Hg applied to the reg's vacuum port should lower the pressure to 29psi, otherwise it should be 36psi, never higher than that.
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PostPosted: Mon Jun 18, 2007 8:06 pm    Post subject: UPDATE + junkyard day Reply with quote

So it's kind of obvious by now that i have a gone-south PressReg. Just to cover bases i enlisted a helper this morn to crank while i held the coil lead to a fresh, shiny ground on the big steel AC compressor bracket. Sparks galore. So, with a grin, i can remove the coil from the suspect list. (NOW tell me where i got the old-wives-tale BS about not cranking an electronic-ign vehicle with the coil lead pulled-- did i just conflate other warnings about electronic ign?? On points cars -- like my old '81 van-- that kind of coil test was one of the first things i would do, in this case i erred on the side of caution that came from _somewhere_)

Anyway, spent today rummaging around the local junkyards looking for a WBX pressure reg. No dice, but i did find an '82 camper with a damned straight body-- i've filed that one away as a future source of sheetmetal, glass, etc.

Heartbreak of the day? Went last to a very old salvage yard and asked if they had any Vanagons-- the lady looks up at me in disbelief: "Well we did until 2 weeks ago! We just had it crushed-- we had that thing for years and nobody ever bought a damned thing off of it."

Yep, timing is everything. Apparently it was an '86, straight body, just had a dead engine (we've all seen/heard that a time or two, yeah?). Damn. Mad Oh, the useful things i could have taken from that one...

Our excellent foreign parts FLAPS here can get me a genuine Bosch reg overnight, at a few $$ less than mail order from our usual online suspects. I'm going that route and will keep scouring the junkyards for spares.

Something i'd forgotten is just how fun and weird junkyards are. Lots of treasures, and they are *complete* toxic waste dumps! The smell of a salvage yard is unmistakable: that super-sweet candied Old Gasoline smell, mixed w/ ATF and anti-freeze. And rotting tires.

Thanks for all the help here, mangs

Best,

MRP
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PostPosted: Mon Jun 18, 2007 9:08 pm    Post subject: Reply with quote

I've had a press regulator crap out where it was worn out in the wide open mode. I had a mix so rich the extra gas was staying in the cylinders long enough to get past the rings and foul the oil. The oil level would rise (and thin) and I got a really impressive cloud out the back. It looked like the county mosquito truck and the oil buzzer was screaming at the same time. Never pulled off the road so fast in my life.

Seems to me that a pressure regulator (even $100 new) is not something I'd get from a junk yard. A fender sure but a part that needs a rubber diaphragm to control high pressure gasoline seems like something that would be pre-broken before I pulled it off a wreck. Maybe I'm just used to midwest yards that only have 2 jettas and half a bug pan in the "VW" section.
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PostPosted: Tue Jun 19, 2007 8:13 am    Post subject: Reply with quote

Quote:
I've had a press regulator crap out where it was worn out in the wide open mode.


Not to nitpick, but yours was stuck in the closed mode, as is Bambus'. Wide open would let all the pressure out.

I'm not going to rewrite it, but somewhere awhile back I wrote up a detailed description of how this amazingly simple device works. Maybe do a search if you're curious.

Quote:
(NOW tell me where i got the old-wives-tale BS about not cranking an electronic-ign vehicle with the coil lead pulled-- did i just conflate other warnings about electronic ign??


As long as you let the energy ground out, by holding the high-tension lead to the block or the chassis, it's OK to test an electronic ignition this way. It was Capacitive Discharge ignitions, like used on some Porsches, that were sensitive to this kind of testing, that's probably what you're conflating this with, but even with them you could test as long as you let the spark jump to ground. The problem with the CD units was the incredible voltage it would run at; it was hard to safely isolate yourself from it while testing, and it could sure give your own ticker a dangerous jolt. But as long as the voltage is allowed to dissipate in the normal cycle, the system shouldn't really care whether it was routed thru the distributor or went directly to ground, at least for a brief test.

Don't get me going about salvage yards (out of respect for my friendly local wrecker, I'm refraining from calling it a junkyard). I show up at DAP in 'Burque, and Trey just lets me wander in the back and rummage around at will. He knows that if I came for one item, I'll mosey back in an hour later with as much as I can carry, picking up all kinds of little bits that I didn't think I needed, but suddenly can't live without. It's good for business; he looks at my armload of stuff, and says "just give me $X", and off I go, very pleased with myself. I've always been a junkyard junkie.
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Alan Brase
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PostPosted: Tue Jun 19, 2007 8:37 am    Post subject: Reply with quote

tencentlife wrote:

Quote:
(NOW tell me where i got the old-wives-tale BS about not cranking an electronic-ign vehicle with the coil lead pulled-- did i just conflate other warnings about electronic ign??

The problem with the CD units was the incredible voltage it would run at; it was hard to safely isolate yourself from it while testing, and it could sure give your own ticker a dangerous jolt.

I think even the primary voltage gets pretty high. Hence the Deutsch tem "ACHTUNG!"

Quote:

Don't get me going about salvage yards (out of respect for my friendly local wrecker, I'm refraining from calling it a junkyard). I show up at DAP in 'Burque, and Trey just lets me wander in the back and rummage around at will. He knows that if I came for one item, I'll mosey back in an hour later with as much as I can carry, picking up all kinds of little bits that I didn't think I needed, but suddenly can't live without. It's good for business; he looks at my armload of stuff, and says "just give me $X", and off I go, very pleased with myself. I've always been a junkyard junkie.

Yes, there is probably a 12 step program for us.
Al
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tencentlife
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PostPosted: Tue Jun 19, 2007 9:08 am    Post subject: Reply with quote

Well, it's about 12 steps from one wrecked van to the next, so I guess I'm already with the program!
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PostPosted: Wed Jun 20, 2007 10:26 pm    Post subject: Reply with quote

yo tenny-cent: since you've split a pressure regulator to see the internals, school me on how exactly these operate internally. By peering into my crapped out reg, i see a spring-loaded shaft. Of course there's a diaphragm in there, but is the reg essentially a valve that utilizes vac to move a piston back and forth to make an orifice (the inlet/outlet side tubes) smaller and larger, thus varying pressure with an opening that gets smaller (higher pressure) and larger (lower pressure)??? (i'm thinking Bernoulli here)

I want to understand the ops of this 100$ piece!

BTW: got my new reg today, will inst tmw-- new parts are always sweet, but i'm keen on seeeing if i can resurrect my old sticky one (it's been soaking in min spirits for 2 days)

MRP
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PostPosted: Wed Jun 20, 2007 10:45 pm    Post subject: Reply with quote

No Bernoulli stuff happening, just fuel pressure and spring pressure in balance. Here's the best I could do with it:

http://www.thesamba.com/vw/forum/viewtopic.php?t=2...p;start=20
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PostPosted: Thu Jun 21, 2007 12:29 am    Post subject: Reply with quote

read it, got it. Thanks king. Your supply of promised beers must be growing huge by now. Add mine in.

MRP

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PostPosted: Thu Jun 21, 2007 4:39 am    Post subject: Reply with quote

Quote:
I'm not going to rewrite it, but somewhere awhile back I wrote up a detailed description of how this amazingly simple device works. Maybe do a search if you're curious.


Yea TENCENTLIFE, that was a post I had started towards the end of last year, when I descovered that the vacuum line on my fuel pressure regulator was missing. I had no power above 50 MPH. As soon as I connected a vacuum line to it, it was as though a new engine had been installed. It was a great write up then, and should have been placed in the stickies, with all the other good writeups you've put forth.
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PostPosted: Thu Jun 21, 2007 6:34 am    Post subject: Reply with quote

It seems that tencentlife is always deserving of a stickie, bud.

Many thanks!
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PostPosted: Fri Jun 22, 2007 6:50 am    Post subject: Reply with quote

Glad it helped.

Sticky, bud, is always welcome.
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