No start - I've got spark, I've got fuel, but that's it

[VicVan]

Howdy

1990 Westfalia, 2WD auto, stock

engine cranks fine, hardly bucks, and doesn't start.

What I've done so far:
Battery
Battery is charged. 12.8V when charged, after some rest (I have not checked battry voltage drop while cranking).
Spark
- good spark out of the main wire from the coil (the one that plugs in the rotor)
- Cleaned the rotor and the contacts (the thing is 2 years / 10 000 km old and in good shape)
- I've checked for spark at cylinders 2, 3 and 4 using an alternate spark plug (just unplugging the connector). Spark every time.
I could check with the actual spark plugs, they are 2 years old, NGK I believe.
Air
- Checked air filter, is very clean. Unplugged the hose from the snorkel, so air comes directly to the air filter box, just in case the snorkel was plugged. AFM rotating door thing moves freely.
Fuel
- Checked spray pattern of driver's side cylinders (3 and 4). Looked good, cone shaped. Injectors professionally cleaned 3 years / 15 000 km ago.
- Cleaned pre-pump filter (added by myself)
- Cleaned fuel pump, found a lot of rust dust and flakes.
- Changed post-pump fuel filter.
- Borrowed a fuel pressure test kit: 35 psi at the T, as per Bentley (pressure is likely above that value, the gaue fitting started to leak so I turned off the fuel pump - I'll do another test tomorrow with a more secure install. Should be closer to 40 psi).
- Fuel level was on the lower side, so I added 20L (5 gallons) just to be sure.

I'm stumped. Tomorrow I'll check for spark properly, and redo a fuel pressure test. Is there another obvious culprit that I'm forgetting?



Note that for all these tests I've been using crazyvwvanman's bypassing tool. In short, it powers ECU. coil and Fuel pump directly from the battery, bypassing all the circuitry (ignition switch, neutral safety switch, etc)

Not sure if it's relevant, but I've noticed that for the last few months, if I failed to start it the first time (releasing the key too soon), it was much more difficult to start the second time.
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'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)

[Wildthings]

What repairs have you done to your engine and electrical recently?

[VicVan]

[Abscate]

Give it a sniff of ether and see if you get some fire.

That will separate the ignition from the fuel diagnostic tree
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.ssS!

[crazyvwvanman]

Another test to try. Open the engine lid and leave off.
Crank it over a few times to try to start it.
If no start, quickly run back and unplug all 4 injector connectors from the injectors and leave them off.
Quickly try to start the engine again a few times. Does it briefly start or sound more like it might?
Quickly try a few more starts, this time pushing the gas pedal slightly with your foot.

----------------
Starting fluid is good to tell you if you aren't getting enough fuel but won't tell you much if the problem is too much fuel.
Known failure mode of 2.1 ECU is too much fuel flooding the intake.

Edit: I should also mention that your previous clue of being harder to start on subsequent tries also points to a possible flooding condition. If the problem is the ECU then this symptom could be made worse when the test bypass harness is fully plugged in since the ECU and the injectors will have constant power and the fuel pump will be running. Different years of Digifant harness would be affected slightly differently with this ECU flooding failure mode.

Mark

[MarkWard]

Assuming the injectors are spraying, the engine must start on the first attempt. If it doesn’t, additional attempts will flood the engine. Eventually washing the rings enough to loose compression.

So, you need to figure out why it doesn’t start on the first attempt. If it’s over fueling, as suggested, introducing a large vacuum leak might improve starting. Remove one of the large hoses from the intake boot. This will introduce air without increasing fuel demand. It’s just a way to pinpoint where to look.
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[VicVan]

I'll try Marks's injector test tonight. I'll plug back the stock wiring too.
I also have a spare ECU too, so I'll test it as well.
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'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)

[VicVan]

So... I tried to do Mark's test, and upon step 2 (injectors unplugged), the starter died.



What the hell?

Battery measures 12.7 V, drops at 12.4 when I'm trying to start (with the starter not cranking that is).

Ideas: the engine ground (left side on the engine bay) looks slightly corroded, maybe I could change that.
Should I have the battery tested just to make sure?
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'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)

[Howesight]

I will not comment on the starter problem, but on the no-start problem before your starter went south, I suggest that you check to ensure:

1. Your distributor rotor is fully and properly seated on the distributor shaft;
2. The distributor shaft is properly seated in the distributor drive.

I agree with the comments above concerning a possible fuel flooding problem. Remove the spark plugs after your next attempt to start to see if the spark plugs are wet with fuel. If so, leave them out and, with the injector electrical connectors unplugged, operate the starter with the throttle fully opened to clear the excess fuel out. And do replace that ground strap.

Hope this helps!
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'86 Syncro Westy SVX

[DanHoug]

Time to go old school .... put a NEW set of plugs in and try it. Doesn’t matter how recently they’ve been changed. Put a new set in and crank it.
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-dan
60% of what you find on the internet is wrong, including this post.

'87 Westy & '89 Westy both 2.1 4spd

Past projects can be found at--
www.thefixitworkshop.com

[davideric9]

I've had this problem. Mine was resolved with new Temp II sensor. I was able to check this with a spare known good sensor, plugged it into the connector without installing it, and the van started right up. Also easy to check the sensor with VO meter. Check the easy stuff first before throwing parts at it, like the throttle position switch, idle control components. Meter the digifant sensors where you can. Good luck.
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1987 Syncro Westfalia, stock (bought 1994)
1986 Syncro Westfalia SVX, 3 knob (bought 2008)
1987 Westfalia (bought 2010)
1988 Wolfsburg GL (bought 2012)

[MarkWard]

[VicVan]

[VicVan]

[VicVan]

Just received the adapter plate. Overnight shiiping from Werk1, shoutout to Barry and to CanadaPost! (Well, they're not that far from me, but still). I'll get going on the starter tonight or tomorrow.

Thinking ahead: if further diagnostics point to a failed ECU, how safe is it to plug a fresh one in? I don't wan't the new to fry as soon as I plug it in...
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'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)

[MarkWard]

Disable the alternator while you test. That will avoid a voltage spike. If you are considering it’s the ECU, you’ve already verified the wiring is correct and not shorted. So, you should be fine.
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[VicVan]

[felixbobcat]

When I installed my engine it did the same thing. Cranked but would not start.

Plug wires were out of order. You might want to see if you timing is off also. That could create the same problem.

[VicVan]

[VicVan]

Well, I've replaced the starter (Second hand SR0408X with TDI adapter).
(I've also replaced the engine ground on the left side, it was actually in pretty good shape. What I mistook for crud and corrosion was in fact dirty copper! Can't hurt anyway.)

The starter turned, the engine cranked... and started! To my big surprise, I would say. I was expecting the same symptoms than before the starter died, that is cranking but not starting.

Well, it must have been something I've done, cause know it works. I've started cold a couple of times, let it heat up a bit, and tried a couple of hot starts; started right away each time

To sum up, I've
- cleaned all grounds (but they seemed in good shape, there was still some dielectrical grease from last time, and no corrosion whatsoever)
- Replaced the battery
- cleaned fuel filters and fuel pump
- changed the starter

We'll see in the next few days if it still starts. Thanks again for your help. I've learned some cool stuff.
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'90 Little Blue Truck, 2WD auto, FAS GenV 2.0 NA (AVH)