TheSamba.com Forums
 
  View original topic: No start - I've got spark, I've got fuel, but that's it
VicVan Sun Oct 18, 2020 8:23 pm

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.

Wildthings Sun Oct 18, 2020 9:26 pm

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

VicVan Sun Oct 18, 2020 10:25 pm

Wildthings wrote: What repairs have you done to your engine and electrical recently?
Right before it stopped working, nothing at all.
Last work done was
- water pump replacement by the garage, 2 months/2000 km ago
- power door lock actuator, pax side, 1 month 1/2 ago

Abscate Mon Oct 19, 2020 3:22 am

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

That will separate the ignition from the fuel diagnostic tree

crazyvwvanman Mon Oct 19, 2020 3:47 am

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 Mon Oct 19, 2020 7:15 am

Assuming the injectors are spraying, the engine must start on the first attempt. If it doesnít, additional attempts will flood the engine. Eventually washing the rings enough to loose compression.

So, you need to figure out why it doesnít start on the first attempt. If itís 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. Itís just a way to pinpoint where to look.

VicVan Mon Oct 19, 2020 2:43 pm

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.

VicVan Mon Oct 19, 2020 10:34 pm

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

:shock:

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?

Howesight Mon Oct 19, 2020 10:59 pm

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!

DanHoug Tue Oct 20, 2020 6:34 pm

Time to go old school .... put a NEW set of plugs in and try it. Doesnít matter how recently theyíve been changed. Put a new set in and crank it.

davideric9 Wed Oct 21, 2020 9:11 am

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.

MarkWard Wed Oct 21, 2020 9:42 am

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

:shock:

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?

Can you turn it though by hand? Last van I worked on had cylinders full of raw fuel that hydro locked the engine.

Or it's just coinicidence and the starter has been getting a work out if the van is not starting.

VicVan Wed Oct 21, 2020 10:29 am

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

:shock:

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?

Can you turn it though by hand? Last van I worked on had cylinders full of raw fuel that hydro locked the engine.

Or it's just coinicidence and the starter has been getting a work out if the van is not starting.

Hmm, good point. I'll try that tonight.
In the meantine I've checked the grounds at the transmission and the battery. They were fine, I cleaned and greased them anyway.
I do have battery voltage at the ignition wire connector on the solenoid, indicaitng that the current does get from the battery to the ignotion switch to the starter solenoid).
I've had the battery tested, it did not pass. Not totally dead, but I bought a new one. I've also bought a remote ignition switch to make my life easier.

So tonight, we'll be having
1/ Install new battery
2/ Test starter with remote ignition switch
If this fails, I need a new starter.
3/ Test turning the engine by hand. If it doesn't, remove spark plugs and blow air in the cylinders.

I'll keep you posted!

VicVan Thu Oct 22, 2020 9:46 pm

VicVan wrote:
1/ Install new battery
2/ Test starter with remote ignition switch
If this fails, I need a new starter.
3/ Test turning the engine by hand. If it doesn't, remove spark plugs and blow air in the cylinders.

New battery in place. Remote ignition switch in place, nothing happened. Not even a click from the solenoid.
And the engine does turn by hand.

After some forum reading yesterday night, I opted for the TDI starter + adapter plate. I ordered the adapter plate and harness adapter from Werke1 in Vancouver, and found a used Bosch starter from a 2000something Jetta (TDI, manual). Barry @ Werke1 also told me that starters for 1.8T work too. Reference Bosch SR0425N

Hopefully I get these by the weekend and can get crackin' (or crankin').

:wink:

VicVan Fri Oct 23, 2020 4:25 pm

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...

MarkWard Fri Oct 23, 2020 4:34 pm

Disable the alternator while you test. That will avoid a voltage spike. If you are considering itís the ECU, youíve already verified the wiring is correct and not shorted. So, you should be fine.

VicVan Fri Oct 23, 2020 7:39 pm

MarkWard wrote: youíve already verified the wiring is correct and not shorted.
Are you talking about these tests?


felixbobcat Sat Oct 24, 2020 10:43 am

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 Sat Oct 24, 2020 2:02 pm

felixbobcat wrote: 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.
I did check, just for peac of mind. But the truth is it ran fine the last time, and I haven't touched the enigne since. It doesn't even buck or anything.

I'm in the process of replacing the starter, so we'll see soon enough!

VicVan Sun Oct 25, 2020 9:58 pm

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! :shock: 8) 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 :D

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.



Powered by phpBB © 2001, 2005 phpBB Group