2.1 WBX (SR) Starting Problems (Bad ECU?)

[tjet]

A compression test will rule out mechanical damage

[tjet]

[tvavrda]

Got it. Will do a compression test.

[tvavrda]

Still thinking if a mechanical problem would only appear when running on petrol but not on LP? Maybe because LP is slightly hotter?

[tvavrda]

[tjet]

Your past and current starting issues are tell-tale signs of a post-hydrolock event.

Hopefully, I'm wrong and thats not the case...

[DanHoug]

to me the smoking gun is that it runs fine on LPG. so you have a fuel issue and i'd wager that with all the work you've done on the fuel system you have plugged injectors or more specifically, plugged inlet screens on the inlet of each injector.

also, don't rule out low fuel pressure. i would absolutely do a fuel pressure test, which i haven't seen reference to yet. the injectors go from squirting a very nice combustible fog to merely a solid stream of gasoline when the pressure drops by not too much.
_________________
-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

[tvavrda]

I did complete fuel pressure test (pressure with/without vacuum, volume test, residual test). All within specs.

I visually checked injectors - they all work when cranking and seem to provide a nice cone of fuel...

After changing the tank I ran on top quality Shell petrol with additives. About 400 km on this without any issue. So I doubt the injectors would be clogged or something...

[tvavrda]

So IMHO there is spark, there is fuel, there is air... But it does not start... Must be a spark and fuel at wrong times or something? And this very bad sound sometimes... Or hesitating to crank on first turn sometimes...

Hesitation on first crank used to happen always when cranking after turning off the engine while running previously on LPG. Next time it cranked once... pause, and then it started. This was with the original starter with weared bushing. Since changing the starter this did not happen anymore, was starting immediately. Now it is back with all the other problems.

[DanHoug]

okay. good on checking for pressure and pattern. so the next thing that i would be curious to try is changing the ignition coil. the fuel/air mixture of LPG is somewhat easier to ignite than gasoline so it sorta makes sense it runs fine on LPG. this also meshes with starting issues and deteriorating performance after it has been running a while, as the coil can heat up and have high voltage breakdown. also, be somewhat suspect you have the right distributor cap and rotor. if the clearance is wrong, it can cause issues.

on that line of thought, make sure you have non-resistor plugs as you already have resistor plug wires. normally, they can fire with resistor plugs but if the coil is weak, it becomes an issue as there is usually a resistor in the rotor, then add in 5K on the wires and 5K on the plugs. can be too much.
_________________
-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

[tvavrda]

I have a new coil (again BOSCH - correct for my engine). Since the old one is a bit hard to remove (LPG stuff is nearby) I just made a small test by rewiring it to the new one. The results were the same, so I wired back the old one and left it for later.

I should have a good cap as it was assigned to my engine model in the catalog. Strangely, after putting it on it started on first crank. I thought I solved my starting issue but it was the only time it ran without a problem. Then it was again impossible to start (well one of 10-20 tries it also starts on 4 cylinders).

This happened again after cleaning AFM. It started to start very well! For about 5-10 times! And then again...

Anyway the old distributor cap was not bad, it just looks used but I ran on it since ever. I thought it would make things better so I replaced it but nothing changed. Old one/new one - same issue.

The plugs are new NGK B6ES. Again, the NGK product search shows these are correct plugs. Anyway, the old plugs had the same problem, they ran fine until now. When changed, the issue is still the same. Clearly, plugs were not the issue.

[tvavrda]

[DanHoug]

[tvavrda]

Thanks for all the efforts so far. I ordered the compression tester. Will test tomorrow.