1990 Volkswagen Transporter injector problem

If you have one injector that is staying on and not pulsing, the the ground trigger wire is shorted to ground. That could be in the wiring or the PCM itself. The wiring will have to be tested to find out.

All Injectors fire at the same time.

Remove the injectors from the intake runners and cycle the key on / off with the injectors harness plugs
disconnected. If #3 cyl is leaking fuel, replace it.

If the Injectors do not leak, re-connect the harness plugs and crank the engine (disconnect the coil wire from
the distributor cap and ground it). All Injectors should pulse.

If #3 looks to be spraying all the time, rather than pulse, replace the #3 injector.

Thomas

Or you could just check the injector commands and wiring as advised before taking the injector rail all apart.

I'm not stepping on your toes or saying my advice is better. As with all my replies (to VW / Audi Topics) I tend to speak from experience.

I'm sure you know what a rail looks like on a boxer engine. And how time consuming it is to remove 2 bolts to take out 4 injectors.

20+ years in the VW field. I have yet to see a wiring harness issue, or a bad ECM.

Thomas

I would think it is just common sense to first determine if the problem is electrical or mechanical before disturbing and possibly damaging injector seals and O-rings for no reason. Something as simple as just unplugging the offending injector should answer that question.

He's already done that.