DJ won't start

[jpennington]

Yesterday afternoon I fitted a new fuel filter. Yesterday evening I drove to the car wash. After the wash, it wouldn't start.
Pushed the van out of the wash bay, nothing obviously wrong, so called out the RAC.
RAC mechanic checked spark - good. Diagnosed failed fuel pump and towed me home.

Today I tested the pump - all good; flow 500cc in about 20 seconds.
But I couldn't hear the pump run at ignition on - normally it runs for about 2 seconds at switch on.

I've had that fault before - caused by a failure of the ignition control unit; pin 7 of the ICU provides an input to the ECU.
GSF no longer stock the ignition unit, so I popped up to Just Kampers.
With a new ICU the pump runs briefly at switch on, but the motor still won't start.

Any suggestions about what to do next?

BTW the plug on the wiring harness doesn't fit quite as tightly to the new ICU. ( Maybe I shouldn't have gone to JK, but it saved waiting a couple of days for the postman)

help!

[jpennington]

No suggestions?

Here's an update - more info but no answers.

Today - tested air flow meter - all working properly: resistance varies as the vane moves, fixed resistance is 560 ohms.
Checked all connections from the ECU - everything as it should be.
Pulled out one pair of injectors - no fuel spray when cranking.

So, it would seem that the fault is either in the ECU, the ICU or the Hall generator.
Tomorrow I plan to test the ICU, following the procedures in the VW Digijet Training Manual (most helpfully provided by a post on this site a few months ago).

I do so hope it's not the ECU!

jp

[dave friday]

check the fuel pump relay..maybe the energising coil is open circuit [there are two energising coils!!].
I had this happen on a 924 posche!!.

[jpennington]

Further update:

Dave Friday - thanks for suggestion; one of the ECU connection checks is to bridge two pins to make the fuel pump run - so I know the relay is ok.

Saturday - new ICU (ignition module) arrived from BW. The connector fits properly and (hurrah!) the motor runs.
Unfortunately, it does not start every time . When I hear the pump run at switch on, it starts. If the pump doesn't run, it doesn't start (obviously).
So, I have an intermiittent fault This is not good. Other things to do at the w/e so left it.

Monday - starts first time. Re-starts consistently. Tried the original ICU - starts fine.

I am tending to the conclusion that it was a dodgy earth. See sticky at top of this forum! I had briefly checked the earths at the start of my investigation.
Anyway, I have now thoroughly cleaned the multiple earths on the left hand cylinder head and the earths on the body near the coil. Also checked the electrical connections at the fuel pump - both perfectly clean.

Tomorrow I'll do the gearbox earth mod recommended by Aidan.

Still not happy.

jp

[jpennington]

Just to finalise this post.

I decided not to do the gearbox earth mod - couldn't find a good earth point on the chassis near the starter motor.
Also, it is clear from the wiring diagram that all the earths for the ignition and fuel injection go to the left cylinder head.
So, having cleaned them up, I've now coated them with Vaseline.
All seems good for now - fingers crossed.

Finally, re the ignition unit from JK - I returned it and they gave me a full refund. Their parts quality maybe doubtful, but their service is excellent.

jp