2.1 waterbox DJ (auto) won't idle

[Brockybwoy]

2.1 waterbox DJ (Auto ) won't idle

I've done a top end rebuild of engine after water gaskets blown
1st time it happened everything went fine .. wondering what I have done wrong this time

I have replaced starter, dizzy cap , rotor arm ,fuel and air filters
There's strong spark on all plugs and The fuel injection system appears to be ok
I have tightened throttle cable so there is no freeplay . I have loosened throttle adjustment rod adjuster so idle circuit clicks in with foot off pedal.

I've double and triple checked to make sure all electrical connections are where they should be and I've static timed at 5 degrees BTC to get it running .
Idle controll valve is humming and I've bypassed ICU unit by joining the plugs together

I have been fiddling with the idle speed screw and found a sweet spot where engine starts 1st time, but it only runs for a few seconds then stops, . Turning the screw either way for a full turn and it won't start without throttle, tighten or loosen it further and it won't start at all .

Any suggestions It's driving me nuts ... TIA

[maxstu]

Vacuum pipes check? They must have a nice tight fit.
Weak fuel pump. Delivery volume correct?

[Brockybwoy]

Thanks Maxstu .

I replaced all vacuum pipes as precaution but a weak fuel pump something I hadn't thought of . I'll check it tomorrow and update accordingly .

[maxstu]

Good luck. I share your grief
Six months' of unreliability driving me totally mad. Took it to a VW trained specialist nearby.
He ripped out the ICU. I MEAN LITERALLY right in front of me. Two plugs together. Reset gap on spark plugs, then timing to run on normal unleaded, and its been dandy ever since.
I have a used spare fuel pump if you need it to test.

[maxstu]

Ps.
Whereabouts are you?

[maxstu]

Ive just recalled another thing.
Relay for injectors or fuel pump issue. Someone in here recently had a dodgy relay causing similar symptoms

[Brockybwoy]

Hi Maxtu ,

1st apologies for not replying sooner, since partial lockdown easing (less here in N Wales )I have been trying to numb the Van pain by going fishing . However my Mrs is starting to nag me again in the hope we can take off later in the summer .. bypassing ICU unit was 1st thing I tried ( one of the very few useful tips in Haynes manual ) .
I will need help from her to do fuel pump test . but will static time clean and check plug gaps 1st . They were all pretty sooty after the few times it started needing lots of throttle.

[HarryMann]

Once started using throttle, will it idle thereafter and drive OK? You maybe need to get a few miles on it too... then worry about a throttle free startup