mk2 gti 8 valve 1990 wont start

August 30, 2022, 10:16:15 PM

Hi,

my 1990 gti CE2 wired car 1.8 8 valve does not start, I had to join AA and towed home.

So far I have looked over the relays as one was chattering, never found which one as never happened again. Bench tested (80 - fuel pump relay slot 12) and (32 - ECU Digifant slot 3) both held on when powered on bench and provide closed switch contact on pins as expected. Whilst in the fusebox, I touched the relays and seem to operate from feeling and sound, plus they power up fuel pump (hear it priming) and the buzz from within engine bay. The other relay I checked out was the x-over relay which clicks off powering down heater fan etc.

Checked all fuses, all good.

I thought I may have a faulty ignition switch, but the relays seem to do what they are supposed to do.
EDIT: reason I thought this was when I had all keys on bunch, and I used to bump them with hand car would judder. I removed non essential keys.

There are splices from immobiliser, stereo and alarm. I had removed these months ago and car has been OK since. The wierd remaining splice was black wire (switched ignition live) to thick red black (starter cranking power), really don't understand why they joined that half way down harness.

The fusebox is dry and no corrosion.

In the engine bay the rotar arm contactor plate was twisted and I flattened it, filed down the four contact pins to each cylinder - no change. Bought new rotar arm and cap. No change. When you hold a spark plug to engine wall and turn on ignition you occasionally get a small spark prior to cranking over engine (probably due to rotar arm in right place). Once got a spark from main cable from coil to dizzy cap by holding it close to engine block. Any sparking stops after initial spark even prior to cranking. Cranking gives no spark on any plug.
EDIT: fearing its the hall sensor on dizzy. Going to check for fuel pump running when cranking (only know its runs during priming - need to confirm during cranking)

Spark plugs not soaken from petrol, slight smell of petrol from combustion chamber.

Engine block and gearbox is earthed. Rest of car electrics seem to work so I don't suspect it is earth faults somewhere.

Spent two days grabbing bits of info from this forum which has given me the info to start my basic troubleshooting, but I feel I have have missed something.

Any advice appreciated.

Regards,
Garry.

Re: mk2 gti 8 valve 1990 wont start

Reply #1 – August 31, 2022, 10:34:07 AM

Hi Garry,

From the sounds of it, you've got a spark issue, all four leads should spark per revolution, if you test it off the kind lead from the coil, it should spark a fair bit.
It does appear to be a hall sender, had that exact fault, had a spark on ignition on, then nothing while cranking.
Swapped out for another dizzy and it fired up.