Mk3 gti 8v HELP PLEASE wont start something weird is going on

[Kmad]

Hi Guys ! First off all name is Chris. All though i wanted to join this forum in happy mode and circumstances such as moding etc story is different  and i have a huge problem 

2 weeks ago i bought a lovely clean black ,box standard '96 gti 8v with 100k on the clock..all was good first week although sometimes car would start and cut off but always start second time and i was suspecting some flat spots around 4000rpm but that could just be me and it wasn't a big deal!   

One day coming from the pub car refused to start altogether and red oil light flashes....

I have replaced fuel pump relays and resoldered those suspicious ecu relay no30 joints,  checked every fuse ,disconnected ecu end checked conectors,swapped fuel pumps,checked for sparks all good  still nothing

Weird thing is that when i disconnect the fuel pump and connect it to a direct 12v supply it works ,primes and supplies fuel to engine.Engine then starts no prob runs for minute and then cuts off when it uses all the fuel from the line...
When i check voltages coming into the plug that connects to the pump it shows 12v when ignition is on then it drops to 4V and again goes up to 12v when i crank it!!! But when i connect that same plug into the pump nothing happens pump is dead engine wont start ......what the &€@-,!!?. is going on??? Someone PLEASE HELP?  Am I going mad!!!???.

[Kmad]

Anyone ?  I have been reading all the posts and cant find anything similar, help guys before i burn it 

[Abf83]

Im not sure on the fuel pump but the oil light flashing is probably the oil pressure switch or could be the wiring to it. Check for any damage on the wire if not change the switch. Just check oil lvl also. Have you checked your fuses? Maybe it could be that.

[Kmad]

Thanks for the reply man, yeah oil is topped up and all fuses are ok, wiring to the sensor also ok... Would a faulty oil press sensor prevent from starting???

[boneybradley]

don't worry about the oil switch at the mo, it wont pressure up without the engine running correctly.

To me it does sound like a fuel pump relay issue. Can you test another relay? (never buy used)

The only other things I can suggest you check is the fuel filter for a blockage, check the ignition switch and also look at the immobiliser

[Kmad]

I have put in another fuel pump relay from a car i know is working 100%, havent checked the fuel filter though...imo ilizer i rhink would cut out ignition but i have spark or maybe i am wrong... Again i am confused that the car starts when i conect the pump to direct 12v supply!!?? Can it be the crank sensor would it cut off fuel id it was faulty??? Thing is when i crank it rev counter goes up ?

[dixie180]

If it cuts out and oil light flashes,i would say Crank Sensor is gone(same happened to me).Like boneybradley said,use brand new fuel pump relay.

[boneybradley]

you could also try and can on vag-com and see if any errors come up.

it may not show your fault but worth a try (I could scan if your close by and others users may offer a free scan if you don't have a reader)

[itavaltalainen]

check hall sender with a LED test lamp, should nicely flash on centre pin when you crank, if not replace complete distributor where it lives....

quite a common 1.8/2.0 8v issue.

[Kmad]

Bench tested fuel relay and tested it in in my 1.4 golf which i have for spares all is good... Will test the hall sensor... But still what confuses me is the fact that car starts and works fine when i connect  the pump to a direct 12v source plus all the voltage readings at the plug are correct... Tomorrow i will take to a garage and have it connected to diagnostics...