Evening all, Recently my 1996 8v GTI (AGG) has been throwing a wobbly. Upon turn of the key, all the usual startup lights on the dash appear, but there is no whirring of the fuel pump priming. The car has done this temperamentally before, then after countless attempts it started. However now it's back into an extended sulk and isn't playing ball. From my understanding, the faults could be ... ignition switch, immo ring or fuel pump. Are there any more sensors/items that operate on the fuel/starter circuit? Wiring inside the car is fine, i fixed a shoddy solder tonight. Fuse is fine (20A) and relay is fine (167), both have been changed already. I'm at a bit of a loss now, so any ideas are much appreciated. I'll source a spare fuel pump and new ignition switch next week to try out too. Tom
I've got a small update on this - i plugged in a friend's code reader (cheap one) to see if any codes could be found, and the code reader operated all circuits to find faults as usual, and the fuel pump buzzed into life. So i'm ruling out a broken fuel pump. The wiring on that circuit and all others i can see is fine too, so i've ordered up a new ignition switch and will replace that. Mine's 22 years old so hopefully age has just killed it. I'm hoping to borrow a proper vagcom laptop from another friend soon and plug the car in to check immobiliser and ignition switch faults. It bloody better work as i've just booked a trackday in late August haha lol
since the dash lights up this suggests the switch is ok, a quick test is swap the 18 relay into slot 12 and see if the car fires up ok like that. if not ecu isnt powering up properly, check the ecu relay #30 these are cheap enough to buy from VW
Ok thanks Jonny, I've tried a couple of known working #167 fuel pump relays which did nothing so i'll try #18 too just in case. If the dash lights coming on shows the ignition switch may be in working order that's good news, as they look like a right oik to change with that pressed collar on the steering column. One point that may be of interest too is that normally, my throttle body makes a chirp on ignition ON and the stepper motor thrashes around a bit (VR6 throttle on an 8v so probably reason for silly noises) BUT since having this no fuel prime issue, the throttle body hasn't been heard. ECU relay sounds like a good shout, i'll order one from the dealership on the way home. I can hear the parts guys gleefully running for the card machine already ...
Ah sounds more like ecu power issue rather than fuel relay or control circuit if the throttle isnt doing anything either. The 18 relay will bring the fuel pump on with ignition regardless of what the ecu is doing so is handy if you're testing out parts of the fuel system, but as I say probably wont do anything for you. fuse 15 also supplies the ecu with a 2nd ignition live, I think the ecu will still power up without but its worth a check anyway.
Ah that's interesting, so irrespective of a faulty #30 ecu relay the fuel pump should prime with the ignition? As in mine i'm not getting any throttle body chirps (suggestive of ecu issues as you said) but then also i'm not getting the fuel pump priming. A multimeter shows between 0 and 0.4V power to the fuel pump when ignition is switched on and when the engine is cranked too. So not the 11.9V that i was getting previously. I checked relay #30 last night and will order a new one today, and also fuse #15 which is fine. I will beat this gremlin eventually, even if it takes a 16v G60 swap lol
I'm not 100% on the later 8v, but I think a faulty ecu relay will stop the pump priming & throttle buzzy, but a blown fuse 15 or damaged ignition live to ecu will not. regardless, if you make yourself a little jumper wire and loop it like so, this will bypass a faulty ecu relay for testing:
Perfect, thanks Jonny! I'll rustle one of them up later and give it a go. Thanks for your help and time
Closing out this thread - plugged the car into vagcom laptop today and an immobiliser fault code is the culprit for the car not starting - faulty immob wiring. I've just posted in another thread dug up from 2009 regarding this exact code and will trace through my immob wiring to neaten up the remains of when a Sigma alarm was removed many moons ago. Fuel pump and relay are both operational, ignition switch is fine, ecu relay is fine, all fuses fine, immobiliser wiring is the issue. I'll add photos of my findings and fixes to the other thread and hopefully permanently eradicate the problem. Thanks to Rubjonny for your continued help and all others that offered advice! I'm now on the right track.
Hi. Did you have any joy with this? I know it's an old post but I have the same issue and have also removed a sigma alarm system so it would be great if you have any pointers
