Fc170 10 Posted October 3, 2018 I am having some trouble with my 93 Corrado VR6. The car will start without issue but dies after a few minuets. It will start right back up again but dies again in a few minutes. I have put a fuel pressure gauge on the system and found that the fuel pressure is good at start up but then drops to 0. Putting a meter on the fuel pump leads shows that there is voltage when the key is in the crank position but no voltage in any other position. I have replaced the fuel pump relay. I am wondering if this could this be an ignition switch issue or am I dealing with ECU problems? Thanks for your help Quote Share this post Link to post Share on other sites
seanl82 23 Posted October 4, 2018 Once the key gets to position 1 it should energise the relay, which will hold open the current path to the pump. The fact it's only getting voltage at position 2 (when cranking) suggest a wiring issue rather than the switch. Turn the key with your finger on the relay, you should feel it engage if it's working correctly. If so, your issue lies between relay and pump so you've narrowed it down a little bit Quote Share this post Link to post Share on other sites
fendervg 33 Posted October 4, 2018 Is there an immobiliser circuit fitted across the fuel pump wires that could be kicking in again and cutting it off? The fuel pump is either on or off and runs and maintains a constant pressure of 3.5 bar, the ECU does not control it. Quote Share this post Link to post Share on other sites
Fc170 10 Posted October 4, 2018 Thanks for the replies I checked and the fuel pump relay does click in the #1 position. I don't know if there is an immobilizer in that circuit. Is there a way to bypass or disconnect the immobilizer? Quote Share this post Link to post Share on other sites
fendervg 33 Posted October 5, 2018 Do you have an alarm fob or dongle that you need to start or open the car? You'll need to find the alarm/immobiliser control box, if there is one. It will usually be behind the driver's side dash trim. There are usually a number of pairs of wires coming from it, these will have been connected to each side of the fuel pump and starter circuits for example, so as to insert the immobiliser circuit into the current path. If you can find the joins you can simply reconnect the cut wires to bypass. The only issue is that these wires are usually all the same colour so as to make them more difficult for miscreants to trace. Quote Share this post Link to post Share on other sites
Fc170 10 Posted October 5, 2018 Thanks I'll look and see if I can find a control box. I do not have a fob that goes with the car and to my knowledge it never had one. Quote Share this post Link to post Share on other sites
