Hi all, basically want some info about relay 162. Recently but an early MK2 GTI in bad shape after changing fluids etc i came to start it and it wouldnt. Anyway been doin some investigation today finally now the snow has gone. After looking through the haynes the only drawing i could find with the fuel pump connections on was for the 16v so no real help. I understand that when ignition is switched on it should prime as i used to have a 16v and that did but was 90 spec so no real help, anyway terminals 31 & 15 should go closed circuit on ignition to close terminals 30 & 87 and applying 12v to both pumps. This only happens though when you crank the engine but wont prime the engine before hand. Can anyone tell me what terminal 31A does as im assuming something should happen between 31 & 31A on ignition to complete the circuit between 31 & 15?? I believe it has something to do with the rev limiter on the fuel pump relay so should that be getting a ground from coil?!?! It turns out main fuel pump is duff (tested a spare and works) so that needs swapping but doesnt explain why it wont prime? Any info would be greatfully appreciated.
There are different versions (of Kjet fuel pump relay). Some prime, some don't. 8v generally don't, in my experience. Some need an ignition pulse feed (think it's to 31A) to convince the relay the engine is sparking and run the pump - it's a safety feature.
I had this problem with and 86 k-jet check wiring to coil and check earth to battery this sorted our problem. Just clean them up worth a shot worked for me.
31a is a rev counter signal from the coil, this is what triggers the relay to fire the pump. as above some relays prime and some dont. i have a theory that the actual reason you sometimes get a prime is on some cars when you switch on the ignition you see a single spark, this in turn may trigger the relay and in turn makes the pump 'prime' makes no odds if it primes or not the fuel pressure will be up to spec almost immediately when the pump runs while cranking
