Have had some problems with my mk1 not starting in the past, mostly it was caused by the fuel pump fuse blowing, upon investigation the fusebox had been getting hot as some of the black plastic showed signs of heat damage around the fuse for the fuel pump. I carried out a oil and filter change recently and afterwards it just would not start, engine turns over so carried out some fault diagnosis. Fusebox was heavily corroded so have replaced it with a new one. 83 Gti so fusebox available at Heritage. Still not starting, the fuel pump is not priming, I have bridged the relay and still not starting. There is not 12v at the fuel pump. Have put a supply voltage across the terminals of the pump and it does work. I believe there is a signal from the coil which goes into the fusebox and primes the pump, unable to find any diagrams which point me in the right direction. I have been over the engine bay looking for any loose wires etc, still need to check the earth. To note the whole car went through an extensive rebuild 3 or 4 years ago so it is clean and tidy in the bay. Metering head has been refurbished by KMI last year. Anymore tips would be appreciated, not quit at the end of my tether but any advice will be appreciated.
Did you look at the fusebox Diagrams RubJonny has as stickies in the electrical section here on forum? CE1 electrics. Worth having a good look at your earthing points, and the fuel pump relay.
Yes, RubJonny's guide is excellent and thorough. I could test the relay but bridging the fusebox bypasses it as I understand it and it still will not with the pump when I do this.
I'm no expert but if bridging the relay has not got it going it would suggest there is no power getting to the pumps, i.e. a wire break between fusebox pin E/14 and the pumps. Have you unplugged the fuel pump plugs/terminals and checked for 12ish volts on the loom plug pins when your turn the key two clicks? Does both the lift pump and the main pump underneath the car fail to run or just one? I would also be checking ground at the plugs for good continuity
swap the 17/18 relay into the fuel relay socket, this will then go live with ignition which is helpfull for troubleshooting. If you've already looped a wire across the 2 large terminals though this should give you permanent live to the pump, but the relay will make life easier as you dont have to keep fitting and removing your loop wire. with the relay fitted if you dont have 12v to the fuel pump next check is at the fusebox pin E/14, if you have live here then as MK2daz said you have a break in the wire between e/14 and the pump. if not, then there is a problem with the relay socket, fusebox wiring, fuel pump fuse or socket. Check to see if you have 12v at the large spade N, this is wired between the relay and fuse. if the relay isnt clicking with ignition on, check you have a good earth to the fusebox. its the thick brown hanging out the back of the fusebox white D plug, this should go to the 4 way white spade block on the headlight loom chunky brown wire.
