Hi folks, Apologies in advance if I've missed this info, but I've searched and haven't found anyone with exactly this issue.. I have a standard PB 8v - CE1. It's been standing for years. After further investigation inside the fuel tank all the lift pump rubbers have turned into a sticky black mess - horrible. I've managed to get hold of a MK3 8v GTi fuel tank and in-tank pump to replace/update it, plus filter for under the car and the fuel lines up to engine bay. (future 20vt engine conversion planned, as MK3 VR6/MK4(?) pump fits inside the MK3 tank). Fuel line connections have been covered, my question is regarding the pump wiring and relay. Before it was parked up, the lift pump used to prime for a couple of seconds on first ignition. What is going to happen now if I just match the sender and in-tank pump wires?? It looks like the old PB 8v main pump under the car was wired in parallel, so the relay primed both pumps? Is it really as simple as matching the wire colours in the boot (I have the MK3 loom plug too), and cutting off the under car main pump? Sorry, quick question - long post! Cheers, Tim.
These should cover it http://www.clubgti.com/showthread.php?271915-wiring-in-a-mk3-fuel-pump http://www.clubgti.com/showthread.php?263928-which-fuel-tank-for-20v-mk2 During fitting you will need to remove the wiring down to the old main pump it's clipped in between the flow and return fuel pipes and looks a bit like a pipe. Cut up the double pole connector it is jointed into in the boot behind the seat. Chew the plastic up first then cut the wires as close as you can to the terminals. The Mk3 pump connector is pinned out in a different order to the lift pump/sender, but uses the same wire colours for power and the sender wires. All that needs to be done is release the Mk2 loom sender wires Purple/Black, Brown/blue one at a time and replace like for like in the Mk3 connector. Then lead the Mk3 brown, Red/Yellow power wires up to the old two pole in place of the Mk2 ones. I have a terminal release tool, but I think there was another topic recently with some info from John about using two pieces of 0.8mm welding wire. Oh and if you have any old fuel left in the tank especially if its unknown age and it isn't going to be fully used up any time soon pump it out and replace with some fresh. That should give you another year or so.
i would use the wires to the old main pump to power the mk4 pump, you'll note they are thicker gauges than the mk2 lifter. but as above its a case of chop the old stuff off and splice to new. only thign with CE1 is you only have 3 wires, mk3 has 4 but its easy just splice the brown and brown/blue to the mk2 brown job jobbed. edit: you might find the old main pump wires are a bit grotty and wont solder well, if so chop back till you find fresh and chop out a longer length of mk3 wire from another donor in scrappy. all petrol mk3s have the same plug so not hard to get one. the main pump loom disconnects at a 2 pin plug near the front of the boot, you'll see what i mean. you could just chop it before the plug and splice there, you have no need for that plug once the main pump is binned
Awesome, cheers! I've come across one of those threads before, will get stuck in soon and see how it goes. Even though I'm CE1, I'm pretty sure it's already 4 wires - car is right on the changeover though at 1989, so that could be the reason. Any worries with the relay back at the fusebox still trying to prime the pump? As the lift pump no longer exists, I guess there's no reason for it to need to move fuel to prime the main pump - theoretically the main in-tank pump is already full of fuel as it's submerged. Yes, had a nightmare trying to get rid of 20+ litres of really stinky old fuel, turns out the lawnmower loves it! Mixed 50/50 I'm slowly getting rid of it all... Tim.
both pumps are on the same power wires, so the relay would be priming them both. mk3 golfs also prime the fuel pump so dont worry
Mine was a four pin as well, personally I don't see the point in using the old main pump power wire with no junior power timer connectors on the end if you have the Mk3 4 pin and enough Mk3 loom to get back to the double pole in the boot. You should finish up with Mk3 plug, Mk3 power wires retained with Mk2 sender terminals and loom supplanting the Mk3 wires. I know my explanations are terrible. If I have time I'll do a mock pictorial guide.
Thanks again everyone, much awesome-ness as usual to clarify the loose ends! I have about a foot and a half of MK3 loom with the plug on the end. Assuming by double pole in the boot you mean the end of the main loom before it branches off to the original fuel pump and lift pump. Keep the MK2 sender wires from this point and connect into the MK3 plug, and connect the new MK3 wires from the plug into the main loom here. Will hopefully be starting this soon, Thanks again, Tim.
This is the double pole molex still with a bit of sticky on the back I remember what I did now you just separate it and release the terminals from the loom end and cut close to the terminals. You can then remove the section leads down to the main pump This is the (late?) 4pin Mk2 lift pump/sender plug Just release the first sender wire and place in the Mk3 plug (not pictured) like for like. The Mk3 plug has the sender wires paired in the middle, power on the outside. Then the next wire. The seals piggybacked on the terminals have quite a grip and even with the proper tool it doesn't feel like it's done the job of releasing them. These are power wires Mk3 pair on the top Mk2 below. A bit deceptive from the outside as the Mk3 is thin wall insulated as well as bigger CSA. If you go for a Mk3 pump it will work with the Mk2/3 gauge. I think you will need a Mk4 gauge to work with the Mk4 sender.
Cheers, it would be nice to put it altogether in one thread. I need a few more pictures and some posts from about 5/6 other threads.
