Digifant GTI conversion (contains big pictures..)

[Junior Jackson]

Hi Chris – by manifold, I meant the fuel manifold, or rail if you prefer. Both I and the VAG techs (who were a lot younger than me..) were happy about that. They did state, however that there wasn’t a constant return flow so it looks like they were talking out of their arses on that one. I wrongly presumed the return line was just to vent excess pressure and they (also wrongly) confirmed my view…
My presumption is based on the fact that when you turn the ignition on the pumps prime the fuel lines for a second or so. They then stop until the engine runs. This I interpreted as the pumps running until the fuel rail is at the correct pressure and then stopping – i.e. if there was a constant return flow I would expect the pumps to run continuously – obviously this happens when the engine is running.

Fair comment about changing the line, I am happy with the pressure capabilities of the 5mm line as it is constructed with the same wall thickness and from the same material as the GTI 7mm return line, the only thing that concerns me is the restricted flow capabilities (I am an Instrument Engineer and know a bit about pressure and flow etc). I know that to be exactly safe I need to 1) never speak to a VAG technician again and 2) change the line for the GTI one. Really I should change it for a new one as Chris’ traumatic pressure split concerns are of more concern when you factor in that the pipe hasn’t moved for 18 years and I’m going to bend it around pulling it out of clips etc but I’m on a budget and will inspect the pipe as well as possible before refitting.
Whilst it’s kinda in bits etc…

[Chris S]

I also have no qualms over the pressure capabilities of the pipe material, only that the restricted return flow will increase the back pressure in the system causing problems with pump life (it has to work harder to mantain flow) and the risk of petrol leaks & fires etc

btw, if you look at your pressure regulator valve at the return end of the fuel rail you will see it is vacuum controlled to function when the engine is running.

[Junior Jackson]

Got loads done over the last week or so – haven’t had much time for updates but will put some picures up tuesday.

Got both front ends dismantled for decent access to engines. GTI engine just needs exhaust and driveshafts disconnecting and engine mounts unbolting and it’s out.

My original plan was to remove the engine loom from the GTI, labelling it up as I go, transplant that to the Syncro and then swap the lump but on inspection, it’s actually easier to keep the entire loom on the engine and just disconnect the external bits (ECU etc) and the fuse box end and swap it all as one.

I’m leaving the lighting loom in the syncro, just swapping the engine loom. The two looms go through the bulkhead to the fuse box seperately.

The rallye lift pump and sender are in place and the inline pump got bolted up today. I have swapped the larger GTI fuel return hose – easy once it’s through the chassis leg…
To finish the back end, just have to fit the 4 pole connector to the cable for the lift pump / sender and hoses need fitting to sender unit – I used the GTI hoses from the inline pump to the tank and just extended the flexi hose at the end (as the syncro tank top is further away then the GTi one).

Jim and I swapped the full dash loom last weekend so the MFA stalks and clocks are in place. The biggest arse with this was getting the cable for the heated washer jets out of the GTI – it actually runs through the bulkhead behind the (impossible to remove) glovebox and along the metal crossmember at the back of the dash, under the glued down sound deadening…[!] It must be the first thing they put in the car! Had to rip the entire dash out to get at it and it isn’t going in the syncro the same way – it can run through the engine bay and back to the fuse box with the rest of the cabling… Vacuum line is in place for the MFA on the clocks.

Another couple of hours should see the fuel lines and wiring all connected at the back, then it’s on to disconnecting exhausts and driveshafts. I’ve managed to get one of the spring clips that connect the syncro exhaust to the manifold off – the other is proving a little bit of an arse. Also one of the nuts that hoold the exhaust heat shield on is u/s so I can’t get it off easily which appears to be preventing me removing the manifolds from the head which is also a bit of an arse – will have a better look at this later in the week. Hopefully this weekend I’ll hire a crane and get the lumps out and maybe even the boxes swapped over and the GTI lump and 020 box back in.

Haven’t spent any more money so cost is still at £145.94 which is nice..

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