The mechanical fuel pump has now been removed and the blanking plate installed.
I found a convenient hole in the inner wing to mount a bolt to (looks like it was originally intended as a wiring pass through - guessing for the marker light which would have been on the wing on US spec cars) which has basically decided where the new fuel pump will be living as it saves me having to drill any new holes.
When I've got more time I may revisit this, either shuffling it over to towards the side a little more and re-drilling things so I can use both mounting lugs, though as it is it's absolutely not going anywhere.
The hoses obviously need to be rerouted, particularly the discharge side line to the carbs as it's now too short. That one is an old line that came with the car anyway so would be getting replaced as a matter of course - I just don't currently have any the right size in stock.
Testing the new pump next to the Hardi one showed that it shifts nearly double the amount of fuel, so probably is better suited to an engine which I'm sure can be "a little thirsty" when being driven in a spirited manner.
I had noticed even when running the previous electric pump (I've not wired this one up yet) that when the car had been idling for any period of time that I was still getting quite severe fuel vapourisation issues. I think I've finally tracked down probably the main reason for that - and that's that the fuel return line is plugged completely solid. That's one of the main ways that this issue is handled on this car, by simply keeping enough fuel flowing through the lines in the engine bay that it doesn't (in theory) have time to boil off. Obviously with that line out of the picture the flow rate is far, far lower (especially at idle), which is why the fuel winds up starting to boil off before it even gets to the pump.
The fuel supply changeover valve is only a couple of inches away from the offside exhaust manifold, and the feed from that then runs right over the top of the bell housing and along the nearside of the engine block - so there's plenty of opportunity for things to get hotter than ideal. I've definitely not discounted the idea of altering that routing somewhere down the line as it really just seems to be asking for trouble with modern fuels.
The immediate problem though is a clogged tank return line - and short of replacing the whole thing (which is most likely what will eventually be necessary) I'm not sure what to do about that. As with everything else aside from the bit between the fuel pump and carbs, this is all made in nylon and metal lines. I have tried the obvious thing, blowing back through it with the air line, and 115psi air didn't even touch it, so it's a pretty solid blockage. I've also tried rodding it out at the engine bay end (as the line does make a near 180 degree bend immediately so I was hoping that might be where the issue was), and it's definitely clear for a couple of metres (the longest bit of stiff enough wire that I had to hand). The lines are easy enough to access under the car as everything is in one bundle that runs along the offside chassis rail until they vanish upwards somewhere in the vicinity of the rear axle.
I pulled a couple of the trim panels inside the boot off to see if I could clearly see where the lines went - the answer being no. However I did discover more work I'll need to do. I'd commented on a couple of occasions that for a 70s British car that I had found the wiring in this thing to contain a surprisingly small number of bodges. Apparently I need to revise that to clarify that the *front* of the car is surprisingly free of bodges. The rear, not so much.
Given the telltale holes in the parcel shelf, we know that there's been an aftermarket audio setup in here at some point - Which almost invariably seems to come with dodgy wiring.
I'm hoping that between that and the tow bar most of this hackery is accounted for and as such will be pretty easy to tidy up/re-run as necessary.
That green wire that's been cut and is just flapping around in the breeze between the fuel tank and trim panel is green with a brown trace - which I believe marks it as the feed for the reversing lights. Which would definitely explain why they don't currently work. I remember it being mentioned that there had been issues with the tail lights on this car in the past so finding this lot wasn't entirely surprising really. However it's a job for another day as had neither the time nor energy to go chasing that any further today. Sure with a bit of time, a wiring diagram and a multimeter we can make sense of it. I'm equally sure once I've deleted obsolete speaker feeds and the dodgy looking tow bar wiring it will make far more sense.
Unfortunately you can't (as far as I can see) get to the feed/return lines on the fuel tank from in the boot. You can see a couple of at least the vent lines, but they just vanish behind the tank somewhere. Guessing that's an under-the-car job then...Yay, that will almost definitely ensure that I get a face full of unleaded while investigating things.
Happily I more or less shrugged the worst of it off after two days but it's left me sounding like Dot Cotton after smoking 200,000 fags!
Seems there's lots of it about...
