Gridgway

Effectively it's not taken from the top off the tank. The feed pipe goes to the bottom of the tank. So in fact there is a very small net column of fuel to provide pressure in the feed pipe.

I think we're all violently agreeing here!

No it's not a gravity feed pump as such. The facet can and does "suck". If you look at the pump spec it says how much. Something like 12" iirc.

Thanks for the explanation. You are thinking of the feed hose from the tank to the pump? Makes sense. I thought your comment was referring to the pressure side.

I don't really understand this comment. What is gravity pressure please?

It doesn't help at all in the core problem. We don't know of any rubber hose spec that will last R6, R9 or R14. It strikes me that the whole industry is in denial of the problem!

second dibs please if it doesn't sell to Nick

I think I'll start a spreadsheet to record what I find. I expect it's mainly all the ancillary bits that are metric. Bolts to hold the coil on, the rev limiter box,, the facet pump, the (bolted) p-clips etc. They are all too long as well!! Should I replace all of those with imperial or leave be I wonder?

As is mine

Brilliant, thanks. I will look and digest.

For my 85 home built bitsa BDR it's a huge mix of imperial and metric nuts and bolts. Are there any resources about the major components and what should be used? And then similar with the ancillary fittings. I know on the ancillaries bolted through things you can use what you like. The builder and subsequent modifiers have used a lot of metric bolts. As a side and probably very dull story, I was confused by a bizaare happening. I wanted new k-nuts for my inlet manifold for the carb fitting (the PO used a weight saving device of only 5 nuts for the 8 stud). I thought for some reason that they were M8 rather than 5/16th unf. I ordered them. Then a mate said, no way they'll be 5/16th. So I got to work with my metric thread gauge and easily found the studs were indeed imperial (imperial gauge on order). Then I checked the nuts and they fitted a 5/16th unf test bolt and not an M8. So the metric k-nuts I bought are imperial. Thanks

Scary! But if it were me drilling, I'd put a layer or two of masking tape down, mark the hole to be drilled with a pencil, then very carefully centre punch it. Enough to make a centring dent, but not enough to put a bigger dent in the panel. Then I'd very very carefully drill with a small sharp drill before drilling out to pop rivet size! Obviosuly you need ti know where to drill! Are you using the one way poppers to keep the half doors on? ETA, do half doors work ok with a full screen?

That's why I think the best thing would be to get them professionally refurbed. I don't have the time to do it myself. I don't have the knowledge either, but it's all learnable (once I have progressed past a PhD)

So just thinking it through, would you expect to see any fuel just opening the throttle with no airflow going in? Should you get a squirt of fuel from the accelerator pump?

They have got the awkward throttle mechanism on top which is a bit of a pain, so I only checked one, but yes it has fuel in the float chamber. I have no idea of the internal plumbing yet - ie how the fuel gets out of the float chamber, but that could be blocked.

I had to finish up so didn't investigate further. I will have to find the float chambers to see. It does seem to be a starting point if the needle valves are jammed. Some research to do!

To conclude (famous last words) I tested the setup on the bench with an LED instead of a coil, see here for vid. Today I put the ignition system back together in the car and tested that there were sparks which there were. All very good indeed - happy ending.

Quick update from me. With a refreshed fuel system (new tank, facet pump fixed, malpassi regulator refurbed, a pressure gauge added and new hose all through) I powered it up and although it took the pump a little while I got nice pressure - too high initially, but regulated down to 3.5psi. No leaks, all good. I expected that the plumbing would be ok, but expected that the Dellortos might leak. But they didn't. In fact no sign of fuel at all from them. I pumped the throttle a few times, but no squirts and no smell of fuel at all. I'll do a bit more diagnostic work, to find out why, but I suspect the best thing to do is to get them professionally refurbed. I used Paul at Weber Carb Reconditioning Services for my Webers a couple of years back and he did a very good job.

Well yes I am blaming the fuel hose manufacturers. R6 is perfectly good for fuel and E10, why doesn't it last?

It's a very strange world of R standards as that hose in its own words far exceeds R14 in almost all regards. I assume one of those is the working pressure. What is it about it that gives confidence that it won't crack like all the others I wonder? And why do they degrade so badly when they are sold as fuel hose suitable for fuel (with ethanol)? The only valuable thing from the totally dire video above was the idea that hoses don't degrade because of ethanol but because they are basically crap!! The hoses on my BDR had completely disintegrated. Annoyingly it was last used in 2008, so I can't definitively tell whether it had ethanol or not as 2008 was when e5 started to be introduced. What do modern cars use and is that what we should be using, not this useless rubber stuff?

Just looked up R14, seems to have a 50psi max. Not suitable for fuel injection

Are you sure? Almost all the descriptions I've seen of R6 hose is that it is Ethanol compatible.

There's quite a lot of different info on R6, R9 etc. So for R6 this one has a working pressure of 20 bar and a burst pressure of 60 bar https://www.autosiliconehoses.com/rubber-hose-fuel-oil-nbr-pipe-automotive-hoses-black.html What I think I know is that R6 is also ok for ethanol (possibly up to E85). There is then R9 which is much more expensive (so must be better) which principally has a (much) lower permeation of fuel. I think that R6 is ok, but I have read that higher permeation makes the cracks appear faster, so it's just a matter of time (as it will be for R9 as well). I'm not a definitive source on this, so if anyone is, then please chime in.

Esso super isn't bio free any more

Thanks Oily, what ECU would you choose for a BDR on throttle bodies to give flexibility to get the best road response (if that makes sense)?