Did I buy a duff fuel pump...?

[bigherb]

I've bought a clone of the Lucas FDB502, which has a short priming function when ignition power is applied to the coil. Having now tested it, the duration of the priming timer is so short (closer to 0.5s than 1s) as to be of limited use I'd have thought, but maybe that's all it takes.

That was the old XR3i relay. It varied from relay to relay but all that is really needed to pressurise a fuel line.

Have you wired it correctly the terminals are not immediately obvious.

Pin 1-3 = 1 or TD Pulsed feed from Coil Terminal 1
Pin 15-11 = 15 Ignition switched feed
Pin 30-28 = 30 Battery voltage
Pin 54-15 = 87b supply to Pump
Pin 31 = Earth

[CJH]

Thanks Bigherb - despite the diagram on their website, the terminals on the relay itself are actually marked as per your earlier diagram (1, 15, 30, 31, 87), so it was straightforward. So far I've only tested continuity across 30 and 87 when applying battery voltage across 15 and 30. I haven't tried the tachometric function yet.

[CJH]

Well, now I've got the relay, and I've got my head round the wiring, I might as well go the whole hog and fit an electric pump. I had been planning to fit a second hand Pierburg mechanical pump to my new engine, but electric seems like a sensible option. I don't want to risk the oil in my new engine ever being diluted with petrol. The downside seems to be that if there's a leak in the pipework I'll get a spray of fuel, whereas with the mechanical pump it would just suck in air. That bit worries me a little.

So I gather the Facet 1.5-4.0 PSI version is the one to go for. There seem to be a lot of 'Facet-style' pumps for half the price of the genuine Facets (e.g. this one, although this model is higher pressure). Are they worth the risk?

Also, is there any advantage in using their 'fuel filter union' over a simple plastic inline filter? I like the plastic ones because you can see whether there's fuel, and whether they need changing.

[bigherb]

So I gather the Facet 1.5-4.0 PSI version is the one to go for. There seem to be a lot of 'Facet-style' pumps for half the price of the genuine Facets (e.g. this one, although this model is higher pressure). Are they worth the risk?

You need the Facet Posi flow pump 1.5-4 psi
http://www.ebay.co.uk/itm/Facet-Posi-Fl ... 540e2e28ae" onclick="window.open(this.href);return false;

Also, is there any advantage in using their 'fuel filter union' over a simple plastic inline filter? I like the plastic ones because you can see whether there's fuel, and whether they need changing.

It is better to use the original plastic filter before the pump you can see if it has dirt in it and is a finer screen than the plastic gauze in the metal filter.
Replace the unions with a 8mm, 1/8" NPT taper thread inlet union and a 6mm outlet union some of the sellers on ebay allow you to specify the union sizes from the standard ones you get with pump.

[CJH]

Thanks Bigherb. My fuel lines are 8mm all the way up to the existing mechanical pump (8mm inlet spigot), then there are 6mm spigots on the pump outlet and the carb inlet. So rather than getting a 6mm outlet on the electric pump I believe I need 8mm on both sides, and then an 8mm to 6mm reducer in the engine bay.

[bigherb]

Yes it just need the fittings for the pipe size, Brickwerks does the original nice 8-6 mm reducing hose if you still have the plastic fuel line.

[CJH]

I'd never noticed that reducing hose - I have a brass reducer in my return line. I have a spare reducer too, so that'll do for the inlet side now. I replaced the plastic fuel lines (which had already been butchered) with 8mm Kunifer a couple of years ago, so the hose connections are all quite short. The only slight concern I have is that the Kunifer isn't flared, so I'm relying on quite a long overlap of hose, and a hose clip. Not an issue with a mechanical pump that sucks, but maybe a slightly greater risk with one that pushes. I don't really think this is a problem, since the tank spigots aren't flared either.

[bigherb]

It doesn't matter if there is not a flare, the original plastic hard line and some of the carburettor unions where straight.
The rubber hose should be slightly smaller diameter than the hard line, hence we use 5.5mm and 7mm hose for 6mm & 8mm hard lines which makes them a tight fit in themselves and combined with the tendency for the rubber to stick makes them quite secure.

[CJH]

Thanks again Bigherb. Yep, those are the hose sizes I've been using. All changed in the last few weeks too, so should be easy to adapt to the electric pump.

[CJH]

I finally got around to fitting my electric pump today. This is the one I bought back in May.



I can't get the unions to seal in the pump though. I can't make my mind up whether they've very slightly tapered fittings or not, but they do seem to get tighter as they're wound in. But no matter how tight I make them (and the instructions say only 10-15 ft lbs), they still dribble fuel - at quite a rate on the outlet side.

So are they supposed to be assembled with some kind of sealant, maybe a threadlock or even some PTFE tape? Are either of those going to resist petrol?

[bigherb]

Yep, PTFE tape.

[CJH]

Thank you - I'll give that a try in the morning.

[CJH]

That's got it - a couple of turns of PTFE tape on the threads of each union and it's all dry now. Thanks again.

[CJH]

The fuel pump seems to work fine - a quick whirr when I turn the ignition on, and then it runs continuously while the engine's running. But boy is it noisy when mounted directly to the chassis. I could even hear it over the road and engine noise from the driver's seat.

So I bought a pair of the mounting bobbins, and now I can't hear it at all, even listening from outside.



I've left the mechanical pump in situ for the time being, with no hoses attached, while I gain some confidence in the electric pump. It can't do any harm can it?

[andyhems]

Hi could someone let me know if this one is the right one for a 2lt petrol CU engine as well (is low flow 1.5-4.0 psi) as it looks like this thread is for the diesel engine? Thanks