New WEBER Fuel Lines, Inline Fuel Filter Position

[oldchieft]

No, you have not quite got it straight.

The SU is a pump, you feed it with fuel and electricity and you will get pressure at the carburettors.

When you switch on you should get a rapid clicking from the pump, this should slow down.

When the carbs are filled and the float is closed the clicking will slow to a few clicks every few seconds.(if the valves in the pump are good the clicks will be fewer)

The starting being good or bad is nothing to do with the fuel feed if the pump is working as described.

A a facet posi-flow / regulator setup won't change anything with regard to starting it will just change one pump for another.

I would take the pump off and get a can of petrol and pump from the can and back to it with a 12v supply.

If you have a gauge Teed into the return line you can pinch the return hose and the pressure will rise when it is pinched off completely you will know the full out put pressure of the pump.

If it works OK then you have saved the price if a new pump. If you are a bit shy of using petrol round a 12v spark from a battery then test it with a can of white spirit.

Jon the Chief

[rcourtney]

Great advise - many thanks!

[rgh0]

Hi Ralph
I think you are misunderstanding what is going on here

The SU pump will run rapidly until it fills the carb bowls and the float valves shut off after that the clicking will slow down or stop until fuel is being used.

You need to pump the accelerator a couple of time to get a rich enough mixture by pumping fuel from the accelerator jets into the engine intakes this has nothing to do with the fuel pump. If you don't pump Webers when cold with 2 or 3 strokes of the accelerator pedal they will not start.

I doubt the "inline device" as you call it is a pump or anything to do with priming. It has a small arrow and appears to have a single wire going to it but it also is not earthed from what I can see. It is most likely a flow cut off valve intended to shut off fuel flow when the power is cut. It appears to be wired in parallel with the fuel pump so it gets power and opens when the pump operates. However if it is not earthed then it is probably not working and may be restricting flow ( the suction of the fuel pump may be all thats partially opening it and this may be why your having problems).

If the wire that appears to go to the inline device does not actually go their then it is probably just a fuel filter and it may be blocked

cheers
Rohan

[rcourtney]

Think I'm getting there

Really appreciate everyone's responses .. This is the first time I've ever really 'tinkered' with anything. It's been a steep yet reward journey so far. Apologies for my novice assumptions.

Rohan,

I think you are absolutely correct with regard to the in line device. It appears to to a cut off and most certainly not any sort of additional / bypass pump as I had initially concluded. It's wired to earth.

In summary,

I have an inline fuel cut off (wired to Earth) that leads to a modified 'AXZ series' SU pump* (it's half a pump - the AXZ should be made up of two independent pumps that can take supplies from two sources such as a reserve tank).

* thanks to Jon the chief for identification

See better pic of what's going on below -

Ralph

[Plus 2]

Wow Ralph you really have some good advice here but let me just clear a few points.

I have been rebuilding SU's (Skinners Union) carbs and pumps for many many years and when Austin Rover were selling out as progression to fuel injection came along I was in negotiation with my late Father in Law who was an executive at the AR/BL group to actually purchase the company.

It is now named Burlen.Co. Ltd and all spares are readily available http://sucarb.co.uk/?SID=45s4lamk9p4lqb ... __store=su

Indeed there were low pressure and high pressure pumps made, originally 1.5 psi (LP) and 2.7 psi (HP). Incredible to think 2.7psi today could be thought of as a HP pump but indeed it is still used to describe the SU pump.

Later HP pumps were increased to 3.8 psi....................for sure any LP SU pump is too low for Webers at 1.5 psi and the 2.7 psi even border line as Webers from my best recollection work best at around 3-4psi.

Looking at your installation my first observation is the pump is not orientated correctly. The pumps can be fitted vertically (electrics/points uppermost) but if fitted horizontally then the smoother chamber (top hat looking part) should be mounted at the top and the fuel lines exit entry from the side.

There should be NOTHING between the tank and the inlet side of an SU pump not even a filter. The pumps are quite capable of passing small debris and indeed as stated the webers have a small adequate filter in each carb, but more important any restriction on the inlet side of an SU pump can cause a stall condition which can burn out the coil. These SU's were standards fit on RR, Aston's, Jaguar's, Triumphs and MGB's and one excellent site is http://homepages.donobi.net/sufuelpumps/ who has recorded just about anything you need to know about SU's.

Now what further concerns me is the 'shut off valve' you have in line.......indeed I may be wrong but it looks more like a cruise control air dump valve..........perhaps not even suitable for fuel and indeed if any rubber internals not suitable for modern E fuels. Furthermore though if I am wrong in that from my experience in line fuel valves are usually fitted on the output side of a fuel pump in the line pressure side where the pressure assists shut off and the pressure assists complete opening. Albeit I am sure there are many different types.

I cannot quite tell with the picture which pipe is which in the connection but if on the tank side then it certainly should be removed. Ideally with an SU inertia cut off valves in the electrical circuit is what should be fitted and I see absolutely NO value in this installation that the solenoid could provide anyway as the SU pump will not flow until energised.

So in summary yes the pump is a modified twin from a Jaguar, Aston Martin or Rolls Royce type.......depending on the exact model could be a 2.7 psi so a little low for Webers. I never actually converted a twin to a single so not sure what has been done with the internal valves on the blanked side or how it would/could affect output.

Now for the bit of bad news. One of my roles in past years was involvement as a technical 'observer' to insurance, fire, police type forensic teardowns where in some cases establishing causes of vehicle fires was paramount, mainly trying to establish the genuine from the DIY or where fatal injuries had occured and product knowledge was required for stripdowns.

Many engine fires where fuel related can be complicated but then many could be atributed to incorrect aftermarket fuel pumps turning out up to 10 psi and un regulated. Whilst technically your set up may be low it does not need regulating as max would only be 3.8 psi. However being in the UK it is very important that you advise the insurance company of this type of modification. I appreciate many people may not realise such modifications may have been done, but in the event of a claim if say the vehicle went on fire and it was determined the source was from the set up you could find yourself possibly compromised on any settlement.

It appears this is not so much an issue across the pond but you will find with ALL UK insurances it will be asked fairly early on in the questions and always best to disclose what you know. I even disclose my tyre ratings, wheels and any upgrades or where an original equipment part cannot be sourced. At no time have I been penalised or added cost to the quote.

With respect to the engine cranking too much before firing I always advise to check out the vacuum pipes to servo and chassis chamber and make sure there are no air leaks. One simple test on a non failsafe is pop the lights up cut the ignition and see how long they stay up for. If quick to drop down then suspect a bit of leakage which does not help with starting at all. Bad enough it has to create a vacuum in the chassis reservoir to begin with and certainly if mechanical fuel pump and left for a while does not help either. Failsafe assume the reverse Here was one happy forum member lotus-talk-f50/starting-from-cold-with-dellortos-t32293-15.html#p216906 and a point to note 9 times out of 10 the issue is not the carbs despite the first thing most start to adjust

Regards

Steve

Pics of some recent resto's

[oldchieft]

And here is the one I restored.


Jon the Chief

[Plus 2]

And here is the one I restored.


Jon the Chief

Not bad Jon for an oldchief .

To be correct though the tape should go over the rubber but I do agree for future strip down and access it is annoying to have to destroy the logo tape everytime as SU will not sell it albeit it is available on eBay.

Originally there was no rubber or tape many many years ago. The rubber was added due to atmospheric damp/water moisture ingress and a vent hole included in the end cap to prevent spark fume film over the points.

The rubber often rotted and perished due to exterior locations (I use old scooter motorbike innertubes BTW) so the tape then was wrapped around the rubber band that sealed over the cap to solenoid body joint to keep the rubber in tact.

Modern purchases from Burlen I dont think have the rubber now and are just taped over the joint with SU logo and then a piece of red ot black tape to denote if polarity sensitive.

I still have around 200 NOS various models from when the AR sites were cleared as the pumps were often built at the factory car manufacturing plants.

Regards

Steve

[oldchieft]

Yes they don't give any rubber band tape or the Logo tape.

I use self amalgamating tape to seal the gap.

When I placed the order I asked for the Logo tape with the overhaul kit and the person who took the order said it was included.

When it came without the Logo tape I kicked up so they sent me some to shut me up.

But I like the SU pumps, so just to put it to good use I have it in the line between the mechanical pump and the Filter King for priming the Webers, just press a spring loaded toggle switch for a few seconds and then fire up.

Not really necessary but it amuses me.

Jon the Chief