Rewinding a fuel reserve solenoid

[David2021]

Can anyone suggest a company that can/will rebuild the solenoid in the Lucas Reserve fuel unit?

[SHyslop]

I've been hoping there would be a reply to this as I too could have done with one being repaired. Having failed to find a repairer, I did find a new old stock P5 unit which uses the same general arrangement but has a bend in the pipes but it should be possible to remodel it into the same configuration as for a P2.

However, what to do with a broken unit? The way I see it is that the operation is purely that of a solenoid which pulls on when the switch is moved to Reserve and springs off to Main. Being 12 volt, a similar idea in size is a point motor for a model railway but these are on/on and can be operated by passing contact switches so that power isn't required once the movement has been made whereas on the electric reserve solenoid, it appears to remain energised until turned back to main . However, I have seen this :

https://www.ebay.co.uk/itm/401403373678

but have not yet had a chance to compare its size to the original. I feel there must be potential to resuscitate these units with some proprietary item suitably modified to replace the solenoid and connect to the valve. It is, after all, a fairly simple electro mechanical unit but of the type which the iphone generation has left behind, hence the difficulty in finding repairers.

[paul williams]

I was able to repair one for a P4 a few years back. The operation is the same. The coil was showing open circuit when tested, I decided to unwrap the coil to see how much wire was used and save it on another bobbin. Luckily I came across the 'break' quite soon, in fact only after a few turns were removed. I think the break was due to some kind of previous impact on the outside of the coil. Rewinding shouldnt be difficult, I have rewound large 12v relays before using a slow drill in a vice. After all there is nothing to lose. A 12v solenoid similar to the one you linked to could be made to work I am sure.

The main problems I have come across are the 'ball' not seating properly or the pick up tube leaking air. Both issues stop it working even if the solenoid is OK.

[David2021]

I have taken the easy way out and taken my dismantled unit to Four Ashes Garage (who are a couple of miles from me). They have remade them for (primarily) DB Aston Martins ( and price the accordingly) They also do them to suit Rover, Bristol, Armstrong etc
I am nervouslwaiting for an estimate....

[David2021]

Well, for a new solenoid, steel parts re-plating, pressure testing for cracks in the tubes, reassembly and test etc about £200!...
A new one is about £500 from them
Maybe a Christmas present to myself! perhaps a glass panel in the boot floor so it can be gazed at in wonder!
Luli said he just "took his to a local workshop who rewound the solenoid!" in Tel Aviv perhaps, but not round here!

[RobHomewood]

I am now confused when you talk about pressure testing tubes whether you are talking about the fuel sender unit with the main/reserve solenoid and dip pipes etc or the fuel level indicator with the moving arm and float. I have sourced both items (Lucas look alikes) for my P2 on the internet without too much trouble apart from some delay waiting for a container load to replenish stocks from USA. (Holden also supply the side mounted version of the fuel level indicator for the sump oil level indicator) The problem I had with the fuel and oil level indicator units was that they seem to develop a leak (petrol) around the arm bushes into the coil area and short out. I still havent worked out why there isnt a big bang but so far so good!
Rob

[RobHomewood]

PS Sorry I think I said Lucas when I should have said Smiths type units
Rob

[astonchap]

I am resurrecting this thread as I have an easy cheap fix for the frequently experienced problem of failing fuel reserve valves. I have an old Aston which uses the same system as Rovers. I bought a job lot of failed P4 valves for experimentation. A short pipe draws fuel normally. When the fuel level falls below the short fuel pipe you ‘run out’ as the pipe is sucking air. You then pull the reserve switch which illuminates the dash warning light and energises a solenoid. This pushes a ball valve against the spring which normally holds the ball off the top end of the short pipe. This forces the ball against the short pipe orifice closing it off and restores suction from the pump. This allows fuel to be drawn through the longer fuel pipe.

All of the valves I bought suffered from the same problem as mine. The wiring to the solenoid – a 12V electromagnet – had perished and disintegrated. They can be fixed with great care and skill but it involves considerable risk as the insulation on these old hand wound coils is poor and the unit operates adjacent to the fuel tank. Even if yours has not yet failed it is likely that the wiring to the coil and the insulation will be very fragile.

I therefore looked for a modern properly sealed and insulated solenoid that was of a similar rating and of a size to fit over the tube containing the actuator. I found this on eBay for under £20 - https://ebay.us/m/FOW2tb . It is rated at 11 Watts and 12VDC, and so operates at just under 1 Amp.
To fit the new solenoid, you unscrew the cable clip and twist off the original dust cover with a vice grip, pulling off the coil with it. Slide the new solenoid over the actuator shaft. Connect the positive and negative wires to the spade terminals which are marked.
Here it is fitted to my unit and working fine.

valve.jpg (40.73 KiB) Viewed 97 times

It should now click with a 12V battery and when you blow down the short fuel pipe you can feel it shut off. You can secure it in place with a large star washer.

If it doesn’t click, unscrew the knurled ring holding the actuator shaft, using a vice grip. Clean it out with carb cleaner and ensure the actuator and ball move freely. Replace the sealing washer with similar and reassemble and test again. Eventually it should work, hopefully. Good Luck.