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6 cyl Bristol cars Type 400 to 406 - restoration, repair, maintenance etc

Fuel pickup and reserve unit

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Old 08-06-23, 10:10 AM
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Default Fuel pickup and reserve unit

The fuel pickup on my 403 seems to be suffering the effects of its advancing years. The upper pipe no longer shuts off and the gauze has disintegrated.

Has anyone managed to repair one of these or found a specialist who can?
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Old 08-06-23, 11:29 AM
CEL CEL is offline
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Default Fuel pickup

I believe SLJ in Warminster can sort it.
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Old 08-06-23, 11:37 AM
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I have discovered that Four Ashes garage can supply a new unit but it's nearly 500. Just checking if there is an affordable alternative before I raid the piggy bank.
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Old 08-06-23, 03:32 PM
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David

The 4 Ashes garage units were alway reco units years ago which for that amount of money was crazy. If they are now new check that the pipes are the correct length as per your original bristol unit. They were also fitted to Rovers ( I think P3 and 4 5 and 6 DB Aston Martins but they are usually no better than Bristol ones. The unit in my 411 worked electronically but the ball valve in the unit leaked. Never could get it going so I have blocked the shorter tube so I am drawing fuel from the longer tube.

Interested to see how you get on. None of my cars have the unit working (403 411 and 412)

Regards Peter Dowdle
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Old 08-06-23, 04:17 PM
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A little more browsing on the 4 Ashes site suggests they can refurbish the units at a cost in the region of 400. This would include a new solenoid and replacement body that will work with E10 - unlike the original.

They advertise a unit specifically for the 403, so I have to hope it will be the correct dimensions.
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Old 08-06-23, 10:59 PM
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David thank you for that I hadn't checked the site for years. I will have to sell one of the back paddocks to buy 3 of them at that price and to put fuel in the 411 and 412. The joys of Bristol motoring !
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Old 18-06-23, 12:09 PM
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I have now stripped and cleaned the reserve unit.

For anyone with the same problem or just curious I submit pictures of the inner workings.

http://www.bristolcars.info/forums/a...1&d=1687089366

The top cover is an interference fit. Remove the clip holding wire to body and prise cap off along with coil. Unscrew inner part of solenoid and be prepared for Mazak sludge or for a copper ball to leap out.
There are two springs inside. One in the body of the unit that pushes on the ball. The other in the travelling part of the solenoid.

It may be possible to unsolder the brass gauze and remove in one piece to clean the pipes but there is a fair chance it will turn to dust in your hands. Replacement brass gauze / fuel pickup sheet available on Ebay if you are handy with a soldering iron for sheet metal.

The shorter tube on mine was completely blocked but cleaned out fairly easily with a welding rod flattened at one end.

So, cleaned up and reassembled. Tested with a battery. Reassuring thud from the solenoid and...

Hopeless. No discernible shut off of upper tube. I'm pretty sure the Mazak has failed between the upper end of the tubes in the casting. Time to get 4 Ashes to rebuild it with a new head.
Attached Images
File Type: jpeg Reserve 1.jpeg (101.8 KB, 33 views)
File Type: jpeg Reserve 2.jpeg (99.2 KB, 23 views)

Last edited by David C; 18-06-23 at 12:16 PM.
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Old 27-05-24, 04:26 PM
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My 411 S5 was suffering from the strange problem that shortly after the fuel gauge showed half tank, the motor stalled. When the reserve switch was on, the motor continued for another 10 km and then ran out of fuel.

I replaced the fuel pump with a stronger unit: no change.

I checked the fuel gauge and sender unit: everything fine here.

Finally it dawned on me that the fuel pick up might be the problem. So today I took the unit out of the tank and a close inspection showed that the brass pick up tubes were full of hairline cracks.

I cleaned the brass tubes and soldered up all the cracks. Normally the brass tubes can be replaced fairly easily as they have 7mm outer diameter, but I was not able to identify the thread on the end of the brass tube that threads into the mazak top.

Question: which thread size was used by Lucas for a 7mm tube ( the thread has 26tpi)?

For reference purposes: The Lucas number for my pick up is 78037B and the Lucas catalog states a length of 9 35/64 for the main tube and 11 51/64 for the reserve tube.
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File Type: jpg IMG_9446.jpg (243.0 KB, 10 views)
File Type: jpg IMG_9442.jpg (409.8 KB, 10 views)
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Old 27-05-24, 07:23 PM
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I don't know for certain but 1/4" BSB is a strong possibility.
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Old 27-05-24, 08:05 PM
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Thought so too, but the brass tube has outside diameter of 7,0mm
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Old 27-05-24, 08:21 PM
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M7 ISO has a pitch of 1mm which would give 25.6 TPI
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Old 27-05-24, 08:30 PM
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Too bad I did not try M7x1 to proof this. Now the unit is installed again and I can not verify this. But did Lucas really used metric threads in the 1960-1970s ?
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Old 27-05-24, 08:33 PM
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I didn't think so either but perhaps they bought in some parts. The Solex on the Bristol have metric threads.
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Old 28-05-24, 05:39 PM
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I talked today to Four Ashes Garage they sell new brass pickup tubes for 25 each. And yes the thread is M7x1! The prize goes to David C for naming the correct thread !🤣
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