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Dave Jenner

Rolls Royce B80/81 Engine

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On an Alvis Salamander that has had the fuel tank out to resolve brake issue; now having difficulty with getting fuel back up to the carb after removal of the fuel tank. It's a B81 with Solex Carb and manual fuel pump which is located below the carb low down on the front of the engine. It has a lever for manual operation on the fuel pump despite operating this it stubbornly refuses to draw any fuel through! Anyone experienced similar on this engine type or is there a knack or something I'm missing? Dave

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The mechanical fuel pump needs to be in A1 condition in order to prime itself from 'dry'.

I get a similar problem with Fox fuel supply (although it has an electric pump). The slightest leakage past the pump valves, the fuel tap seal or a pinhole leakage in the suction lines gives the symptoms you describe.

 

My solution is to use a manual priming bulb (like those used for outboard motor remote fuel tanks) in series with the fuel pump. This will fill the system with fuel and can be later removed. They usually work ok after this...if not its a fuel pump rebuild i'm afraid...and a thourough checking and re-sealing the fuel suction lines.

 

Jon

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I've had similar problems, I disconnected the fuel feed to the carb and made a seperate gravity feed to the carb, started the engine and ran it fairly fast for 30 seconds or so and that seemed to get the fuel moving through the pump into a can.

Good luck

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I did get it running with a gravity feed and ran it for about 30 seconds. The temporary fuel tank is right under the driving position under the seat but it did not pull any fuel through. Machine Mart do one of those fuel bulb transfer tools that Jon mentioned for a tenner so I think I might give that a go!

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Also be aware that to use the manual lever efficiently the fuel pump needs to be "off cam" so you are getting maximum travel of the diaphram. If it is "on cam" you will only get a tiny movement when you operate the lever, try cranking the engine slightly so the camshaft rotates the lobe away from the pump piston.

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Hey, thats not fair, you've got "SPACE" arround your engine.........

 

I solved all my fule pump problems on Ferret, Saracen and the Saladin by going electric.

 

Andy

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Hi Dave,

The way we used to get the petrol to the pump on these engines, after they had been standing without fuel, was to get someone to slacken off the fuel pipe at the carb, then get and air line and put some pressure in to the fuel tank either via the breather pipe through the filler with suitable material to block the air in (;)). This will soon push the petrol through the system. Might be worth checking for any pipe joints that have been disturbed first, in case you are drawing air, otherwise you will soon find the leak! You will be surprised how little air is needed to do this.

 

How are the brakes now?

 

regards Richard

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I did this with a ferret , and it works well but you only need a very low air pressure so that you don't do any damage.

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I did this with a ferret , and it works well but you only need a very low air pressure so that you don't do any damage.

 

As you say, not a lot of pressure is needed and putting the air gun nozzle in the filler with a wad of rag it cannot build up much, but it is enough to push the fuel up the pipe.

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An in-line bulb hand pump at the fuel tank end did the job quite easy in the end. I had a temporary fuel tank which held a gallon...it lasted all of ten minutes and about 500 yards! Thanks for all the tips, Dave

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