Fuel Pump wont prime ???

[flywheel1935]

Went to prime my ARQ Ruby engine and f/pump felt like it was sucking air ?  (Having just taken out a second mortgage to buy a gallon of fuel I knew the tank was part filled)
Seemed to make a " schlerping" sound while priming, pulled it apart and no obvious issue, such as hole in diaphragm, checked and cleaned 'flap valves', reassembled and it drew fuel.
stopped for tea, about 1 1/2 hours, went to start and no fuel being drawn either from tank, or from alternate gallon can I re routed the IN pipe too, any thoughts.

[AustinWood]

Is the cam in the position where the pump lever is fully depressed? That prevents the pump doing anything. Try turning the engine one revolution.

[flywheel1935]

AW I,m using the primer lever under the pump, as I always pre-prime the carb, before 6 turns of the starting handle/ with full choke/ and it will start first swing.
It's not a cam & lever issue.

[Ian Williams]

I have know pump bodies to go porous between chambers and then stop working as you describe. This is usually a result of corrosion, some pumps that have sat for long periods are in a dreadful state internally.

[flywheel1935]

Ian, think you may well have answered my question. Car has sat for a period, and I can see no evidence of external air leaks. I've a spare body in the shed and will be at Beaulieu, so will look for a spare or two.

[Ian Williams]

Try stripping it down and examine the chambers to see if they are corroded, you may find another reason for it's failure such as crud stuck in one of the valves. I know you have just cleaned it out but you may have missed something less than obvious.

[Hedd_Jones]

it it a T type or a U type?

Sounds to me that you have a leak in one of the non return valves alowing fuel to drop back to the tank and then not sucking it up again. 

Ive found the U type non returns to be intolerant of dirty fuel and pretty unreliable. The t type are much better in this respect. 

The standard test is to suck and blow in the relevant connections. you should be able to suck via the connection to the carb, but not blow. You should be able to blow into the connection for the tank feed, but not suck. 

In a U type the valves are pretty much tamper proof and need to be replaced. On a t type they are just mica disks on a brass seat with a spring. Some mild abrasive usually restores them to working order.

[flywheel1935]

Hedd, how do I tell the difference ? The valve discs are made from 'tufnol' type material, there seems to be 'blow' on the outlet, but 'no suck' from the inlet ?

[Hedd_Jones]

So its a t type. 

I guessed there would be no suck from the inlet, thats why its not pumping!. Amd why tje fuel in the pump backflowed into the tank.

Blow through that inlet. You should be able to blow, but not suck. If you can, the non return (the fibre disk on the brass seat) isnt sealing. Basically the pump cant make a vacum.

Rub the disk in a circular motiom on the brass seat with some mild abrasive. The 'Pink' kitchen cleaner is my current favourite.

I had an issue where the disk seemed to have distorted and wasnt flat, I swapped it for another from spares. There was a link posted at the time where to buy new ones.

Also Asembling them can be tricky, and sometimes the disk doesnt sit down in the proper spot and doesnt seal

[flywheel1935]

Just had a look at the pump chamber and its very corroded ( & probably porous ? ) it could ??? be possible that the crud and varnish I cleaned out may well have been blocking the porous metal, hence its failure to suck ? Just a thought.