Anti Siphon

[RichardS]

I 'm aware that the thread is not recent, but it might be of interest: I took my new and 'perfect copy' (all metal and with a mounting strap) Racor FG 500 apart yesterday before starting to install it. There was quite a bit of resistance in the inlet pipe, and applying pressure with a bulb produduced a 'popping' sound. There was no ball inside, but at the bottom of the vertical pipe is a simple rubber non-return valve with a spring. I can very well imagine this flow restriction offering resistance to greater demand from the engine.

For installations where the level of fuel in the tank is above the level of the filter, the NRV is a waste of time anyway and could be removed as the fuel cannot drain back to the tank anyway.

In fact, even where the level of the fuel is lower, I'm not sure that draining back in that likely unless the end of the fuel return from the injectors is above the fuel level in the tank, and I've a feeling that, to prevent undue aeration of the fuel, that might not always be the case.

Richard

 

[david_bagshaw]

In my set up the racor NRV, stops the pipe from the tank to the filter emptying when changing the racor filter. filter is well above the top of the tank.

As to the original posters problem, I had a similar problem caused by a dead mouse being wrapped around the uptake pipe. this was some 10 years after build!