Leak down test

Thanks for those replies. The issue with no flow is on the supply line with no mesh only a smaller diameter tube inserted. Blow back up the line from carby side through the tap n hear bubbles then fuel flows like a hose with no restriction. 
That smaller tube is longer and sticks up inside the tank get pick up fuel above the tank bottom. 

20 odd years ago a farmer in drought invented a clam shell to go onto the end of a pump suction so he could suck every last drop could sucked out of the dam before the pump sucked mud

It was on the new inventor type of show back in the day

Something a little like this

 

Not trying to run this thread into the sidecut or anything 

But the secret to getting a reliable flow or maybe it's the velocity with a dirty supply is to reduce the flow 

Just some useless thoughts 

Paul

Cobba, from experience I would say that there is something in your pipe acting like a one way valve such as a torn section of rubber pipe inner acting like a flap or a blob of silicone. High pressure air from both directions will either sort it or point to the trouble.

Thanks,
I think you hit the nail on the head. There use to be an inline fuel filter b ut I removed it b ecause the blockages were inside the tank n virtually nothing getting to the filter. I will check the short filter hoses out and get back.

Replaced the 2 short sections of rubber flex even though they looked new inside. I put more fuel in the tank late yesterday n today there was only hood flow of fuel. So fuelled the rear tank after fitting the copper line n it flowed as well. I shut the tap off n went to do another job on the other side but smelt fuel. Bloody tap leaking past that handle. So drained both ranks n will make a new cork gasket to fit behind the 2 way tap. Don't know if it was the cork dried up or not after a couple of weeks being dry, doesn't matter a new one will go in. 

Did you run something through the fuel lines before connecting them up, I’ve pushed a piece of 0.6 mm mig wire though with a small strip of firm rag on it to clean out the softened "varnish like" deposits from unleaded fuel. Soften the muck with Carby cleaner first
Gumpy

Further to that, an old piece of braided cable in a drill is good, if the bends are not too tight. (guitar string, bonnet cable, speedo cable)

Jarrod.

Yes the copper lines are free of crap, thanks.

So while waiting I decided to paint the steering wheel. It was painted years back when I sprayed the tractor n used Rustolem gloss black on it. I've come to hate this paint over time. It fades so quickly n the tractor is kept under cover n is out in the sun may 2 to 3 weeks in a year. 
So while doing up some of the Mowers I started using Dulux Epoxy gloss paints n so far I'm impressed. Here is the first coat on the wheel.

Made a new fuel tap gasket as the old one started to leak. When I looked closely it had a crack in it. Then after 2 weeks the large sheet of cork gasket arrived so I've made it as well. I found that glass paper used on timber smoothes any rough edges on cork. When making the tap gasket I stuffed up by cutting the outside 1st then when punching the holes it broke through. 2nd attempt I made the holes 1st then cut to size leaving the tabs in place that stop the gasket moving when you turn the handle.
 

Today I checked the tappet clearances n all were perfect. Next I sat the rocker cover on the bench n used a straight edge to check it was flat. Checked out perfect. But then I sat it on the head with no gasket n it rocked. Front left corner had a 1/8" gap. So off to the big vice n starting locking it in the Jaws n bending the metal edge across the front n along the front section of the manifold side. Got it sitting firm on the head do in theory when the gasket is fitted no oil leaks like it always has. So I wiped the area where the gasket sits with thinners to remove any oil n then applied contact cement to the head n gasket. Dropped it in place then sat the cover on n lightly ran both nuts down to apply very light pressure.