Carburation

[peterg]

Not sure what you meant by holding the priming lever in position Geoff as the position of the diaphragm in relation to the operating lever is fixed.

Replaced a valve that didn't appear to be working and refitted. The car started in a cloud of smoke and settled down. But after about 5 minutes of driving around, just as I was about to back it into the garage it cut out and once again would only restart if on full choke and primed. Then in runs for about 8 seconds and cuts out.

I am beginning to wonder whether the diaphragm spade is locating securely in the operating arm as the petrol level is only at the level of the gauze filter. Is this a common point of wear in AC pumps?

[peterg]

Latest progress. Checked the pump and the diaphragm spade is still locating securely in the operating arm but after use the petrol level is only half way up the glass bowl.

Will replace the petrol filter and check the flexible line. Not much else I can think of.

[flyinghorse1]

The diaphragm can be attacked by ethanol & perish--is it intact? You would soon know as petrol would enter the oil system & oil pressure would drop.
You can get ethanol proof ones now.

I had problems getting a good idle and I eventually made new gaskets for the stubs that the solexes mount onto the head,using hylomar on all joints and surgically rebuilding my carbs.

I cant fully recall but the float needle valves may be worn /sticky. I got new rebuild kits from gower & lee.

Note the only level setting is by means of varying the packing washers under the Needle Valve and as Geoff says the 16mm is critical.

I also found that a leaking water pump meant erratic firing on front cylinders,and I had 2 duff plugs as well.

[peterg]

No the diaphragms are good.

I did change the fuel filter today as it had some crud in it. No improvement.
Final check. Undid the union, turned the fuel tap on. Nothing. As the fuel gauge reads half full and is probably correct the fuel fuel line is blocked.

Makes sense. But how to clear it? It's a long way from the fuel tank to the isolation tap.

[flyinghorse1]

Peter,
You really have to drop the tank & sort out why crap is getting through.

I have had this as a student in a Hillman hunter and used to carry a foot pump to pump the crap back to the tank from the engine side . However it always returned.

I also have a vintage Swift that did this-and cut out like you said. The motion must be mobilizing fines & clogging the line.

You may get lucky by draining the tank & starting afresh.

Frost do a slosh kit that should fix the issue if you get the tank out--I have used it in my Swift & a friend in an AC Ace and it works.

POR-15 Car Tank Repair Kit | Frost Auto Restoration Techniques

Graham

[Geoff Dowdle]

peterg,
What model Bristol are you working on ????
If it is a 403 (AB2 engine as you advised) the bottom of the tank has probably got a lot of corrosion in it and might need replacing .

The fuel lines often get squashed where they go under the chassis , just forward of the LH rear wheel area . Foreign matter can get blocked in this restriction.

If you want to fix the problem properly I suggest you inspect for leaks , remove the tank , initially clean & inspect it internally , if a alloy 401/3 check for corrosion holes , replace the fuel line & filter (I assume you have a proper disposable filter between pump & carbs).

You should then have a clean fuel system to the carbs which will be a good position to then start a correct tune up.

Geoff

[peterg]

Got to the tank today and there is a layer of sediment at the bottom that wasn't there two years ago and a partial block on the elbow into the tank.

Cleaned the blockage up and the engine is running. So well that it doesn't stop when the ignition is turned off! Another new one on me.

I will need to rig up a fuel filter in the boot as mine is in the engine compartment and there is plenty to clean out.

Can't get the fuel gauge to operate. It either reads as full, empty or just over half full depending upon where it is wired in.