Fuel starvation

[Dave Mann]

After 100,000 miles of reliable motoring one of our RNs has developed an an interesting problem, it just stops. I shut the petrol tap and remove the 22FZB float chamber top top to see the float chamber is almost empty, I open the petrol tap and the float chamber starts to fill I refit the float chamber top and off we go. This will repeat after a few miles. I disconnected the feed to the carburetor and found that there is a good flow there, the filter in the bottom of the carburetor was spotless. The needle valve and it's operating gear is intact. Any ideas?    

[David.H]

Is the petrol cap suddenly sealing the tank so it won't allow the fuel to flow? Scuttle tank, so no possibility of a "pinched " flexy.
I had a similar problem with my RK ... 18 stops over a 50mile journey... it was dirty fuel blocking the jet despite the filters...my main problem then was overflowing petrol and getting the level right. Your filter position looks fine. ..I had problems with a modern in line filter which was critical in whether it was vertical or horizontal!

[Parazine]

I had a similar problem with my RM saloon, years ago. Intermittently, the petrol supply "dried up". Eventually, it became more and more of a problem, so I removed the petrol tap and found it was blocked with the legs of a beetle! The rest of the decomposed body was floating around in the bottom of the tank, intermittently blocking things up. A thorough tank clean and clean of the taps and fuel lines followed, which fixed the problem.

[Mike Costigan]

My thought, too, is an intermittent blockage inside the tank.

[Steve Jones]

Have had exactly this earlier this year. As above, turned out to be a blockage in the tap. Pulling the tap to Reserve solved it in the interim as the blockage was in the 'main' stand pipe. Problem was worse when 'pressing on' as car was using more fuel than could get through the pipe. Once taken apart, found a short length of very thin red stuff that I failed to identify.

Steve

[Hugh Barnes]

I also note that the orientation of your fuel pipe may lead to a trapped air bubble preventing flow. However, my Chummy recently had a similar problem overcome by drilling an air bleed hole in the fuel cap. Is it possible that (if you have one) yours has become blocked?

[AustinWood]

We have a similar problem from time to time with the fabric saloon. I'm sure it's caused by foreign bodies in the tank covering the outlet. On the RK there is no filter to catch things.
It got particularly bad at one time and tended to happen after turning right at the roundabout where the Melrose bypass meets the A68. I have a length of flexible piping with union to fit the tap which I attach and blow down. It happened again 2 days ago and all that was needed was to rock the car.
I think we need to get our spare tank reconditioned.

[bob46320]

Blocked air hole in the lid of the float chamber ?? One of the little "levers" in the top of the lid binding on its pin ??

[Dave Mann]

First thing I checked was the fuel tank cap vent. I'll go with Steve and Austin's advice and check the fuel tap assembly for blockages, having had one of the levers dismantle itself on a friends 22FZB i was testing i checked for that.

[David.H]

I also had debris in the fuel tank that moved about!The reserve pipe was missing, so the feed blocked quite easily