I bought the '34 Tourer in October because I wanted a car I could drive whilst I fixed it, as opposed to two piles of rusty components going nowhere.

I have tried to go to our local town at least once a week, and then fix what needed doing, as it ocurred.

Almost every time, on the return trip, I had a misfire, which would slow me down coming up the hill to home.

I drained the fuel, which was rust coloured. I removed a quarter of an inch of rusty sludge from the carb bowl, and from the chambers of the fuel pump.

I cleared the fine stuff out of the filter in the pump.

I changed the plugs, put a condenser in parallel with the existing one, I changed the leads and the dizzy cap.

I changed the top hose and the manifold, because the water from the leaks was blowing back over the plugs and leaving grubby deposits.

I found a core plug with a pinhole was directing a fine spray over a plug when I was stopped.

I swapped the coil. I swapped the carb bowl. I checked compressions cold, I checked them hot, in case valves were sticking or tappets not right.

I wondered briefly about siezing when hot, but this is an Austin Seven, not anything with tolerances.

All this done over the last dozen or so trips......still the same mis-fire, so I am not going to go too far from home.

On the way home I came to a halt by the roadside. After some investigation, I found that there was no output from the fuel pump, although all was present and correct there, the arm on the cam, etc., etc.

Call for assistance, return with the makings of a temporary scuttle tank to get me home.

In the process of setting this up, fuel was being sprayed out of the fuel pump outlet when I was cranking the engine over on the starter.

So I re-connected the pump, and drove home, almost.. Stopped again half a mile from home. Went for lunch, came back and drove home.

Conclusion: the fuel pump diaphragm de-laminates when hot, fuel starvation caused the misfire.

I have made a temporary diaphragm, so maybe tomorrow I will find out if I am right.

I think this is the first time in 43 years I have failed to make it home!


Simon

Location: On a hill in Wiltshire

I have had some (but not all!) of your symptoms.

The old black diaphragms go squidgy over time with modern fuel. Replacement red ones seem to do the trick.

1) remove tank
2) fill tank with chain or nuts/bolts/washers.
3) shake tank.
4) remove chain or nuts/bolts/washers and rust.
5) blow out fuel pipe with an air line.
6) refit tank.

Will do, if the red dust keeps coming. But I am hoping that as long as I am driving, the tank will clean itself.

Simon

Location: On a hill in Wiltshire

Hi S-A Simon,

In the nineties we had a similar set of symptoms with a Nippy; it ran fine for 60 - 70 miles in a morning but after Lunch went into missfire mode. We thought about skipping lunch but refuelling the driver is important. The penny finally dropped when I rigged up the fuel pump on flexibles to be operated by hand by the passenger - a bit messy but we're broad minded. It ran perfectly and the symptoms could be replicated by stopping pumping. Our solution was to blank the crankcase pump hole and fit an electric pump hidden next to the tank with a filter; it's worked fine ever since. I agree that anything in contact with modern fuel has to be compatable to be reliable and safe - you may not get a second chance with a leaking flexible. Some seem to have no problems with the AC pump but others .............

Inline plastic fuel filters cost something like £1.60....and at a glance you can see what is happening.

Location: Fife

The diaphragm can certainly fail and a new one seems like a good place to start. Also, make sure the lever arm on the pump is actually meant for a Seven. I suffered all sorts of similar problems back in the early 1990's with a pump that would let me down randomly. It took some months for me to realise that the pump was, originally, from a car with a larger diameter camshaft and therefore when fitted to a Seven, it wasn't producing a full stroke. The correct lever solved the problem permanently.

Steve

Location: North Yorkshire

I had the exact same problem with my 1933 Austin 10, it would drive for a while then cough splutter and stop, a few cranks on the starter and it was off again only to cut out a hundred yards or so further on, I ended up using the screen wash bottle as a make do fuel tank with a pipe though the open windscreen and under the bonnet.

Location: Pembrokeshire.

Location: Oxfordshire