Sudden complete loss of fuel delivery

[Vonkie]

Well. The following interesting picture presented itself on clearing out the fuel tank.

The stuff looks like mud. Apparently it is not magnetic (but surely rust can lose its magneticism?) I have not seen it myself. This picture was taken 2 days ago, and in the meantime the stuff has dried and I am told looks like sand. My guy is stumped, as he says the fuel tank was flushed out in November when the silicone was found in the banjo bolt to the fuel pump.

He says the glass bowl filter is clean (i.e. the fuel line filter where I found the little bits of what looked like silicone), fuel system has been flushed, and the car runs well on testing. Tiny hesitations still felt, but theory is electrical rather than fuel starvation. New champion plugs fitted too.

Anyway. I would love some clever theories on what this gunk is. And how it could have got there. I was thinking the new epoxy paint that I was told was applied to coat the tank on the last clean-up could have become this gunk. Ideas on next steps here would also be welcome. I have been swallowed by urgent work crises and unable to attend to my car, but am fetching her tomorrow.

[Geoff Green]

Fuel sitting for a long time will turn into a carbon like substance.

[mgcjag]

Hi Frank....the tank may have been flushed out but a thourough clean out and inspection should be made...if the inside has rusted it will continue to flake of......either sealing the tank inside or a new tank should be thought about....Steve

[Vonkie]

Thanks Steve

That seem like rust to you? Helluva lot, whatever it is!

[jagwit]

to attend to my car, but am fetching her tomorrow.

Myself and two other E-types are having breakfast at Vovo Telo this morning at 9:30 am....

[Vonkie]

Will have to give it a skip - only going to pick her up now and must fetch kids later.

[Vonkie]

The dried up gunk is so fine (not flakes at all), and completely unmagnetic. It certainly does not look like rust. I now have it in my custody, and want to get it analysed.

If it is sand/dirt, then there is a (small and weird) possibility that it got dumped there by a fuelstation which had sand in its underground tank, but this is very unlikely.

Do people agree that the dried stuff in these photos does not look like rust, or paint, but like sand?? And how on earth could that get into the tank? The total quantity is about 3 tablespoons.

[Geoff Green]

Frank,

It will be interesting to find out what this is. I have cut a couple of fuel tanks in half to be able to recycle the steel. Non explosive when in two pieces they say.

One had been sitting for 15 years at least with some fuel (tank still in the car) and when cut in half I found the same stuff you did. I am guessing the fuel returned to it's base form carbon.

Simon might explain how.

Geoff

[Vonkie]

The "sand" came back again and the fuel delivery problems persisted.

The fuel tank was then drained, acid bathed and epoxy lined.

Yesterday I did 60 miles. Today I did 173 miles. She drives beautifully and there is no trace of hesitation in delivery, whether accelerating or coasting. A large part of the drive today was between 85 and 90 mph. Short bursts between 90 and 100 mph. I probably won't attest to that if formally interrogated.

Seems the stuff was rust. Not been analysed yet (yes, a tad frustrating), but the fact that it came back meant it was indeed internal to the tank. Let's hope the lining lasts well.

The Lucas starter is holding up well. Hot starts and cold starts. Maybe I can start looking at those long trips for overnight stays now. I am planning a little adventure one holiday soonish - My house North of Johannesburg to Cape Point (1500km shortest route; realistic route just over 1000 miles). Probably a two stop race. Flatbed on standby.

Meanwhile, I am just loving her. Frustrations and foibles and all - the graph tends towards gradual elimination of issues with much usage. Over 3500 miles since October. At times, a bit of a timeshare exercise with my chappie. But we have a decent thing going. His shop is 20 miles away, so at least fetching her always entails a proper test run! So far, been lucky - no dings, no blow-outs, no idiots smashing into her, no hijacking, no theft. Of course, some days hanging around highways in the middle of nowhere or waving traffic past and feeling a bit spare, on days when I don't really have the time. Getting drunk execs outside a spiffy club to push start her on condition they "can put in an offer". And such stuff. Tiny little nicks from lots of long drives, but nothing more than what is to be expected. Long may that continue.

[Vonkie]

Well, after the fuel tank flush and lining, all went very, very well for a few months with not a sign of any starvation.

Today, she suddenly experienced severe fuel starvation in 4th gear uphill, and then intermittently in other gears on acceleration. So I drove her home. The filter bowl had some grit in it, but it was quite minor, and the residue wiped on the paper towel is shown in the picture. Is this bad enough to suggest there's a fuel system grit problem (again)? After I checked out the filter, she drove perfectly all about town for about 8 miles, including a long uphill in 3rd and 4th. Want to do a trip tomorrow but a tad reluctant to spend the day next to the side of the road somewhere.

[jagwit]

There has been a bit of focus on the choke mechanism on the V12 in a few S3 threads. I noticed that many of these choke mechanisms show severe signs of scoring where two flat plates slide over each other and I wondered WHY that would be, given that the fuel reaching the carbs OUGHT to be rather free of particles.

I now believe that the fuel departing the fuel filter (which is near the fuel tank in the rear on the S3) is clean but the metal line that it runs along rusts on the inside and flakes off to find its way into the carbs (and choke mechanism) where it causes all kinds of problems.

The question must also be asked what affect such rust in the fuel would have on a fuel pump.

With the S3's fuel pump in the rear and metal lines from the tank to the pump and from pump to the engine via a fuel filter, I now hold the view that a modern inline fuel filter should be mounted just before the fuel pump (to protect the pump) and, if the fuel then has to run along a metal line, another filter just before the carburetors OR the metal fuel line should be replaced with a copper line.

[jagwit]

Here is a picture of the scoring I referred to (from the jag-lovers site):

tn_Choke scoring.jpeg (89.33 KiB) Viewed 9213 times

Particles that can cause this kind of scoring can easily jam a fuel feed valve needle wide open or perhaps jam a fuel pump or block a fuel orifice?

[Vonkie]

I have an extra filter at the back close to the pump, in the spare wheel well.

Not sure if I am to infer from your post that you believe the grit bits in the filter bowl are worrying, or normal residue.

I drove her 9 more miles yesterday and 38 miles today with no hint of even a tiny hesitation, despite long uphills in 3rd and 4th.

But I'll have the fuel system checked and flushed again.

O well.

[jagwit]

Frank

We HAVE to assume there is rust inside ALL metal fuel pipes.

On that basis I suggest as follows:
1) Fit an inline fuel filter between the tank and fuel pump (NOT AFTER the fuel pump) - this is to secure fuel pump operation; and

IF there is a metal pipe transporting fuel from the glass fuel filter to the carbs,

2) fit an additional inline filter as close as possible to the carbs between the metal pipe and the carb - this is to ensure no rust from the metal pipe fouls the carbs.

The OEM filter is therefore no longer the primary fuel filter and thus the element from that can be removed for all intents and purposes. Perhaps even a good idea given that you will then have two filters in line between tank and carbs.

[Series1 Stu]

Hi Philip

For the sake of clarity can I point out that when you mention metal pipes you actually mean to say steel pipes. Obviously, rust won't be a problem with copper or cunifer pipes.

Regards

[jagwit]

when you mention metal pipes you actually mean to say steel pipes

Quite correct. Those fuel lines ARE mild steel pipes mostly aren't they? With some kind of anodizing on the outside - on my restored car anyway. I doubt the same treatment was applied originally on the inside correct? Thus exposure to oxygen = rust, correct?

[Series1 Stu]

Well yes. I'm just trying to ensure that people don't feel they need to unnecessarily replace perfectly serviceable non-ferrous pipes.

After all, there's a strong chance that the pipes have been swapped out over the years.

Regards

[paydase]

Seems to me that the original fuel pipes on the S1 are in nylon.
The only steel elements are down the filter bowl after the last nylon pipe that connects to the steel piping dividing along three pipes individually feeding each of the SU carbs.

Very interesting thread btw, I encounter similar issues on my S1 and I think that time has come to thoroughly inspect the tank, the pump, the filters and the lines...

[Series1 Stu]

Don't forget about the fuel pipe from rear bulkhead to the front bulkhead. It definitely is not nylon as standard.

Regards

[paydase]

My mistake.
I didn't kow (nor checked). But looks sound...