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Re: [T3] Fuel in oil

> > The spring is responsible for drawing fuel into the
> > pump, not providing the pressure out to the carbs.

The operating rod is rigid and driven by the camshaft- if you follow through
with this idea, the pump would have to provide a constant flow of fuel that
would have to be constantly fed to the engine- in a linear manner depending
on engine speed- we would not need needle valves! or carbs at all for that
matter. This is not the case and if the pump worked this way the carbs would
flood the engine, or something would explode under the hydraulic pressure
developed ;-(

> That's beginning to make sense - the Beetle and Bus tanks are potentially
> up, so the pump wouldn't have to 'suck' as hard.  The Type 3 tank is lower
> standard Beetles anyway) and about a foot further away.  On a downslope
> would be greater suction needed for the Type 3.
> Certainly 1600 Type 2 buses, with their greater fuel demand than Type 3s,
> the Type 1 pump.
> That could explain a difference between the spring arrangement - now why
> different pressures?

I'm wondering if the need for a higher pressure pump than T1s and buses is
to do with the fact that we (except the FIs and single carbs) have twin
carbs, and therefore 2 float chambers to fill when the needle valves open-
the effective pressure can be halved as its shared between 2 valves. To keep
the level in the carbs correct, in the right period of time, it would
therefore need to shift twice as much fuel when the valves opened and would
need more pressure.

I've been listening in on this one because I had the exact same problem at
the same time as Daniel- my oil level had risen noticeably soon after an oil
change. At the time of the oil change I had enriched the mixture on my carbs
by 1/2 turn. The engine was really running smooth with that change, but on
inspecting the plugs they were pretty sooty. They weren't that bad though.
After the tips Daniel recieved, I decided to look at the pump. I had a
Brazilian Brocar T1 pump on there that required using a shorter (99.5mm)
drive rod. On removal there was no evidence of petrol leaking from it- the
grease was all there. I replaced it with an NOS white nylon cover pump I
bought last summer at a swap-meet - I had been meaning to do the change for
a while for other reasons. After it not working because I got the pipes the
wrong way round (doh) the engine now has quite a different character. It
seems to run a little more "constantly" and feels more solid and "German"!

I still have no idea why my engine should want to run so much smoother on
too rich a diet, but i've now got a hunch that we really do need the higher
pressure pump for optimum performance. They wouldn't have made it different
for nothing would they!?
I'm also none the wiser as to the cause of my petrol diluted oil. Surely if
the carbs were that much too rich, the engine would have trouble running at
all? I know I have a problem with the choke on my L carb- it opens a lot
slower than the R. I'm about to fix that. I also do a lot of short journeys
so the choke has a high average influence on the fuel consumption. In my
wildest dreams I'm hoping that if I fix the choke, and with the new pump,
everything will be hunky dorey again. Fingers crossed...

Mark Seaton
'73 1600TA London

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