>Hello. I have a few questions about my '75 MGB.
>
>1. I have discovered that the PO had removed the standard SU Fuel Pump and
added a small electric pump under the hood after the fuel filter and before
the CD175 carb. I think the original pump (located on the boot kick board
on the right side ?) had some kind of pressure shut off. This
non-standard pump seems to run constantly from the time the key is in ACC to
the time you switch off.
Yeah, I saw those "aftermarket" fuel pumps once or twice. A little
thing that could fit in the palm of your hand. If nothing else, the
constant clicking is a distraction. They look like something that
would go in a Hundai or a Ford Escort (very el-cheapo looking).
>Q: My carb is running rich, and I am rebuilding both the carb and pulling
the engine for a rebuild this weekend. Should I look at replacing this
pump with an original? If I use my handy Zenith-Stromburg tool can I keep
the carb from flooding the engine? How about float adjustment?
Any fuel pump should create a "constant" pressure at the fuel input
of the carb. If your fuel pressure is too high, pick up one of those
$10 "Fuel Pressure Regulators" between the pump and the carb.
The constant clicking would not be a refusal of the pump to stop
pumping, but instead, must be a designed-in feature. All fuel
pumps MUST attempt to create a constant pressure, or they are
not fuel pumps at all.
If ya wanna get very fancy, fuel pressure gauges are available, and
can be used to find the actual fuel pressure at any point you wish
to measure.
Most fuel pumps "expect" to be installed near the tank, and "expect"
to be pushing fuel through a goodly amount of fuel line, the fuel
filter, and so on. Therefore, your problems in the area of high
fuel pressure may be valid concerns, but you should be able to
adjust the carb and/or install a pressure regulator.
>I notice that MOSS sells a replacement fuel pump that they say is more
reliable than the SU. I can't tell if it runs on or is pressure sensitive.
Dunno - ask them. They have a technical support line. If SU pumps
are so lousy, why does Volvo use them? Methinks that Moss is selling
"fear" on this issue.
>My bogus pump is new - Should I drop another $90 US and get the SU or can I
fix my fuel problem with carb ajustments?
Well, I have the dual-ended SUs (the crowd gasps in awe and envy),
and the only problems I have ever seen can be traced to 2 sources:
1) The pump wears out, and needs to be "rebuilt" with one
of the rebuild kits. This is a rather simple task, if
one uses the exploded diagrams in a good shop manual,
and lays out the parts EXACTLY was they are found during
surgery in an orderly manner. The first thing to fail is
usualy the little "one-way" valves that are about the size
of a US dime. They just plain "break", which is no big
surprise, given that the membrane looks rather like
some sort of wax paper.
2) The wiring to the fuel pump comes loose, the pump itself looses
ground, or whatever. MG Midgets in particular are a pain, since
they have wiring harness bullet connectors UNDER the car that
can come undone.
I think that SUs are "better fuel pumps", since they provide a
fail-safe warning that you are just about to run out of fuel.
If an SU pump starts to "thump" without stopping, you are very
very very low on fuel, and you have about 3 mins find petrol!!
This advantange alone as saved my posterior several times, since
Midgets seem to run off the fumes of nearby 55-foot tractor
trailers, and I sometimes forget the minimum required monthly
fill-up.
>ALSO:
>Q: What is a good way to de-carbonize plugs ? (I can sand or scrape them,
>but is there a cool solvent or something that removes carbon?)
How to decarb your plugs:
1) Remove the plugs from the block.
2) Dispose of them in a safe manner.
3) Install new plugs.
4) Natural processes will return the carbon on the plugs
to the earth, thus making oil, coal, or even a small
diamond for future generations. Now don't you feel
better?
Don't waste your time, when even the fanciest plug you can buy
(the "Splitfire" is only $5 or so)
As an aside, has anyone tried the "Splitfire" Plugs?
Has anyone tried the "Splitfire" Plugs in a Spitfire?
The 2nd Law of Thermodynamics says "Natural processes increase entropy".
Translation - "You think you're in trouble now? Just you wait..."
james fischer jfischer@supercollider.com
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