Vaporisation problem and fitting an Electric Fuel pump to your �D�
Series
The Problem.
Since we have
owned �Lady Penelope� our Sheerline, she has suffered with acute fuel
vaporisation which coincided with the temperature gauge reaching about 180
degrees. Her demeanour became very un-lady like. �Elizabeth� our Princess does
not have that problem, the reasons for which are explained below.
I found that the
Sheerline engine compartment can become very hot, mainly due to the radiant
heat coming from the exhaust manifold and engine pipe. The effect of this
radiant heat is that the exhaust manifold side of the engine becomes
intolerably hot causing the mechanical fuel pump and the fuel line to heat up.
Unlike our DM4 Princess (which has the fuel line on the right hand side of the
car, crossing to the left at the front cross member, and has an electric fuel pump
about amidships on the chassis), the Sheerline fuel line runs along the chassis
on the same side as the exhaust pipe and becomes quite hot and results in
pre-heating the fuel. This fuel, in its journey from the fuel tank to the carby, reaches the hot fuel line and very hot fuel pump
which is struggling to pump what has now become vapour. This condition is intensified
in stop start traffic. If you have just stopped the engine and try to restart �
you will find it near impossible to achieve it until things cool down. If you
are driving � the engine will starve for fuel and could backfire and will most
likely result in the engine stopping very soon.
The Solution.
So, what can we
do about this I asked myself? The obvious solution is to reduce the heat at the
fuel pump and fuel line. Relocating the fuel line slightly is also a good idea
and can be done by undoing the locating clamps on the chassis in the engine bay,
moving the fuel line closer to the wheel side of the chassis, turn the clamp
around to face the new fuel line position and tighten. A heat shield between
the exhaust and fuel line in the engine bay would also help. Check the gasket
between fuel pump and engine. It should be a thick gasket providing a degree of
insulation between the engine and the fuel pump. Again, one can fit a heat
shield between the pump and engine pipe. A good mounting position for a shield
would be the top of the engine mount bracket. The carby
also gets uncomfortably hot and can do with a thick insulating gasket between
it and the manifold if it doesn�t have one.
Although I have
suggested the installation of heat shields (made of say 1/8� to 3/16� polished
aluminium sheet) I have not done this myself yet. Instead, I decided the
quickest thing to do without altering the appearance of the engine bay too much
was to fit an electric fuel pump.
There are two
fundamentally different types of electric fuel pump. A
�sucker� and a �pusher�. Because I was fitting the pump at the rear of
the car I naturally used a �pusher�. The local auto electrician sold me a
compact fuel pump unit complete with rubber mounts to insulate from any sound
made by the pump. I purchased about 1.5 metres of fuel hose and some hose
clamps. I already had some automotive wire.
I looked for a
good place to mount the fuel pump and decided the rear of the LH battery box
was as good a place as any. I removed the LH battery (replacing naturally when
the job was finished) then drilled the holes necessary to mount the pump.
Next, I used a mini
pipe cutter, to cut the fuel line� and what a gem it was because it made the
job clean and easy. I would not suggest using a hacksaw because the filings
could enter the fuel line. �I made the cuts
in the pipe, removing about 6� of pipe, just before it enters the cruciform
part of the chassis and again just rear of the battery box where the chassis
begins to flatten out after going over the rear axle,.
I measured, cut with
a sharp knife and fitted the hoses to the fuel line going to the pump, clamping
them using jubilee clamps. Following the instructions provided, I fitted the
hose from fuel tank to the input on the pump and the hose going to the
front of the car to the outlet side of the pump.
The
electrical wiring. I
ran two wires from the pump to the terminal fuse board under the bonnet, in the
box. The power was picked up from the Auxiliary Ignition fuse and the Earth
from terminal "24" on the board. The pump will not operate if the
wires are not connected to the correct terminal nor will it when the ignition
switch is OFF.
The last thing I
did, although a good idea but not essential, was to fit an �off the shelf� fuel
filter. These are cheap as chips and easy to fit. You will be amazed how much
rubbish can be in the fuel. The wires and hoses were also tied back to the
chassis so they looked a bit neater and didn�t dangle under the car.
I ran the car with
the manual pump in-line for about 500 miles and have now bypassed the manual
pump totally. I have had no vaporisation problems since, even when the temp
gauge was at 190 degrees.
The cost of this
conversion is not high and depends mainly on the cost of the fuel pump. It
should take less than an hour to fit the pump and do the wiring (or longer if
you have a cool ale or two when mates come to see what
you are up to).
I hope this helps
someone.
Happy and safe
motoring
Joe Vavra
Australia