Several of you have contributed to my effort to restart my FHC after some
major/minor refurbishment this winter. It is amazing how one minor upgrade
leads to another, and another, and another until the simple project has
become complex.
In this case, everything was complete except the engine would not run. This
was especially frustrating because it was running very well in January when
the project started. After many false starts, the culprit turned out to be
burned points. Probably occured wen I left the ignition switch on while
chasing down a couple of electrical shorts in the new harness. Badly burned
but corrected now.
Then, of course there was the build up of carbon in the entire system from
multiple attempts at starting. New plugs and rough running for about 5
minutes cleared that problem. Even with very rough settings, it was a very;
satisfying sound.
But there is another problem that needs help.
Part of my winter project was to reinstall original “old style” carburetors
with the starting carb on the rear carburetor. It was sent to Joe Curto as
part of a rebuild and he checked it out and declared it “good”. And, yes,
it works. But it will not stop!!! Even when I disconect the ground wire.
Is the problem major or is it simply an adjustment of the setting on this
starting carb? It is impossible to do any adjusting to carburetor when the
system is on full choke.
I just did some work on my starting carb. It is my understanding that the
carb. is not engaged as soon as the control solenoid is in the closed
position and blocking the added fuel going to the intake manifold. Check
that the solenoid in the starting carbonator is working properly. If your
solenoid does not disengage when you disconnect the lead from your engine,
you have a solenoid problem. You can remove the solenoid from the car and
bench test it with a 12 volt power source. I found this to be helpful.
Check and insure the float valve and therefore fuel level in the
“serving” carbuerator is correct and is not “cver fueling” the starting
carb. In fact check to see that both carbs are functioning as ahey
overflow from the top, and an interim excessive level will give the same
symptoms as a partially open starting carb. If you are convinced they
are ok proceed with:
Disconnect the hot wire from the solenoid (starting carb coil) to insure
there is no internal ground that is holding the plunger up. Next, take
the unit to bits and see that the plunger is absolutely free to slide in
and out of the brass coil core, Next examine the brass stop washer to
insure it is free on the end of the plunger. Next check the units return
spring and insure that its coils are even and don’t interfere with the
plunger travel. IMHO, the starting carb works by having the solenoid
valve control the air (on or off) that “feeds” from an auxillary fuel and
venturi from the server. If the fuel level is “off” the unit may tend to
drown the engine>
Rick________________________________________________________________
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Thanks for the response. Lots of good progressive steps.
I’m at work and will get into the check list this evening.
Regarding the possibility of excess fuel. When I disengage the ground wire,
the plunger stays depressed. While there may still be too much fuel,
dosen’t the depressed plunger indicate a problem internal to the starting
carb?
It really sounds like I need to get into its inner workings. (Oh good.
Something more to learn!)
I’ll follow your suggestions and let you know what develops.
Ken;
By “ground wire”, do you mean the wire from the top of the
electromagnet to the otter switch at the forward part of the intake
manifold??
If so, I would look for some portion of the starting carb assembly
that is causing a complete circuit (grounding out) and causing the
electromagnet to “not” disengage. Double check to insure the coil to the
electromagnet wire is coming from the “SW” or negative side of the coil…
additionally, using an Ohm meter, check the Otter Switch for operation… it
should be “closed” (grounded) when cold and “open” (interrupted or off) when
the engine temp warms up…
If, when you disconnect the “power” wire (from the “SW/Neg” side of
the coil) and the electromagnetic plunger stays “engaged”, the I’d say
something is “binding” in the electro/mechanical portion of the starting
carb…
As we talked on the phone, I know very little about the starting
carbs, and the above is basically a guess.
I would be very interested in learning what finally “repairs” your
starting carb as my DHC was doing the same thing just before I disassembled
the entire car (I showed it, didn’t I? ;-( )
Charles #677556.
But there is another problem that needs help.
Part of my winter project was to reinstall original “old style” carburetors
with the starting carb on the rear carburetor. It was sent to Joe Curto as
part of a rebuild and he checked it out and declared it “good”. And, yes,
it works. But it will not stop!!! Even when I disconect the ground
wire.-----Original Message-----
From: Ken Hodge
Is the problem major or is it simply an adjustment of the setting on this
starting carb? It is impossible to do any adjusting to carburetor when the
system is on full choke.
What do you mean by depressed? The starting carburetor is a very simple
device. If depressed means that the plunger is drawn up, than you have your
wiring wrong. When the wire to the temp. switch is disconnected than there is
no current in the solenoid and the plunger drops down to cover the intake
pipe. The service manual has a good outline to follow.
You have got to explain “depressed”! Are you saying that with no
appearant complete circuit, the plunger is pulled into and retained by
the electromagnet? If so, disconnectthe source wire and see if the
problem goes away.
With no power to pull and hold the plunger, the disc must close off the
inlet pipe to the manifold. See that the plunger is free to move up and
down. There is no partial open as it either uncovers the inlet tube or
closes it off. It doesn’t go in stages. The disc or sealing plate is
not a perfect seal, but with gravity, the return spring, and inlet
vacuum, there isn’t sufficient air flow to draw an appreciable amount of
fuel.
Look to see that the electromagnet core is clean and the plunger travels
freely. See that there is no continuity from either coil connection to
the shell or center coil tube that might allow for the mysterious ground.
Good luck. and even if you do find there is an internal short, I think
you can carefully push out the electromagnet and rewind it rather simply.
Rick________________________________________________________________
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Rick;
I believe Ken isn’t referring to the electromagnetic plunger but
the brass metering rod instead… This is the same problem my DHC was having
when I last drove it…
Charles #677556.-----Original Message-----
From: holland-rick
Ken,
You have got to explain “depressed”! Are you saying that with no
appearant complete circuit, the plunger is pulled into and retained by
the electromagnet? If so, disconnectthe source wire and see if the
problem goes away.
Please “splain” about the depressed metering rod thingie as I dont
follow, I read that Ken had disconnexcted the ground wire (earth) and
thought the enrichening should have ceased.
How does the wire relate to the metering rod (depression)?
I need a beer, it’s hot and humid here, and it makes you almost forget
about women, fortunately there is AC and that "feeling only lasts a few
seconds every few days! Now I need a cigar too!
R________________________________________________________________
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Rick;
The “electromagnet” gizmo on the starting carb had a plunger,
spring and disk set-up that is energized by completing the circuit from the
coil to the otter switch… This unit sits “atop” the starting carb “pipe”
assembly…
Just to the right of the electromagnet (between the magnet and body
of carb) is a little brass rod that sticks-up about a half inch that goes
down into a “manifold” looking part of the starting carb set up… this is
the metering rod (correctly called the Auxiliary Starting Needle) I was
talking about… according to the SM, it is adjustable, apparently for the
starting carbs’ mixture… This metering rod can be manually depressed…
If I remember correctly, it is also depressed when the electromagnet
engages… In my case, the metering rod would NOT “un-depress” unless the
ign key was turned off or the wires to the electromagnet were disconnected…
In the case of my DHC, in the last stages of it’s driving days, I had
to disconnect the wire to the otter switch, raise the bonnet, manually
depress the metering rod and start the car from the solenoid button in the
engine bay… I then had to hold this rod down until the engine warmed up
enough to idle on it’s own…
That metering rod…
It's hot and humid here as well.. must be summer.. fortunately, our
temps are still in the low 90’s… no triple digits yet this year… in 1980
we had a record 80+ days of 100+ temps… 60 something in a row!!
Even the house A/C couldn’t keep up as it only “cooled off” to the
low 90’s at night My A/C in my XJ-6 would only bring the temp down to
the low '90s inside the car… that was one miserable summer!
Charles #677556.-----Original Message-----
From: holland-rick
Charles,
Please “splain” about the depressed metering rod thingie as I dont
follow, I read that Ken had disconnexcted the ground wire (earth) and
thought the enrichening should have ceased.
How does the wire relate to the metering rod (depression)?
I need a beer, it’s hot and humid here, and it makes you almost forget
about women, fortunately there is AC and that "feeling only lasts a few
seconds every few days! Now I need a cigar too!
Charles’ understanding of my explanation is correct. The only visible
evidence that the starting carb is working is a brass plunger that is sucked
down (depressed) while it is engaged. When the engine warms up, it is
supposed to return to its upper position. The selonoid activates something
that creates a vaccum and pulls the plunger down. Last night, if I would
manually pull the plunger up, the “choke” disengaged. When I would release
my hold on the plunger, it would return to the “depressed” position. If
something were binding, wouldn’t you expect the plunger to stay up and not
return to an engaged position?
I just took a break, ran home for lunch, and went straight to the garrage.
Turned on the ignition, and pulled the hot wire off the selonoid – spark
showed current flow. Disconnected the ground wire and touched the hot wire
to the post — no fire. Double checked everything.
So, if last night the starting carb did not disengage when the ground wire
was removed and there was no current flowing to it, the problem must be
mechanical. Right???
So, do you think that the adjustment that is available be so far off that
the carb will not disengage or do you think something is binding?
My 120 SE doesn’t want to know about the choke this time of year. Mine
is a manual/electrical toggle installed by the PO and it won’t start with
the choke on. I suspect that it’s tuned a might rich as I’ve relaced the
plugs once already and found several spares in the driver’s door pocket.
However, it runs well and as a veteran of the Motor Pool I’ve learned to
leave well enough alone.
It’s mechanical in that the solenoid and plunger allow the manifold
vacuum “exposure” to the outside ambient air via the 2 pencil size holes
in the base on the outer rim oft he sealing seat (this area is exposed
when the coil is removed from the base).
If the needle stays sucked down, I think youll find that the intake is
not closing off its air flow and the plunger is hanging up. There is no
linkage from the plunger mechanism to the brass needle. The two holes
that “allow” air into the manifold go up to the top of the casting that
the needle (depressed rod that you described) is housed in. Regardless
of the needle length, if you shut off the air, you also shut off the
fuel. If the needle is “sucked” down and stays so, IMHO you are
allowing it to have manifold vacuum and it might be sticky. If it pulls
dow on its own accord and you have to pull it up, (you) have somehow
(spring loaded it) arranged for it to go in the opposite direction!
It really is a simple rather well engineered device, but exceedingly
difficult to describe in text. BTW is the starting carb’s attitude
correct relative to the running carbs? It might be possible to have
mounted the unit below normal level by putting the cast feed fitting on
upsidedown or by spacing it too far below the float with a “banjo”
inbetween. Take a close look at the Svc Man to determine this. The fuel
level is critical to the starting carb too!
If it functioned ok before refurbishing and it fails now, more than
likely it’s something in backwards or left out completely.
Rick________________________________________________________________
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Binding. The metering rod is pulled down by the flow of air through the
hole in which it is centered. The solenoid controls the flow of fuel-air
mixture, just like a throttle plate. If the solenoid were closing off the
air and the metering rod were sticking, there would be no air flow, so no
enrichment (it’s not a choke, it’s a carburetor). If the solenoid were
sticking open then air would flow, rod would be sucked down, hiss would be
heard, and enrichment would occur.
I suggest that for whatever reason your solenoid is sticking open. Unsnap
it; it comes right off.
Mike Eck
New Jersey, USA
'51 XK120 OTS
'62 3.8 MK2 MOD
'72 SIII E-Type 2+2----- Original Message -----
So, do you think that the adjustment that is available be so far off that
the carb will not disengage or do you think something is binding?
So, do you think that the adjustment that is available be so far off that
the carb will not disengage or do you think something is binding?
I vote for adjustment.
Ken;
When my DHC started doing the same thing, it was "all of a
sudden"… I had not “just” re-done the carbs or had them or the manifold
off, nor had a “readjusted” the metering needle prior to this “event”
happening…
Otherwise I would agree with you about the adjustment…
I don’t think the metering rod is binding as it tends to “operate”
all to independantly of any known forces (X-Files-The Self-Engaging Starting
Carb)
Unless, and I defer to anyone that has intimate knowledge with the
starting carb set up, there might be something in the area where this needle
lives that is prone to wear that could cause this problem…
In theory, yours just having been gone thru by a qualified
professional, so I would rule out the “wear” factor as well…
BTW, for those thinking about it, my plunger, spring and disk in the
electromagnetic housing are visably near perfect…
Charles #677556.-----Original Message-----
From: Ken Hodge
I have been busy rebuilding a pair of carbs tonight so have only just come on
line. Sorry to hear about your problem.
The plunger in the solenoid is obviously remaining up when it should be down.
Rick has made the point, quite rightly, that you should check for mechanical
interference stopping it from falling under gravity/spring pressure. Next
check that when locating the solenoid, you have not trapped one or more coils
of the spring between the solenoid and its housing. easy to do.
However, I think the most likely cause is this. You said the starting carb
was attached to the rear carb. Therefore you have an early setup, maybe even
tall dashpots? The tall dashpots are irrelevant, but if you have an early
setup, you have the early solenoid, with screwdown terminals.
I have never known the later solenoid to malfunction, but the early type has
a top which is not rigidly connected to the body, so you get a bit of flexing
here. In addition to this, the way the internal wires are routed makes them
susceptible to chafing against the body. My guess is you have a short, with
the side which goes to the Otter switch occasionally grounding, which engages
the choke.
If the carbs have been recently rebuilt, the solenoid could well have been
disturbed. Check it out by disconnecting the Otter switch wire, then, with
the ignition on, wobble the solenoid around. Have a fire extinguished handy
as the solenoid is only a fraction of an inch away from the gas!
The solenoid does control the air flow but not quite like a throttle
plate. The throttle plate is variable over a range of air amounts,
whereas the solenoid disc valve is either open or closed. I suspect the
solenoid is stuck “up” (open) giving Ken an air draw thru the start carb
all the time, thats why his needle gets sucked down even with the coil
de-energized.
Rick________________________________________________________________
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There is nothing in the area where the “needle lives” that can cause it
to be drawn down unless outside air is “allowed” to enter via the pipe
opening. Its travel can be adjusted though, and that’s via the brass
adjusting nut that it passes through. there is a special spring steel
device that rests on a nut flat to keep it in adjustment. Fat fingers
more often than not, brake the the “tang” that forms the little u shaped
lock and the adjustment nut wanders.
The nut will affect how it runs under starting carb (rich,correct or
lean) not whether it engages.
Many folks don’t know how the carb works and turn the brass adjuster
breaking the tab off the retention spring and end up bottoming the nut
which, increases the needle travel and fuel ratio. Again the solenoid
air valve is critical to it’s on or off condition!
Most manual switch conversions don’t really care how the car runs with
the starting carb.
On these, the adjusters can be bottomed as these cars need only to have a
quantity of fuel “dumped” into the intake to permit the car to fire up
initially. Once started the solenoid is usually quickly shut off (no
Otter switch warm up) and the throttles are babyied to keep the car
running.
This is done because there are no “squirters” or accelerator pumps to
provide raw fuel and the annoying long delay awaiting for the carb to
shut down via Otter.
If you are using an “Otter” the carb must be adjusted to allow the engine
to both get enough fuel to fire, but not so much to soot the plugs and
“load it up”
If all the carbs are properly adjusted, the transition from starting carb
to only running carbs will not be descernable!
Rick,________________________________________________________________
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My A/C in my XJ-6 would only bring the temp down to