Those old fuel pumps can get stuck (lever not moving) at the high
point on the drive cam, and the check valves can also stay open so
that the fuel just moves back and forth. Given the age of the pump,
the first situation is not only possible, but I've seen it before.
Pump works by hand outside the engine, but there isn't enough
diaphragm movement installed to pump fuel. Shouldn't be a problem
with the new pump, but it's easy to install them so that the cam
doesn't move the pump lever, forgetting that it is pushed upward from
below rather than down from above.
On that engine, the lever sits on TOP of the cam, not underneath, and
it's possible to get the lever on the side of the cam when installing
it.
It is also possible that the cam is loose on the camshaft drive gear,
also a known problem from ages past.
The chain is the crankshaft to camshaft silent roller chain. They
are never really tight, but loose and sloppy can cause it to jump a
tooth, not a good thing.
Peter
On Apr 14, 2012, at 8:16 PM, MG wrote:
When you tested the fuel pump of the engine was the line to the
carb connected to the pump? Did you try the pumps on the engine
with the line to the carb disconnected? I'm thinking the line might
be plugged or the carb needle valve is plugged.
Manfred
Date: Sat, 14 Apr 2012 15:07:45 -0700
From: "Jerry Herrman" <jer...@san.rr.com>
Subject: [MBZ] Fuel Pump Not Delivering
Anyone out there with experience as an engine mechanic involving an
older Ford 390 engine, specifically the fuel pump?
This is on a '72 F250 I'm gonna get ready to sell. Last week when
it would not start, I disconnected the fuel line where it enters
the carburetor and found that the (mechanical) fuel pump was not
delivering gasoline to the carburetor. Knowing that the fuel pump
has been in there since at least 1978 when I bought it, and
possibly since new in 1972, I was suspicious that it had failed. I
bought a new (Carter) at Pep Boys and removed the old one (which
involved disconnecting the power steering assembly and moving it
aside). I then installed the new fuel pump and was disappointed to
find that it did not move the fuel either. I then attached a fuel
line to a container of gas and turned over the engine with the
starter. The new fuel pump would not suck up the gas.
I then removed the new pump and tested it by running the fuel line
into the container and moving the lever by hand. It sucked up the
fuel readily.
Then I hooked up the old pump to the fuel line and tested it by
hand. Lo and behold, it also sucked up the fuel just fine. This
told me that my old pump was still working. I reinstalled the old
pump and hooked it up to the container. It would not suck it up.
Jerry
82 240D
72 Ford F250
and others
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_______________________________________
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