I'm finally getting around to working on my brother's '79 242 with CIS
injection. It sat for several months with a bad fuel pump so I replaced
the pump with a good used one. Car would then start and immediately die
unless I spray starting fluid into the intake in which case it runs
until that runs out. I thought the fuel filter may be clogged since it
was very old so I replaced that tonight, however I'm still seeing the
same symptom. If I disconnect the fuel return line and manually engage
the pump I can hear the pump load down as pressure builds up in the
line, however no fuel ever comes out the return. I also noticed that
with the pump running I can't lift the airflow sensor plate, I didn't
force it but it certainly doesn't move freely as it does with the pump
off. Anyone got ideas? I'm starting to wonder if the fuel distributor
has somehow got mucked up.
Ideas in no particular order.
Blow through the return line to make sure it is clean all the way to the
tank. The metal lines can be damaged if someone just jams a jack under
the center of the car and tries to lift it NASCAR style.
The 4cyl motors use an upflow fuel distributor, the 6cyl use a downflow.
So lifting up the plate should make the injectors spray on a 4cyl,
pushing down makes the injectors spray on a 6cyl.
I think that '79 was the first year of the "small" airflow sensor plate.
If so, the line pressure regulator and control pressure regulator check
valve share the same horizontal bore in the fuel distributor. In additon
to the spring and shims on the needle valve there is a small o-ring that
can leak and make the car very hard to start. It can stick but not very
solidly. If it has a frequency valve then when the valve is in the
default shut position there will be no flow. It may not be running when
you jumper the fuel pump relay and there would be no flow on the return
side of the circuit. If you can break the line loose at the fuel
distributor however there should be fuel present but very little
pressure.
Pull out an injector so you can see what is happening. Jump the fuel
pump relay so that the pump is running. Pull the intake bellows out of
the way and grab the 10mm headed screw in the middle of the air flow
sensor plate and lift. The injector should spray. If it doesn't try
rapping on the center of the fuel distributor to see is the plunger
comes unstuck. If not delete all the above steps then pull the fuel
distributor off. Be sure to keep track of all the little copper seals.
You will need them again. Ideally they should be replaced but we're
testing here. Keep track of all the plastic screens/valves in the
vertical outlet ports and the rubber o-ring between the fuel distributor
and the airflow housing. Carefully pull the plunger out of the bore in
the center. Note the orientaton of the plunger as you remove it. Clean
it and the bore with carburetor cleaner to remove any varnish that is
keeping the plunger from moving. If it is rusted or blistered it is
finished and you'll need a different fuel distributor.
Make sure the arm for the airflow sensor plate moves freely in the bore.
If it needs to be recentered you can put three 0.002" feeler gauges
around the edge of the plate and then loosen and retighten the center
screw.
Another possibility is that creatures have shredded the air filter and
built a nest in the air box that got sucked into the bellows tube and
may be interfering with the operation of the counter weight on the air
flow sensor plate arm.
Or it may just be dead gas.
Bob
