'79 242 no start

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James Sweet - 05 Jan 2006 06:32 GMT

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.

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User - 06 Jan 2006 04:26 GMT

> 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
[quoted text clipped - 9 lines]
> 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

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James Sweet - 06 Jan 2006 05:04 GMT

> 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.

I disconnected the return line under the hood right near the fuel filter
on the firewall so there's nothing but a rubber hose between the fuel
distributor and that fitting. I verified the presence of fuel at the
filter by turning the pump on with that disconnected and got a healthy
looking flow. Should fuel come out the return line if I start the pump
without the engine running? I would think so, but I've never tried that
on a working car.

> 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,
[quoted text clipped - 12 lines]
> pressure.
>

I forgot to mention, the car does not have the original motor. This is a
Canadian B23E of unknown year that I installed which is complete with
the whole fuel system it came with. No frequency valve is present on
this particular setup though I've thought about installing the old B21F
injection system to hook up the lambda sond system.

> 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
[quoted text clipped - 11 lines]
> keeping the plunger from moving. If it is rusted or blistered it is
> finished and you'll need a different fuel distributor.

Thanks, I'll try this the next time I go out there and see what happens.

> 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.

It moves freely with the pump off, but sticks down with the pump
running. I haven't pulled very hard to see if it frees up though, I
didn't want to damage the delicate mechanism.

> 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.

I'm pretty sure this isn't the problem, as the flow plate feels fine
with the pump off, and it will run if I spray WD-40 into the airbox.

> Or it may just be dead gas.

Well the gas is certainly past it's prime, however symptoms point
towards something else, I'm just not sure entirely what. Thanks for the
suggestions though.

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User - 06 Jan 2006 05:38 GMT

> I disconnected the return line under the hood right near the fuel filter
> on the firewall so there's nothing but a rubber hose between the fuel
[quoted text clipped - 3 lines]
> without the engine running? I would think so, but I've never tried that
> on a working car.

The only things in the circuit that restrict return flow are the control
pressure regulator and the line pressure regulator. IIRC the line
pressure regulator puts about 5 bar+/- to the top of the fuel
distributor where it flows around the plunger to the bottom side of the
fuel distributor where it is regulated according to the temperature of
the bimetal strip inside to a pressure rising from 1.4bar to 3.7bar and
then whatever volume is left over with the injectors closed is bypassed
to the return line at very little pressure. So the answer would be yes.
Since the plunger is a spool valve the amount of return flow would
depend on the position of the plunger. Tap on the top of the fuel
distributor and see if it breaks loose.

Bob

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The goal when driving is to miss the maximum number of objects.

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