Hello All,
I started on the PI metering unit on my 2.5 saloon today so, just for
your interest's sake, here's a quick run through what I found.
The symptoms of the car's problem were apparent richness, giving a
regular misfire and rough running, and a tendency for the injectors to
be blocked with what seemed to be bits of black, rubbery seal material.
The metering unit came off fairly easily, although the main fuel inlet
union nut was very tight and needed an application of boiling water to
get it to move ( I haven't yet removed the inlet union) . After cleaning
down and labelling, I removed the pipes and unions (two are O-ring
type). The vacuum control unit was also easy to strip although the
roller link assembly was reluctant to come out upwards.
Then, I hooked out the sleeve seals, removed the stop and circlip and
pushed out the sleeve.
Findings so far....
Rotor, stop and sleeve in excellent condition-no scoring and virtually
no marks.
MU body marked with a hand-engraved/scratched-in number and a roughly
punched-in 'X'. Internal machining very poor but O-ring lands fine.
Some sort of non-return valve in each union-appear in good order.
No apparent degradation of the sleeve seals, although they are markedly
flared, to the extent of having a flange which the new seals don't have.
Fuel control diaphragm has concentric cracks which are not quite through
the material.
The diaphragm follower appeared to be seized or partially seized in the
vac chamber wall. When I took the rotor housing off, the spring did not
force the follower out.
The rotor end float is 24 thou.-there is no apparent wear on the brass
thrust plate.
So, I wonder where the black stuff is coming from? Clearly not the
seals.
Also, I'm not sure if the unit has not been exchanged at some point;
clues: the markings above, the condition and the presence of: slotted,
hex headed set screws on the rotor stop, hex headed sets holding the vac
chamber and rotor housing together, no Doughty seals.
Incidentally, I also found the fuel leak. The line from the filter to
the pump is partly that nasty, nylon string reinforced plastic fuel line
and partly proper black line, fitted on either side of a brass, push fit
union. This joint, although fitted with clips, has been weeping and will
no longer seal.
I've also removed the injectors which are to be sent away for
professional calibration.
That's it for now. Any comments, queries or tips?
Cheers,
Dave Hill
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