CIS troubleshooting

[Graham Thackrah]

Hi List,

Any pointers gratefully received.

My 1985 UK 90 quattro with CIS basic (after Probst) doesn't start. All the
ignition components check out fine (coil resistance, hall sender, and
ignition control module all pass the tests outlined in Haynes). You can
pull plugs, ground them and they have nice juicy sparks when you crank the
engine too:)

I just got hold of a FP guage and system pressure is just a bit below 5
bar. Cold control pressure was above 2 bar though, and I think this is
supposed to be lower (1.5 nominal?), it was about 10 celcius when I tested
it, and the engine was stone cold. With the ignition on but the car not
running control pressure rose slowly to about 3.5 to 4 bar. Does the
heater in the warm-up-regulator need the engine to be running, or just the
ignition on? Before I tried that it seemed that control pressure was
slowly rising anyway, with no power to the warm-up-regulator, could I have
been imagining that or is it supposed to do it?

When control pressure regulators fail, do they fail and give a higher or
lower than spec control pressure, or does it depend on their mode of
failure?

I can see if the cont. press. is too high then the car would be running
too lean to start, but my car doesn't make _any_ attempt to start, no
stuttering or anything. I pulled the FP relay and opened it up to find
some dodgy (tm) looking contacts there, possibly shorts, so it could be
that causing my troubles, should the car start with the FP jumpered and no
FP relay fitted? Also, would it be ok to refit the FP relay without its
cover and see if it flips ok when starting? Or should I just check the FP
gets 12V on cranking with the relay in place?

After stopping the pump, the residual pressure is just below 3 bar, which
I think is ok, and it kept this for at least 5 mins, the fuel pressure
accumulator is certainly not marginal.

I also think I checked all my air/vac hoses too (its got new vac lines
throughout, only the breaters are not new but I think they're ok), even
put hose clamps on some that never had them before when the car used to
run. I also just replaced all the seals and seats on the injectors (the
old ones were very marginal), but didn't check the spray pattern of the
injectors, or even if they sprayed at all. Of course, I could have fixed a
huge vac leak at the injectors and now the car's running too rich to
start...!!

With the air intake boot off the air metering plate doesn't stick if you
lift it and you can feel residual control pressure resisting its upward
movement, when you drop it it bounces once or twice then comes to rest.

When you crank the engine the cold start valve fires a lovely text book
cone of fuel, but I didn't check if it stopped after c. 2 seconds.

There is fuel in the tank too;)

Any other ideas? My first priority is to confirm the FP relay is ok, so I
may try and replace it with a known good one and see if it makes any
difference.

Cheers in advance,

Graham.

P.S. Hi Paul, hope you remember this, sorry it took me so long but I ended
up shipping JCWHitneys FP guage over as you can't get FP guages for much
less than several hundred pounds over here, and no, don't ask how much it
cost to do that, it was still cheaper... just! I also got a copy of
Probst, and got the basics, but I'm still totally stumped with this one.