Hi all, I have some confusion over the workshop manual. The 83 Mondial is running too rich. Control pressure and system pressure were the same at 4.9. WUR return line drained only a dribble of fuel into a jar with pump running, so I shipped off the plugged up WUR for rebuild. I would have thought such high control pressure would make it run lean, but black fuel smelling plugs look pretty rich to me, so something else may well be wrong. Car starts easily warm & cold, pulls strong and drives smooth in all gears, but won’t idle for more than a minute or two warm or cold. The workshop manual states that the air metering plate should spring back with a bit of a bounce, which it did with a bit of residual fuel pressure, but does not spring back without the WUR. No mention in the manual of needing fuel pressure for this test. Is there a spring to push up the plate in absence of fuel pressure? Thanks, Phil
Thanks for the reply. According to service records, the fuel distributor was apperently rebuilt less than 300 miles and five years ago, along with belts and new injectors, but then sat for 3 years. I drained out some pretty foul smelling gas. Amazing to see how fast old fuel can ruin the CIS.
Ethanol or corn alcohol is the culprit. I seriously doubt the previous owner used ethanol free gas and you have a CIS fuel distributor that is full of varnish and gum.
This should mean that some gas tank additives could dissolve the deposits, right? So, mount a steady assault with double dose tank additives?
The Techron certainly did help smooth out the mid range power, but not the idle. The warm up regulator was dirty and visibly plugged with varnish, and was shipped out for rebuilding. The rebuilt fuel distributor filters and passages look super clean, and plunger moves freely. The parts diagram shows a small spring on the air flap hinge, but doesn’t show what the spring acts on or does. Does the air flap spring back without fuel pressure?
The fuel distributor has a very delicate metering system in it and from my experience techron or any other fuel cleaner will not fully dissolve the gummy residue. It loosens up the gum and the particles get caught in the fuel distributor. The other problem that comes with ethanol is the corrosive nature and it causes the rubber diaphragms to split inside the fuel distributor causing large amounts of gas to enter the cylinder....too much to ignite, then it gets pushed out the exhaust system and you start to see brown gas coming out of the exhaust catalytic converter system. Sometimes the cat will burn up due to the excess of gas, so keep an eye out for a glowing catalytic converter. You need to have the fuel distributor re-built. Dont waste your time with fuel additives and cleaners.
JK, is it possible to pull the FD and check the rubber diaphragm (I haven't even looked where it is located -- just gathering info). Thanks.
