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tabasco tabasco is offline
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Join Date: Apr 2008
Location: Houston, TX
Posts: 306
I had a similar issue when I started my car after sitting a few years, the fuel return line was clogged at the tank.
So the control pressure was building up and the car was running incredibly lean.

Find a CIS pressure gauge, and measure your pressures.

If you want to know more about CIS and how it works, here's a good start :
911 CIS Primer - Index

You can also do a quick diagnostic without a gauge : remove the air filter housing and push down on the metering plate to see if it moves easily. The fuel pumps must be running, so jump both relays.
Don't do push on the measuring plate too long as when you do that, your injectors fire and you don't want to flood your cylinders with gas !
If the plate moves easily, your problem is probably upstream : not enough fuel coming (fuel pumps, filter, pressure regulator, ...).
If the plate needs more than light finger pressure to move, your control pressure is too high : clogged lines, clogged warm up regulator, ...

But get a CIS gauge anyway, you need one !

Old 12-22-2014, 11:18 AM
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