I bought a 1985 XJ6 and had it checked out by a reputable Jag mechanic before purchasing. A few weeks after I bought it it started idling very rough and stalling when I was backing out of parking spaces or at red lights. I took it in for work and they adjusted the idle, which helped, but they really couldn't figure out the problem $600 later. It's much better but I can feel it's ready to stall out sometimes but hangs in there. The repair gave the car much more power up hills but it has stalled twice. Any ideas?

Submitted by dougdwyer@eart… on Sat, 02/07/2004 - 00:46

A few thoughts....

Since this seems to happen at idle or low-speed situations only, I would suspect a vacuum leak. Check all the hoses. Some are hidden under the inlet manifold and aux air valve. Make sure the connector boots of the air inlet system after the air flow meter are not torn or out of position.

Also check that the throttle blade has been set to .002" clearance and the area behind it has been "de-gunked".

A skewed coolant temp sensor can casue all sorts of weird things...only about $25 and 10 minutes to replace.

Are you getting black smoke from the pipes? If so, you have an over-rich mixture problem. A faulty fuel pressure regulator is fairly common and easily verified by checking fuel pressure (s/b 36 psi while cranking). The coolant temp sensor also can be a culprit if the engine is running too rich.

What work has already been done?

Post back if more info is needed regarding anything mentioned.

Good luck
Doug Dwyer
JDRC/NWA

Submitted by jam@ispwest.com on Fri, 02/06/2004 - 12:40

Hi:
I am not an expert at this but my '84 had the same problem until I replaced
the Fuel Filter, (did the $600. you paid include a new fuel filter?). it sounds like yours is starving for fuel intermittently, maybe an old clogged fuel filter?. (try Fram G3829 fuel filter for XJ-6 Series 3).
If not the fuel filter, then it sounds like an electronic sensor or fuel pressure regulator, or fuel pump relay, r even the fuel pump -Doug Dwyer and others here are the experts at this stuff-.

If replacing the fuel filter by yourself please note below:

**WARNINGS: Spilling of Fuel is unavoidable when changing the fuel filter, NO SMOKING, USE RUBBER GLOVES, COVER NOSE AND MOUTH, TAKE ALL PRECAUTIONS, FUEL VAPORS ARE TOXIC and EXPLOSIVE, WORK WITH A FAN IN HIGH SPEED TO VENTILATE FUMES AWAY FROM WORK AREA!!.

**you must de-pressurize the fuel system BEFORE diconnecting any Fuel System Component!! (all these warnings according to the Service Manual P.19-12).

To de-pressurize fuel system: On the passenger side, right side kick panel, below right Dash vent, there is a black plastic cover with a black Button on top, this black plastic cover is removable by pulling it, but do not use a screwdriver to pry it, then you'll see the de-pressurizing 'fuel pump socket' or 'fuel cutoff inertia switch'. (very confusing). Remove the wiring Socket from inertia switch, start the engine for 30 seconds, shut engine off and reconnect pump relay socket. Open both gas filler caps, leave open but over filler mouth;

Open trunk, remove floor carpet, wooden lid, spare tire, place disposable towels under/around old fuel filter in trunk floor, right front side of trunk, NOTE POSITION-ORIENTATION OF OLD FILTER COMPARING WITH NEW FILTER, use magic marker to mark the new filter with Date and Mileage installed, disconnect filter hoses, remove carefully, grab hoses with pliers gently and turn/wiggle filter back and forth, careful don't tear hoses, re-install new filter, do not over tighten or you can distort nipples, but do not leave loose either. A point of reference is to remember how hard you had to turn clamp screws to loosen them, then re-tighten the same way.

Hope this helps.