Good evening everybody,
currently, I’m getting a bit more of that old Jag wrenching than I really care for:
Some weeks ago I had an unhappy experience when the Jag engine - warm and running without choke - all of a sudden lost power. The engine would sputter, didn’t rev, but could be kept running. I was able to limp it back home, but had to cancel an appointment in Zurich as I didn’t dare to go on the motorway with a car in such condition. Some time later the engine resumed to proper functioning. As that hasn’t occurred again I thought it might have been the result of some water in the tank.
Unfortunately, it happened again yesterday and today. The malfunction is intermittent. Sometimes it occurs in a mild form, kind of strangling the engine but letting me travel on at like 40 mph, sometimes it is violent and then the car will barely creep on at like 10 - 15 mph with strong sputtering. I switched tanks with no immediate reaction. It seems to occur mostly upon marked changes of positions (once following a left turn, today when going through a trough), but sometimes just anytime. It’ll go on for some time until regular operation kicks in.
There is no visible smoke behind the car (at least not visible from the driver’s seat), there is no strong smell either. Twice I stopped and opened the hood to notice nothing impressive, again no smoke, no smell today. Last time I saw some fuel underneath the rear carb.
My initial thought (and feel) was fuel: the engine behaved as if it were flooded, but there was no black smoke nor any overwhelming fuel smell or puddles of fuel.
The symptoms might also occur if the engine didn’t net enough fuel - or one carb was not getting enough fuel. Typical rusty tank debris in carb scenario - but I have the standard fuel filter in the trunk and two additional fuel filters before the fuel pumps. Could it be an intermittent power out at the fuel pumps? I switched tanks to no avail and the pumps have individual grounds, so it could only be the power supply of the pumps upstream.
Finally, spark: a 1-2-3 ignition is installed that has performed flawlessly over the last 12 years. Is that a typical failure mode?
Any idea welcome!
Thanks as always
75 XJ6L 4.2 auto (UK spec)