I have a 91 XJ40 Sovereign. A couple of weeks ago, I filled it up
with what I thought was bad gas. It started idling erratically and
it didn’t have any power. A couple of weeks later, after refilling
with with new gas, a new fuel filter, new distributor rotor, and
new spark plugs, it’s still driving extremely rough. The gas
consumption has dropped from about 21 mpg to 13.5 mpg.
Yesterdat, I tested spark plugs/wirings to see if there was any
arcing… the result was, yes, there was a healthy and consistent
firing from all the spark plugs (cylinders). Then, I performed
another test by pulling each of the spark plug wires while the car
was idling… lo and behold, pulling the first and second didn’t
cause a change in the idling. Pulling all the other spark plug
wires resulted in a change/slowdown of the idling. This told me
the first and second spark plugs were not getting any fuel.
Has anyone encountered this problem? What could be wrong? Bad
fuel injectors? Bad oxygen sensor?
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In reply to a message from EPG sent Tue 13 Dec 2005:
Assuming all your wires and caps are good and each cylinder is
getting a healthy spark at the right time, it must either be fuel
or compression problems (the famous triumverate). You could have a
bad injector harness connection, stuck or dirty injectors, or low
compression on the two cylinders (are they side by side by any
chance?). If it were mine, I would replace the distributor cap and
wires (cheap parts and they can be bad when still looking good) and
then start looking at the injectors. If all is well, run a
compression check on the two dead cylinders.–
Brian Caro 96XJ6 4.0 63E-TypeS1FHC
Newport News, VA, United States
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In reply to a message from Brian Caro sent Tue 13 Dec 2005:
If it were my car, I’d run a compression check first thing. I
doubt seriously that two of 6 injectors (or wiring, or anyhing
else) would fail simultaneously. But two burnt exhaust valves all
at once? I’d believe that, since it happened to me. It happened
climbing a long hill on the Interstate at around 70 mph. Halfway
up the hill, the car downshifted and began to labor. It was like
someone threw out the anchor.
I had 213,000 miles on the clock when it happened. Numbers 2 & 3
cylinders. All at once. Cost me a valve job. Took a week of my
evening labor, two valves and a gasket set.–
The original message included these comments:
chance?). If it were mine, I would replace the distributor cap and
wires (cheap parts and they can be bad when still looking good) and
then start looking at the injectors. If all is well, run a
compression check on the two dead cylinders.
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More likely bad valves or bad gasket. But you could have two sticky
injectors. Try a can of injector cleaner [two for a full tank of fuel].
Did you perform a compression test ?
Jay 90 VDP Majestic
EPG wrote:
I have a 91 XJ40 Sovereign. A couple of weeks ago, I filled it up
with what I thought was bad gas. It started idling erratically and
it didn’t have any power. A couple of weeks later, after refilling
with with new gas, a new fuel filter, new distributor rotor, and
new spark plugs, it’s still driving extremely rough. The gas
consumption has dropped from about 21 mpg to 13.5 mpg.
Yesterdat, I tested spark plugs/wirings to see if there was any
arcing… the result was, yes, there was a healthy and consistent
firing from all the spark plugs (cylinders). Then, I performed
another test by pulling each of the spark plug wires while the car
was idling… lo and behold, pulling the first and second didn’t
cause a change in the idling. Pulling all the other spark plug
wires resulted in a change/slowdown of the idling. This told me
the first and second spark plugs were not getting any fuel.
Has anyone encountered this problem? What could be wrong? Bad
fuel injectors? Bad oxygen sensor?
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In reply to a message from EPG sent Tue 13 Dec 2005:
EPG,
Did you listen to hear for the injectors clicking?
Remove the electrical connector from the two injectors, rig up some
test wiring…elecric meter probe wires work well…hook the wires
up to a battery…touch the probes to the injector pins, and see if
they click open.
It’s definitely not a bad O2 sensor.
SD Faircloth
www.jaguarfuelinjectorservice.com–
The original message included these comments:
wires resulted in a change/slowdown of the idling. This told me
the first and second spark plugs were not getting any fuel.
Has anyone encountered this problem? What could be wrong? Bad
fuel injectors? Bad oxygen sensor?
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In reply to a message from SD Faircloth sent Tue 13 Dec 2005:
take a comp test, if you have both cyls at 50 or 60 pounds, you
have burned head gskt. pajtas–
jaguarjoe 54 XK 120 rdstr 1961 MKIX 94 XJ6
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Brian: your symptoms sound awfully like a burnt exhaust valve. I’ve suffered
that twice, and the first time the symptoms were exactly as Pete
(jaguarpete) described. I’d have a compression test run on it. When mine
went the second time (No. 2 as opposed to No. 5 first time around), I could
hear a faint hiss or “pfffft” at idle right by the No. 2 cylinder.
Hope it’s something else, but I’m betting on a burnt valve or two.
Eliot Brenner
Annandale, Va.
89 XJ40 at 130.7k (and finally back driving again tonight after six weeks on
crutches. Gud Kity gets a run to Philly Wednesday, but perhaps slower coming
back Thursday because of impending nastiness. If it looks too nasty me and
Amtrak will be close friends.)
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In reply to a message from EPG sent Tue 13 Dec 2005:
Dont discount faulty plug leads, and also plugs (even if
they are new), and cap. Plugs can give what looks like a
healthy spark when removed, but under compression they can
fail. Similarly with leads if the resistance is too high it
will only fail under compression and when the plug is
removed from the cylinder, all sparks seem to be OK. Test
the leads with an ohmmeter they should all be in the
vicinity of 8 to 14000 ohms. Then look at the cap for signs
of tracking. Elimintion one by one is the only way.–
The original message included these comments:
I have a 91 XJ40 Sovereign. A couple of weeks ago, I filled it up
with what I thought was bad gas. It started idling erratically and
it didn’t have any power. A couple of weeks later, after refilling
with with new gas, a new fuel filter, new distributor rotor, and
new spark plugs, it’s still driving extremely rough. The gas
consumption has dropped from about 21 mpg to 13.5 mpg.
Yesterdat, I tested spark plugs/wirings to see if there was any
arcing… the result was, yes, there was a healthy and consistent
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