[xj40] Rant: another electrical issue? (no-start)

XJ40
1

I was feeling good about having found the source of my
battery drain (a recent forum thread: I removed the lock
heater relay and the drain went away). Drove the car about
15 miles yesterday to have lunch with a friend. When I went
to leave about 90 minutes later, the car wouldn’t start. It
would crank like crazy but not even a cough.

The tach wiggled slightly as I cranked so I assumed I had
spark. I tried to hear the fuel pump run when I turned the
key on but couldn’t (hard to tell over the blare of the
warning horn and the noise of the attack belts running). I
removed the fuses for the attack belts, still heard nothing
but the warning horn. I happened to have a Philips
screwdriver in the car so I removed the passenger knee panel
and tried swapping the fuel pump relay with another one. And
another one. Still no start (altogether probably 12+ tries
over a 2-hour period, battery still strong, no console
warning panel clues). Not a lot more I could do alone and in
my good clothes. Debated whether to call a local junkyard
and have them come get it (this crap is getting tiresome).

Finally gave up, called AAA and had it towed to the shop on
a flatbed truck.

Shop called today and said he’d installed a fuel pressure
gauge and no fuel spilled out while he attached it (it
normally would spill some, so that’s a clue it might be a
fuel pump issue). Then he turned the key on and the pressure
reading went up to normal. He turned the key to Start and
the the car instantly started. It probably would have
started when the tow truck dropped it off, I’ll never know
for sure.

So, now I have an intermittent failure, likely electrical
and if I drive it, I may end up having to have the car towed
again.

Arrrggghhhh!–
84 XJS, 89 XJS, 89 XJ40
Santa Barbara, CA, United States
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2

In reply to a message from WayneC sent Sat 12 Mar 2011:

Wayne,

I hate those intermittent problems which mysteriously cure
themselves without giving us a clue as to what the problem was!

When I read the first paragraph of your post, my immediate
reaction was ‘Aha! a hot start problem’ - the one where the
‘hold pressure’ in the fuel rail is not maintained after
engine shut-down and the sudden drop in rail pressure on a
hot engine causes a ‘vapour lock’ type of situation thus
preventing the next start. My car did exactly that after
leaving it for about the same time as yours and I had to
employ the ‘key-cycling’ trick before there was enough
pressure in the fuel rail from the priming burst each time
the ignition was switched on to allow the engine to fire.

Did your mechanic check that the system was holding fuel
pressure after he switched off the engine? I solved the
problem by replacing the fuel pressure regulator but equally
it can be caused by a failure of the check valve in the
outlet of the fuel pump. (Easy to replace on your car with
the external pump).

Try the key-cycling trick if it occurs again - switch the
key ON-OFF-ON-OFF-ON … rapidly 6 or 8 times before
cranking the engine until after the final ‘ON’.

When you say ‘‘The tach wiggled slightly as I cranked …’’
Do you mean it registered 200 rpm or thereabouts? Even with
a dead CPS (and they can be intermittent) the tach needle
will bounce on its stop as you crank, but if the CPS is
good, you should see a positive reading on the tach.–
The original message included these comments:

I was feeling good about having found the source of my
battery drain (a recent forum thread: I removed the lock
heater relay and the drain went away). Drove the car about
15 miles yesterday to have lunch with a friend. When I went
to leave about 90 minutes later, the car wouldn’t start. It
would crank like crazy but not even a cough.
The tach wiggled slightly as I cranked so I assumed I had

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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3

In reply to a message from WayneC sent Sat 12 Mar 2011:

Wayne. If it is the original pump in the 89 and your outside temp
was above 75degrees it needs to be replaced it has started
to ‘‘flutter’’ as Jaguar and Haynes discribe this fault. When the car
cools down it will run fine again until the next hot day and if you
park it in a black asphalt car park the radiant heat makes it
happen quicker. John.–
John. Walsh. Purrrrr 89 vdp
bowmanville ontario, Canada
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4

In reply to a message from WayneC sent Sat 12 Mar 2011:

If your fuel pump is original, you should replace it. The pump is
actially an electric motor with commutator and brushes. It runs
submerged in gasoline, which is not a good lubricant. I’ve got
photos of what’s inside in one of my albums.
When the commutator wears the way mine did, the motor may slow down
or become erratic. The pump it drives is a little positive
displacement roller pump that needs a good level of fuel above it
for proper operating (I’ll bet your tank was less than half full
when it wouldn’t start). But there’s another cotributor to a no-
start issue in hot weather – tank breathing and the evaporative
emissions system.
When the engine comes to temperature, a small thermostatic vacuum
vlave opens to put intake manifold vacuum on the charcoal canister
to purge accumulated vapors the cannister absorbed from the fuel
tank. to get a flow, you need outside air flowing into the fuel
tank (there are two small hoses that allow air in. They poke
through the trunk wall in the space behind the differential). If
the hoses are plugged, a light vacuum is created in the fuel tank
and the lower pressure can cause the fuel right at the suction of
the pump to boil to a vapor. When that happens, the pump loses
section and the engine will not run.
Once it all cools off, it’s as if nothing happened. Next time
you’re under the car, note that the fuel line to the pump is
wrapped with aluminized insulation to protect the hose from the hot
exhausts and differential nearby.
Interestingly, Mazda just issued a fuel system recall notice about
little yellow spiders that like the smell of gasoline and can build
their nests and webs inside tank vent hoses in some of their cars.
The solution, of course, is to poke a wire in the two hoses under
the car and clear out the restrictions. But a short-term fix is to
simply loosen the fuel filler cap the next time it happens to you.
You will probably hear a great ‘whoosh’ when you loosen the cap.
But the car will start and run.–
The original message included these comments:

another one. Still no start (altogether probably 12+ tries
over a 2-hour period, battery still strong, no console
warning panel clues). Not a lot more I could do alone and in
my good clothes. Debated whether to call a local junkyard
and have them come get it (this crap is getting tiresome).
Finally gave up, called AAA and had it towed to the shop on
a flatbed truck.
Shop called today and said he’d installed a fuel pressure
gauge and no fuel spilled out while he attached it (it
normally would spill some, so that’s a clue it might be a
fuel pump issue). Then he turned the key on and the pressure

–
Pete Peterson 70E(193K) 88XJ40s(253K & 242K) 94XJ40 (122K)
Severna Park, Maryland, United States
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5

In reply to a message from Jaguarpete sent Sat 12 Mar 2011:

Good suggestions, guys.

The temperature was moderate when this occurred (perhaps low
70’s), and the car had hours to cool during lunch and while
I was trying to start it.
My car has an external fuel pump, likely the original.
The car has about 155k miles, 60k by me. The tach barely
wiggled during cranking, perceptible but not pronounced; I
doubt it got anywhere near 200 rpm. The CPS was replaced
once during my ownership, and the car has perhaps 30k or 40k
miles on it since then. More likely something jiggled when
the car was being towed, although that doesn’t really
explain why it went bad just parked, so the hot-soak
argument is also a possibility though I wouldn’t expect it
to last several hours. The mechanic thought that the fact
that he got no fuel leakage as he placed the pressure gauge
meant it likely was a fuel pressure issue rather than
ignition. He suspects fuel pump, but is reluctant to replace
it without knowing for certain due to the cost ($300 his
cost, $500 retail for the pump purchase). He knows I’ve
gotten exasperated with these cars in recent months …I’ve
spent a lot of money and time with him, we’ve become bosom
buddies over the years :>)

My post was more of a rant than anything else. I’m just
getting exasperated, as I own 3 Jags and it seems the
problems are coming at me faster all the time, and I’m
getting too old to cope. I spent hours a few days back
trying to fix door latch problems on this same car for the
umpteenth time (before, during, and after the battery drain
issue). I’ve worn out all the door trim fasteners taking the
doors apart and putting them back together so many times
:>). I have 3 ‘‘sticky latch’’ outer door handles and one back
door that requires use of the inside handle… I’ve been
fighting those issues for years, even replaced the front
door handles once; one time I spent many hours getting the
door latches adjusted just so, all working perfectly and the
next day I went to the airport to pick up some visiting
friends and the passenger door and one rear door wouldn’t
open, even with the inside handles!). My mechanic won’t work
on latches, for the reasons I mention, it takes a lot of
time (money) and often the customer is back again the next
day with the same issues.

My other 2 Jags are XJS coupes, one with a cycling inside
door handle that drains the battery, a mysterious loud
cracking sound occasionally emanating from somewhere forward
of the right door, and an A/C that needs recharging (this
car only has 20k original miles); the other (85K miles) has
developed a serious leak in a seals on a recently-installed
steering rack, and a front end looseness/harshness/noise
(heard and felt in the steering wheel when traversing bumps)
that nobody can find (ball joints & shocks also recently
done, by me personally).

I’m always concerned none of the 3 Jags will be drivable
when I leave the house to go somewhere.

I love 'em but I need to divest myself of some of these
cats, I can’t keep up with their issues–
84 XJS, 89 XJS, 89 XJ40
Santa Barbara, CA, United States
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6

In reply to a message from Jaguarpete sent Sat 12 Mar 2011:

Pete

My 87 XJ40 has always made a great whoosh when unscrewing the
petrol cap (unless tha tank is approaching empty). I never thought
there was anything amiss…–
The original message included these comments:

You will probably hear a great ‘whoosh’ when you loosen the cap.
But the car will start and run.

–
Alan (XJ40 3.6L 1987/8)
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7

In reply to a message from Alan4d sent Sun 13 Mar 2011:

It depends on which way the air rushes. Does it blow out of the
tank? In which case your evaporative emissions system may not be
working as it should. There are pressure relief devices in the
circuit to prevent the pressure from building past 2 psig.
If it sucks in, it can cause fuel starvation or, worse, a collapsed
tank.–
The original message included these comments:

My 87 XJ40 has always made a great whoosh when unscrewing the
petrol cap (unless tha tank is approaching empty). I never thought
there was anything amiss…

–
Pete Peterson 70E(193K) 88XJ40s(253K & 242K) 94XJ40 (122K)
Severna Park, Maryland, United States
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8

In reply to a message from h s law sent Sat 12 Mar 2011:

Outside the fuel tank as well, easy replacement when up on a
lift. Can be done on jack stands, just get it up high
enough. Replace your fuel pump.–
mrtalkradio
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9

In reply to a message from Jaguarpete sent Sun 13 Mar 2011:

…but the car runs fine Pete (when it hasn’t got the top off as
you know!) It’s been doing the whossh (ouwards I think) for years.–
The original message included these comments:

In reply to a message from Alan4d sent Sun 13 Mar 2011:
It depends on which way the air rushes. Does it blow out of the
tank? In which case your evaporative emissions system may not be
working as it should. There are pressure relief devices in the
circuit to prevent the pressure from building past 2 psig.

–
Alan (XJ40 3.6L 1987/8)
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