Jaguar XJ-S. Service manual — part 63

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can see! Treat the entire tank the same way, and then you can conclude that the entire tank is done when the visible
areas look done.

When the liner is poured in, you need to slosh it around to coat all the inside surfaces and drain out the excess. Good
luck! First off, the stuff doesn’t really “slosh” since it’s a little too thick; it might help to dilute the liner with some
MEK or acetone prior to pouring it in. Even if you render it sloshable, it’s still difficult to coat all those internal baffles;
as you rotate the tank over and over, the fluid pours past the baffles without really getting up on them. Of course, the
baffles are not a leak concern, but you would like to prevent them from rusting anyway.

When you open the tank up to drain the excess liner, you can just prop it up and let it pour out -- and it’ll pour for two
hours. Alternatively, you can just drain for five minutes -- getting most of what you will ever get out -- and then tip the
tank over to let the remainder run back across surfaces inside to make the coating a little thicker. If you will tip the tank
to a different position every few minutes, you can avoid the lining puddling in any one place.

Of course, while you’re lining the tank, it would also make sense to line the surge tank -- which is easier to do, although
again it’s not as easy to drain as you might think. The drain plug in the bottom won’t drain the lowest half inch of
liquid! You have to tip and tilt the surge tank to get everything to drain out of the big pickup opening, and all the
liquids like to flow around the opening rather than draining out it.

And you might also want to consider lining the vapor separator, although it’s a bit tougher because the biggest opening
into it is a 5/16” hose connection.

If all this sounds like too much for the do-it-yourselfer, there are places that will do it for you. You can usually find a
local shop that does this sort of work, although the one found by the author had never heard of phosphoric acid, had
been applying liners over bare metal with surface rust for 25 years. For a more reputable shop, you can contact
Moyer’s Fuel Tank Renu (page 701) about shipping your tank to them for work.

Although this section was written with the XJ-S coupe fuel tank in mind, it’s probably equally applicable to the
convertible and cabriolet. The Hess & Eisenhart is another animal, since it has two tanks; the upper one is a modified
version of the coupe tank and the lower one is completely custom.

FUEL TANK COATING: As mentioned above, a common cause of fuel leaks in the XJ-S is rust on the outside of the
tank -- specifically, the bottom. Therefore, even if you’re not interested in lining the inside as described above, you
might want to tackle the job of making sure the outside doesn’t rust. The tank still has to come out, but beyond that this
job is obviously much easier. Simply clean off any existing surface rust (and possibly the paint if you want, meaning
you can sand-blast the whole outside if you wish), treat it with a phosphoric acid product such as Ospho or Naval Jelly,
and then coat it with something that will make really sure it won’t rust. Automotive undercoating is a popular idea, as
is POR 15. Undercoating is available in spray cans from automotive stores. You can’t see the tank after it’s installed,
so appearance is not an issue; you just want to make very sure it will never rust again.

Note: when you first remove the carpet and look at the tank in place, what you may think is rust may be the remnants of
the glue that once held the carpet in place. Be sure you’re really looking at rust before you panic.

FUEL TANK REPLACEMENT: The author, having gone through the tank lining process, has arrived at a few
conclusions:

1) I’d never do it again. Rather than fiddling around with all this work, I’d just take the tank down to a local fab shop
and have them make me an entirely new tank out of heavy gauge aluminum. The cost is reportedly comparable to
buying a new tank from Jaguar, but if you buy a new tank from Jaguar you still end up with a rust-prone steel can.
While making the new aluminum tank, I’d omit those stupid threaded compression fittings and just provide barbs for
connecting hoses. I’d probably have a new surge tank made while I was at it, and completely change its configuration
so as to better locate the pump and an in-hose pickup filter.

2) I consider the entire idea of making automobile fuel tanks from steel to be irresponsible at best. Aluminum should
be the minimum specification, if only to minimize rust problems. From an automobile manufacturer, though, I would

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expect a mass-produced version of the fuel cell commonly used in racing. Racing organizations wouldn’t consider a
simple steel tank acceptable, and with good reason: they’re an obvious fire safety hazard. It wouldn’t cost auto
manufacturers $20 more per car to provide a similar level of safety in street cars -- far less than air bags or ABS brakes
cost.

FUEL LEVEL SENDER: It’s discussed on page 592.

Fuel Tank: Hess & Eisenhardt Convertible

FUEL TANKS: This section is of no use to coupe or later convertible owners, but it is reportedly difficult for H&E
owners to find information on how this system works so a description is included here. According to Mike Cogswell,
“In order to make room for the folding top and its mechanism H&E had to take the standard tank and cut part of it off.
It would appear they literally cut the tank and welded in a sloped section. To regain fuel capacity, they added a second
tank under the parcel area, basically where the rear seat would have been in a coupe. The upper tank is about 14 US
gal. and the lower is about 11.

“As you know, the standard tank has a sump from which the high pressure fuel injection pump draws its fuel. Since the
second tank is lower than the first H&E added two concentric hoses. The larger outer hose allows fuel to gravity drain
into the lower tank from the upper (which is where the filler neck is located.) Consequently, the lower tank is always
full until the upper tank goes dry. Meanwhile, a small submerged pump constantly pumps fuel from the bottom tank to
the top tank via a small tube that is located in the center of the large drain hose. The fuel is dumped into the upper
tank’s sump, where it is available to the main fuel pump. The submerged pump can pump fuel faster than the engine
consumes it, but any in excess of the sump capacity will drain right back into the lower tank. Both pumps only run
when the ignition is on and the standard pump circuit is energized, so all the regular safety interlocks still work.”

Tim Blystone points out that since parking the car nose-down on an incline will cause the fuel to drain toward the
forward tank and away from the sump, the auxiliary pump might not keep up when the tank is less than half full. “All
of the early tank designs will stall on a sufficient incline.”

“H&E went through a couple of different configurations. The main difference is the dams added in the interior of Jags
original tank.”

FUEL TANK LEAKS: This author has only laid eyes on one H&E convertible, and that one was literally pouring fuel
out the bottom of the car. Steve Wilke says, “I've heard stories from a couple of informed sources that Jaguar Cars
repurchased a large number of Hess & Eisenhardt convertible conversions, and these cars were then shipped elsewhere;
Brazil was one of the target countries that was mentioned to me. Seems that a large number of the H&E conversion
fuel tanks weren't made properly, and had a propensity for splitting their seams and producing a very pronounced fuel
smell. When the owner would call the dealer to report this, they'd say something like "Really? Where is this Jaguar?".
Then they'd send over a flatbed truck, load up the car, and hand the owner a check. Perhaps Brazil has a much lower
population of suit-hungry attorneys than the States do. I would expect the population of H&E's in the States to be quite
small indeed by this point.”

If you have an H&E with a leaking tank, there’s certainly no need to ship it to Brazil. It’s a fairly simple matter to fix a
leaking fuel tank, or even to simply take it to a local welding shop and have them fab up a replacement tank in heavy-
guage aluminum with whatever fittings and connections you desire.

FUEL GUAGE: see page 593.

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FUEL HEATING PROBLEMS: The stock Jaguar fuel pump moves far more fuel than the engine normally needs with
the excess returned to the tank. Since this heats the fuel somewhat, a fuel cooler is included in the return line, using the
A/C freon circuit to provide cooling. On the H&E, however, the problem is exacerbated by the fact there are two
pumps running full time, coupled with the fact the car is a convertible so the top may be down and the A/C off on warm
days! Tim Blystone: “Normally this presents very little problems until the A/C goes on the fritz, or you have one of
H&E’s earlier designs. If it is summer, the top is down... the A/C system is off. No cool fuel. Vapor lock from hell.”

FUEL SYSTEM MODS: Tim Blystone: “My modification puts the plastic hose from the H&E fuel cell directly into
the supply for the sump tank. A new and longer piece of hose is required. Fuel is pumped by the H&E pump directly
into the Jag sump tank and bypasses the need for the tank to be gravity filled. There is a return to Jags original main
tank from the sump tank so there is no excess pressure in the sump. The result is a fuel system that doesn’t have the
H&E problem with steep inclines or die dead in the middle of a hot southern day.”

Another idea might be to do away with the surge tank and main fuel pump altogether and (somehow) connect the pump
in the lower tank directly to the engine. The fuel in the upper tank can then simply gravity-feed to the lower tank and
stay there. Basically, the lower tank would serve as the surge tank. The return line from the engine doesn’t require
alteration, it can continue to feed into the upper tank. The vent lines from the surge tank can simply be plugged,
allowing the existing vent lines from the two main tanks to work as intended. Benefits include more luggage space in
the trunk! Before doing this, one would need to ensure that the fuel pump in the lower tank can actually provide the
flow and pressure required by the engine. If necessary, just replace that pump with one of known capacity -- one from
any large V8 with EFI, for example.

GAS CAPS: The single gas filler on the H&E is the same as the two on an XJ6.

Surge Tank and Fuel Pickup

FUEL PICKUP: Leonard Berk’s XJ-S would run fine when first started, but after a half hour it would start to lose
power, eventually coming to a stop. After shutting it off and letting it sit for a minute, it would start and run fine for
another half hour. It turned out the problem was dirt in the small surge tank in the trunk. As the engine ran, the dirt
would gradually collect on the screen on the pickup and plug it. When the engine was shut off, the dirt would fall back
to the bottom of the tank. This is not a freak occurrence; in fact, it is one of the most common failure modes on the
Jaguar XJ-S! This same problem happened to this author’s ’83 and several others have reported it as well.

In fact, it’s common enough that it even caught Jaguar’s attention. This pickup screen plugging is a very rare example
of a problem that has been recognized and addressed by Jaguar. In Issue No. 2 of the XJS Bulletin, Ray Ingman of
Classic Spares, Inc., reports that Jaguar issued a replacement pickup screen with a considerably larger screen area. The
part number is CBC5649. Anyone working in the area should definitely upgrade.

Ingman apparently doesn’t think a lot of this fix; his impression is that the larger area won’t prevent it from plugging,
it’ll just take longer. He may be right, but he might not be. For one thing, the suction at the screen is a function of the
screen area, so a screen with more area will have less suction at the surface -- so maybe the junk won’t have as much
tendency to stick. Another possibility: It may be that the larger screen has so much area that it's effectively
unpluggable -- you could cover the entire surface with crud and it would still be able to pull enough fuel through the
nooks and crannies between chunks to maintain flow and keep running.

John Goodman owns a 1989 XJR-S 6.0 litre: “I have just cleaned out my sump tank, no signs of a filter!” Who knows,
maybe Jaguar decided it was more trouble than it was worth.

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There is some experience to indicate that the plugged pickup problem is often accompanied by a failed fuel pump.
Perhaps the plugged pickup causes the pump failure. Be aware that when you find the pickup problem you may also
have to replace the pump before the car runs right again. Apparently, if you can hear the pump whining when driving,
you can count on it. Perhaps the cost of this pump is one good reason to check the pickup before you have problems.

OK, you’re thinking to yourself that you don’t have the symptoms of a pickup problem, but you’ll now be able to
recognize it if it happens and know how to fix it when it does. John Himes would probably suggest you think again. If
the sump pickup can get plugged badly enough to shut down the engine, what happens when it’s plugged a little less
than that? Let’s say it’s just a little bit plugged, not enough to affect engine operation at 60 MPH but enough to start
limiting fuel flow at full power. Just as you’re really getting into the interesting areas of the speedometer, the pressure
in the fuel rail starts to drop off. The engine starts to run lean just when it can do the most harm; lean mixtures at full
power are a recipe for disaster. And you’re into the open-loop range of operation, so the oxygen sensors are not able to
correct the lean mixtures. Himes was cruising along at 140 MPH, and the next thing you know he was facing several
months of down time and several thousand dollars in mechanic’s bills to fix a couple of burned pistons. Now, lemme
ask again: are you sure your fuel pickup is in good shape? In fact, everyone with the earlier style pickup screen should
definitely upgrade; go ahead and order the part now.

Kevin Darling claims that his car starts more easily since he cleaned up his pickup, and has a lower, more stable idle.
Neither of those effects can be easily explained, but improvements are always welcome.

There is, of course, another way of dealing with the problem: discard the OEM screen altogether and install an inline
screen in the hose between the surge tank and the pump. This would have the advantage that, once this screen had
collected a lot of crud, you could clean or replace it and get the crud out of the system once and for all. With the OEM
setup, you’re probably leaving a lot of crud inside the surge tank even when you clean it as best you can. Also, with an
inline screen you may be able to pinch the lines and service it without having to drain the surge tank. Finally, if you get
a screen assembly with a clear housing, you’ll be able to see if it’s dirty.

The line between the pickup and the fuel pump is 1/2”, and finding a fuel filter or screen assembly with 1/2” fittings
may be difficult -- and you certainly don’t want to step down to smaller fittings, since the entire objective is to minimize
restriction in this suction line! Keep looking; Chad Bolles says NAPA carries fuel filters with 1/2” barbs. This author
found a suitable unit a local parts store; it’s a Wix filter, number 33299. Less than ten bucks. It has an all-metal
housing. It’s a pretty compact unit, helping ease installation a bit.

There are also various types of high-performance or specialty filters that might be used. Holley makes a unit called a
Volumax that includes a cleanable 60 micron screen element. It comes with either 8AN or 3/8” hose barb fittings that
screw into the housing, but 8AN is 1/2” so you might be able to find 1/2” hose barb fittings to screw into the housing.

Heavy equipment places that work on trucks and bulldozers may have suitable filter assemblies that can be fitted with
cleanable screens, but they are usually big industrial contraptions and will be difficult to locate in the XJ-S. They also
have threaded connections, so you’ll have to install some suitable fittings for connecting the hoses up.

Another possibility, of course, would be to tee together two or more 3/8” filters. Finding suitable 1/2”-to-3/8” tees may
be harder than finding 1/2” filters, but once you’ve put it together it’d be easier finding replacement filters.

You’ll need some 1/2” fuel hose -- another challenge. EFI hose is not necessary, this is a low-pressure application. But
finding any fuel hose in 1/2” size may require visiting an industrial hose shop rather than an auto parts store. See page
238.

You also need to get some clamps; EFI style clamps would be great, but 1/2” hose is big enough that regular worm
screw clamps work just fine.

The OEM fuel hose goes from the pickup tube to the pump inlet, only about four inches with a 90° bend -- too close to
put this filter in between. Instead, use a new piece of 1/2” hose to make a big circle from the pickup tube barb CCW
past the pump inlet, down, back to the right, up, and back left into the fuel pump inlet. Then install your filter anywhere
in this loop that’s convenient. Probably three feet of 1/2” hose total, but absolutely no sharp bends.