The V12 of a 89' XJ-S got caught on fire

V12-Engine
1

Hi guys,
an 89’ US version of a 5L V12 engine got caught on fire that was extinguished fairly quickly because it happened close to a movie making stage in downtown Budapest, but it seems like it wasn’t quick enough, the engine cable harness suffered major damage for start.

see some pictures here:
http://pumi.org/geza/temp/browseable/89-Jag-XJS-V12-USA/

They seem to be quite boring since everything is all white.

My friend tried to figure out what could have caused the fire and when he gave 12V to the fuel pump, he noticed that fuel was coming out from the vacuum controlled fuel pressure regulator, so it looks and “smells” like that this puppy was the guilty one.

For start, what do you guys suggest, how should we clean the extinguisher dust off the engine with the least amount damage? What I mean is, how sensitive a V12 engine to steam cleaner:? Because that’s what we would use as a first idea but I was thinking maybe we would just add more problems to the unknown existing ones since the steam vapor could get into any harness and just give more puzzles for us that to be honest, we don’t need right now.

And for the 2nd step, we’d like to replace the engine harness but we’re not familiar with this engine on this level, the question is: how many harnesses are we talking about here? One huge octopus, or each side has it’s own? Where is or are the junction connectors, in the engine compartment or somewhere under the dashboard?

And generally speaking, what do you guys suggest how should we proceed to fix this engine the most efficient way timewise?

We already know that we will have purchase the engine harness(es), fuel pressure regulator, and most likely the ignition modul, that sits on the top of the engine (what a weird place to put that by engineers!) since it must have gotten a lot of heat. And whatever we find damaged after the clean up, then we will have to order the parts from somewhere, install them and try to start the engine and then go from there, order the second batch of parts. This is my idea of a possible work flow plan, but I could be wrong.

Geza

2

an 89’ US version of a 5L V12 engine got caught on fire that was
extinguished fairly quickly…

see some pictures here:
http://pumi.org/geza/temp/browseable/89-Jag-XJS-V12-USA/

Someone has added a fuel filter between the RH FPR and the rail. That was
a poor decision because the filter itself is anchored to the fender well while
the FPR and rail are on the engine and therefore bounce around as the
engine moves on its rubber mounts. That probably stressed those hoses
greatly, and they are under pressure. I’d recommend removing that filter. If
it is decided that a fuel filter within the engine compartment is called for, one
should be located BEFORE the RH FPR, where the fuel supply line first
enters the engine compartment.

…when
he gave 12V to the fuel pump, he noticed that fuel was coming out from
the vacuum controlled fuel pressure regulator, so it looks and
“smells” like that this puppy was the guilty one.

Obviously that FPR – whichever one it was – needs to be replaced. After a
new one is installed, though, repeat that test. There is SOME possibility that
the FPR was damaged by the fire and the primary failure is a leak
somewhere else in that system. The injectors, for example, are another
common fuel leak source, as are the short hoses connecting them to the rail.

For start, what do you guys suggest, how should we clean the
extinguisher dust off the engine with the least amount damage?

I can’t help you there. Will the stuff just wash off with a garden hose?

And for the 2nd step, we’d like to replace the engine harness but
we’re not familiar with this engine on this level, the question is:
how many harnesses are we talking about here?

You’re talking about at least two harnesses: The engine harness and the
injector harness. There’s a page on fabbing an injector harness here:

http://www.jag-lovers.org/xj-s/book/InjHarnessRebuilding.html

Also beware of the silly little coax wire from the ign amp across the rear end
of the engine to the engine harness on the right side. It is often baked and
cracked and shorting out on cars that HAVEN’T had a fire.

…and most likely the ignition modul, that sits
on the top of the engine (what a weird place to put that by
engineers!)

Perfectly sensible place, actually. It uses the intake manifold as a big
aluminum heat sink, cooled by the cool air flowing through it. They’ve had
far fewer problems with cooked ign amps than the earlier Opus cars did with
their finned amps down in the vee.

Note that you can replace the innards of that amp far cheaper than buying a
new amp. At least here in the US, I dunno how much a GM HEI unit costs
where you are.

You’ll probably want to rip that hood liner out. Some of us have replaced that
ugly thing with a thinner, aluminum-faced material cut to size and taped in
place using aluminum tape. You need to make very sure that thing cannot
droop down and foul the throttle linkage.

– Kirbert

3

For the ABC powder:

Vacuum/brush.
Blow off with compressed air.
Spray with water, then a mild spirit of vinegar solution (The powder is basic).
Rinse with water.
Blow off with compressed air.

Now go back and hit any areas with powder residue (it sticks to hot surfaces). Soap and scrub, vinegar sol’n.

Now spray the whole thing with a baking soda sol’n.
Rinse again with water and blow off with compressed air.

Now hit all the connectors, opening them one by one and rinsing with Alcohol, then blowing dry and finishing off with contact spray.

Getting all the powder out is a PITA.

1 Like
4

Kirbert and Andrew,

Thank You for giving me so much info and pointers within such a short time, now we have enough info to begin the journey to the unknown. :slightly_smiling_face:

We still have to figure out where to get the parts from, so just to get some ideas of how much money we’re talking about, could you send me the URL links of Jag parts store where you guys prefer to buy parts from either in the US. or the U.K.?

I read the excellent post on how to rebuild or remake injector harness, based on that info, it doesn’t even make sense to buy original harness, instead either we should build or buy a teflon coated one.

Andrew: could you give me more info on what ratio do you recommend mixing the vinegar or baking soda with water?
(The common vinegar that is available here is 20% strong.)

Geza

5

I get “Spirit of Vinegar” and dilute that to about 20%. Spirit of Vinegar is refined to remove the sugars/flavours, so it’s just acietic acid. It will attack Zinc, but it takes a while at such concentrations, so just use a spray bottle, leave it to work for about 10-15 min, then rinse.

One the Baking Soda, I use a cup or two in a bucket of warm water. Again, just spray on liberally, wait a bit, then rinse.

Follow with a pure soap wash and rinse. I then use Alcohol… but I’m a bit OTT with some things.

1 Like
6

Andrew: Thanks for the clarification.

Geza