XJS Fuel injectors

Hi everyone, i hope someone can help, ove seen some amazing responses on here.

My 85 V12 HE (which I’ve had for almost half her life). was running (lumpily) this week after sitting for three years at a paint shop, it then got lumpier and stopped and now won’t even cough. I have a good spark from the one plug I can get at, I’ve fuel after the pressure regulator, i can hear the injectors ticking on turn-over but there is no fuel coming out of the injector (I’ve removed one from nearest the radiator), I can get a spray of fuel if I poke the valve(?) up from bottom of the injector…

I have 12v (to ground) at both pins of the injector plug, I think I see a drop in voltage when I turn the engine over.

I have continuity through the infamous white wire and 35megaohms between the conductor and the shield

Could it be crap in the injectors?
How can i bench test an injector?

Do you have any suggestions as to what I can check next?

Thanks in advance.

As described, it does sound like clogged injectors. Paint dust and filler get everywhere in a bodyshop.

To bench test an injector, hook up a compressed air hose at 2-3bar on the inlet and connect up the injector to a spare 12v battery by tapping one wire to the battery to complete the electrical circuit. That should make the injector click and spray air when it does so.

To clean an injector, get some paintbrush cleaner, typically a blue liquid, and soak the injector in it. If you can do that whilst it is in an ultrasonic bath, then all the better.

Repeat the test, you should have a nice spray pattern.

You can even put some paintbrush cleaner in the hose and attempt to spray that. Take care with anything flammable and be mindful of how much stored energy a car battery contains.

kind regards

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Wonderful, thanks Marek, I’ll let you know how i get on.

Sitting three years with ethanol gas is not good, your fuel system could easily be clogged, and that gas is now bad. Ethanol attracts water too, especially if tank was not full, so you could have water in the gas.

Did you put a fuel additive like StaBil in before it sat for three years to preserve the gas? Or did it have non ethanol gas?

I’d echo that. The fuel may have started degrading and that will mean gel and sludge separate out of solution. If that is the case, you may need to drain the tank and the swirl pot in the boot. This can also kill your petrol pump.

It should be quite easy to look into the swirl pot using a torch.

kind regards

Don’t know where OP is located but Torch in Marekh’s country means flashlight here in the states.
Might not like the result if a Torch as in open flame gets close to the tank old gas or not.

Might want to say flashlight :slight_smile: I always have to think twice when I see the word torch, since being on these forums

To many folks, who are not used to torch as something other than a “fire on a stick”, it could be catastrophic.

But I am sure the vast majority of do it yourselfers would know better than to use fire to illuminate a gas tank :slight_smile:

Fair point. We haven’t used the word “torch” to mean “fire on a stick” since Roman times. Even the Romans got wise by the time the Facelift VI litre XJS was introduced…

Let’s use one that runs on batteries.

kind regards


Aye!!! That thought hit me as well. As a former Claim erson, i am very sensitive to fire!!1

Candles sare forbidden in tis house!!

I only intended the car to be at the paint shop for two weeks… Covid lockdown intervened and hey presto… so the car’s general condition has deteriorated markedly, obvs there was no thought of putting a treatment in the tank as it was only going to be two weeks…
Hopefully a good clean will get her running again. She’s been a dajlybdriver for the best part ot 20 years (untill the paint shop…).

Unfortunate. Draining tank, new fuel filter, and refilling and you may get lucky.

Worst case scenario, you may have to get injectors professionally cleaned because they’re gummed up, and bottom of tank could be rusting now - That water will have separated from fuel and sat at bottom of a steel tank for a good couple years.

When i bought my xjs, it had sat for 7 years. I had injectors cleaned, ended up not being that bad, about 95%. But bottom of my tank was totally rusted, with pinholes starting. Replaced it myself.

Was yours stored in a dry place? Other problem i had was electronics slightly corroded from cold/damp so long.

So far the tank seems fine, I’ll get it emptied and cleaned, the injectors will probably need to go away, that’s a pain but if it works it’s worth it.
Thanks for the response :slight_smile:

If the injectors are indeed bad, contact Mr. Faircloth (jaguarfuelinjectorservice.com). No affiliation…

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Thanks, ive now got the fuel rail off and on my bench, all injectors are firing and the all seem clear, seeing a jet of fuel when i trigger the injector. (got a bug sprayer pushing air into the fuel line).
So next…?
Any idea what i should see on the electrical connectors? I’m seeing 12v on both pins (to ground), 0v across the pins.

Thankfully if not gummed up, I’d guess water in fuel and/or bad gas?
Drain tank, rinse with gallon of gas, replace fuel filter, put in just a few gallons new gas, fire up?

I agree with that recommendation. I have used him and am very satisfied with his services

Going back to your very first post. Sounds contradictory. You hear the injectors clicking, but no fuel coming out. Yet…fuel comes out if you depress the injector pintle. If you depress the pintle and fuel comes out, then you have fuel to the rail and fuel thru at least one injector…the one tested. Albeit, a pressure test may be in order down the road. Maybe the clicking is not the injectors, rather some other engine noise. Your last post…you have 12 vts at each injector harness connector…as there should be. Agree with Gregs’ comment…add some good fuel and see if it fires up, and, if so, how it runs. SD Faircloth

It’s always contradictory… classics, who’d have em.
Yes, i seem to have everything, I’ll connect up the injectors and see what i get.
I’ve had my big screwdriver on the injectors whilst cranking and the clicks are from the injectors. I’ll have to go backwards beforeni go forwards.

I think I would check if there is water in the fuel/tank. You can disconnect the fuel line under the hood at the connection to A bank FPR, and put the hose in a can…a deep can so gas doesn’t blow everywhere. Let the pump run…maybe 10 seconds, and stop . Pour the contents into a glass container so you can see if any water settles to the bottom. SD Faircloth

Yes, i have the hoses all disconnected so blasting some fuel through will be a great idea, i already smell like i shower in gasoline. :grinning: