My 77 XJ12 recently started to experience an apparent fuel starvation issue. Momentary loss of power at speed while climbing hill. I will start at the tank to try and remedy. I have read posts about changing or removing fuel tank pickup tube screens as they are likely plugged up by now.
My question is can this be done from/thru the tank drain plug?
If not how?
Tanks have been drained all filters and hoses changed etc.
Thanks Mark
The screens on the saloons are different than the screen on the XJ-S. On the XJ-S, the typical problem is that the surge tank will collect a bunch of loose particles. When running, these particles gradually accumulate on the screen and plug it up, and the engine falters (or burns a piston, if you’re pushing it hard). When you shut it off, the particles fall off the screen back to the bottom of the surge tank. Next time you start it runs fine for a while until the screen gets plugged up again. After draining the tank to R&R the pickup screen, it’s found to not be very dirty – and the problem remains after reassembly unless you found a way to clean out the surge tank itself.
Solution for the XJ-S: Remove the pickup screen altogether and throw it over the hedge. Install a 1/2" inline fuel filter in between the pickup tube and the pump inlet. That way, particles sucked into the pickup get caught in the fuel filter and stay in it when the engine is shut off. Remove the inline filter and replace with new, which gets the crud out of the system.
I believe so. On Series 1 cars at least, drain the tank by removing the inner threaded plug, then remove the outer threaded plug (has a gasket IIRC). The inlet screen has a nylon skeleton which is just a “push on” fit to the ~5/16 OD pickup pipe.
I agree with Kirbert’s suggestion; many have fitted an inline filter inside the boot, after removing this filter. Or, you can use both. There is info in the archives. IMHO.
Please don’t use both. You’ll defeat the intention of getting debris out of the tank (the OEM screen will keep it in) and the two filters in series add to the resistance to flow on the inlet side of the pump, increasing the likelihood of cavitation.
Thanks to you and Kirbert. I will drain fuel and take a look.
Definitely favor the over the hedge and new filter solution. However i seem to find that with most old Jag owners, myself included, over the hedge means into another box.
My wife thinks the three of us need to go to counseling. I asked if the third was her or my second jag??
Good point. Although large debris could conceivably clog the pickup tube were the relatively large surface area filter not attached, I suppose that’s unlikely. Just thinking, I bought two inline filters ~10 yrs ago but they are still not installed. I removed one tank filter so there’s nothing there until the fuel pump pickup. Other side still has the in-tank filter. Seems like I might procrastinate?
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I put a magnet in the surge tank.to catch rust particles.
But isn’t that rust is not magnetic?
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Did you try changing to the other tank, Mark…
With clogging filters it’s usually the tank in use that is affected - the other one temporarily free. And changing to the other tank accesses the free one - and the engine should instantly recover…
My point is that loss of power may have other causes - and it is wise to do simple checks before taken action…
That said; at cruising speed the engine uses 12 - 13 L/h, or some 2 L/min - so fuel flow is not high. The advantage of the in-tank filter is to keep large pieces out of the fuel system - to be drained from the tanks when required. Smaller particles passing through the in-tank filters are chewed up by the pump and caught in the main filter. Adding inline filters may catch smaller particles, but with adequate dimensions you can add as many filters as you like - they should not, while clean, impede fuel flow…
Clean tanks do not need filters - and Jaguars got by with in-tank filters, without extra filters, for years. Adding adding filters is not harmful - removing the tank filter may be…
Frank
xj6 85 Sov Europe (UK/NZ)
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Frank,
I did change tanks after the third time. These (3?) episodes each lasted about one second. Engine power returned to normal with no backfires or other unsettling events.
I know I could have other causes,Vapor lock?, clogged filters or ? Just thought I would start at the back and go forward for a change of pace. 
Her and the two Jags ???
Cyderman,
at the current costs of decent fuel pumps I’d protect them by additional simple filters between the tanks and and the pumps. On the suction side there isn’t much work for the pump as both tanks are basically above the pump level and inline filters don’t produce too much resistance.
Kirbert has a valid point though: the debris needs to go somewhere. Now there are transparent plastic filters that are supposed to be changed out when turning red/brown/black/anything but clear. There are also filters allowing to remove and clean the filter element. Checking and changing the works fuel filter at the front end of the spare wheel well will shed light on the situation inside the tanks. While it is a good idea to check all possible causes for your issues, any serious checking of the tanks will produce a serious mess:-(
Good luck
Jochen
75 XJ6L 4.2 auto (UK spec)
Good Point! I’m not the person with the problem. Right?
Anyone have a part# for a 1/2" inline fuel filter? Thanks!
NAPA 3299 or WIX 33299 will work. 1/2" nipples. Same filter, different box.
Cheers
DD
May I be so bold as to recommend using some Berryman’s B-60 “High Mileage” Fuel System Cleaner? This is for vehicles that haven’t had their fuel system/combustion chambers cleaned for more than 50,000 miles. It uses High Energy Solvent Technology (HEST) that outperforms every other fuel additive on today’s market. I have been using this for years and it works when nothing else will.
If you use Berryman’s B-12 “Chemtool” fuel additive in every fourth tankful of gasoline, regardless of fuel grade, you will see, feel, and notice improved mileage and reduced octane requirements. (This is because the intake deposits and carbon won’t have the opportunity to accrue over time).
Trust me, it works!
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This is what I have
Found them on e-bay, made in China but very good quality and no leaks.
I like them because they are thin and they don’t interfere with the spare wheel.
They suppose to be high flow, they have a hard filter element and you can take them appart to clean the filter very easily.
Had some clear glass ones before but they were cheap and flimsy…
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Certainly, Aristides - but the see-through allows some monitoring…?
Frank
xj6 5 Sov Europe (UK/NZ)
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Next time you have them apart, please take some pics and post them!
Indeed, but they were really not trustworthy.
I bet they are better ones out there though.