Escadrille Ecosse Posted May 1, 2024 Posted May 1, 2024 47 minutes ago, PaulAA said: Loins girded, we had an outing in the XJ over the weekend. Lovely weather and we went to visit the in-laws. A round trip of 160km, starting and finishing in the city, but mostly on the equivalent of A-roads, cruising at about 80kph. Gentle stuff, no severe gradients, no 'launch control' starts I brimmed the (left) tank before the trip and have just re-brimmed it after. And then fell over. 19litres/100km = 12.5mpg. I wondered if there is a hole in the tank, which odourlessly eviscerates the contents. Or a wily neighbour with a pass key to the filler lock and a long piece of flexible tube. I even wondered whether I'd re-filled the wrong tank in a moment of delirium. But no. It really is that thirsty. Thank goodness I didn't buy a V12. Somewhat 'challenging' fuel consumption for steady out of town stuff admittedly. Gulp! Handbrake on? Braking parachute deployed? Dead knight in full armour and his equally dead horse in the boot? Regardless, congratulations on an otherwise successful outing.
Nick Jones Posted May 1, 2024 Posted May 1, 2024 3 hours ago, Escadrille Ecosse said: Somewhat 'challenging' fuel consumption for steady out of town stuff admittedly. Gulp! Gulp indeed…. That is pretty fierce. Don’t think the Vitesse is that bad on the track……. Filled up and put 33.2 l in this evening after 196 miles, about 86 of which were on the track largely at full chat…. Plus some very crappy traffic on the way back ….26.8mpg. I had to go out and retrieve the receipt to check! The Jag would be an ENTIRELY different user experience though…… As Colin says, congratulations on the successful voyage. Probably best not let management know the bunkering costs though
rogerguzzi Posted May 1, 2024 Posted May 1, 2024 Hello All I know Spitty is not in the same leage but I will stick with my 45mpg over the whole year 5,800miles Roger
Escadrille Ecosse Posted May 13, 2024 Posted May 13, 2024 For those of a sensitive disposition look away now... 2
PaulAA Posted May 15, 2024 Author Posted May 15, 2024 DIY airbag installation, anybody? On 5/13/2024 at 6:19 PM, Nick Jones said: 6mpg with that load I think it's a 2.8, so nearer 8mpg 1
JohnD Posted May 16, 2024 Posted May 16, 2024 You're installing new airbags, Paul? EXTREME care! I used to attend a training course for rally rescue crews. We used hydraulic cutters etc to take cars apart and extract 'willing' volunteer casualties. A star turn was a demonstration about removing a steering wheel from someone's chest by cutting the steering column (really!). That could trigger the airbag by shorting the wires, so an instructor would isolate them and fire it with a 9V battery. Bad enough in a crash, even if if it does save your life, but it could really spoil your day in the workshop! From YouTube, not my course!
PaulAA Posted May 17, 2024 Author Posted May 17, 2024 23 hours ago, JohnD said: You're installing new airbags, Paul? Heavens, no, John! That would be stratospherically above my pay grade! It was my clearly not very witty commentary on Colin's XJ6 picture. Plaid, linen and silk airbags.
PaulAA Posted March 10 Author Posted March 10 The Jag season has started and my wallet has reported me for assault. 180km round trip at: (small trumpet fanfare) 10mpg. There are no words.... 2
PaulAA Posted March 11 Author Posted March 11 10 hours ago, PaulAA said: There are no words.... ... although my wife found a few. Some of them were quite choice as well. 3
Nick Jones Posted March 12 Posted March 12 On 3/11/2025 at 5:23 AM, PaulAA said: 10mpg. There are no words.... I think there must be something wrong with it. I mean…. They are bad….. but not that bad!
Nick Jones Posted March 12 Posted March 12 Yeah…. But the really crappy ones are probably V12s and the rest are at least 50% better, though using the AJ6 and on injection….. I dunno - I feel like mid teens should be possible. Still scary….
thebrookster Posted March 12 Posted March 12 4 hours ago, Nick Jones said: Yeah…. But the really crappy ones are probably V12s and the rest are at least 50% better, though using the AJ6 and on injection….. I dunno - I feel like mid teens should be possible. Still scary…. Hmmm. Maybe down to "driving style" possibly? Without wanting to judge, I was wondering if the "choice words" of the wife was down to the fuel consumption, or maybe how that figure was achieved? 🤪 🤔 2
PaulAA Posted March 12 Author Posted March 12 2 hours ago, thebrookster said: I was wondering if the "choice words" of the wife was down to the fuel consumption, or maybe how that figure was achieved? Harsh. Honest, guv - I drive like an aged don in the Jag... if there's anybody looking. This shocker emerged on Sunday evening. I'd managed to get both tanks to almost empty over the winter, and I'd brimmed just the left tank the previous evening and seen the needle sit plumly over the '4/4' mark. But on Sunday morning it was below the '3/4' mark ('ah, ze first clue, Monsieur'). Squeezy float? Tired sender unit? 185km later, having intentionally run it off the left tank only, with the express intention of vainly seeking reassurance that it doesn't consume that much, the tank was empty. 44 litres empty. Hence the desultory post above - 10mpg. Just to fill in the detail: tyres properly inflated, handbrake not applied, parachute not deployed, HD6s balanced and mixture adjusted with the Gunsen last summer, plugs looking only slightly blacker than they should. Most importantly, no leaking pipes either from gravity or under pressure. Seemed unlikely that that amount of fuel was being burnt wastefully... But yesterday evening, I wandered down to the garage and idly flicked over the tank switch to the right tank and the gauge showed it to be nearly half full. Having been practically empty on Saturday evening. Which, roughly balancing the amount of fuel I'd bought and the amount I still had, would suggest a more respectable 18mpg, give or take. The pipework on the Series 1 is pretty simple and doesn't include either a pressure relief return or a balancer between the two tanks, so the only possible explanation for this is that the (nearly new solid state SU) fuel pump on the right tank is allowing back feed. Having consulted the XJ community, this explanation turned out to be too simple - fuel cannot migrate between the tanks. Yeah, right.
PaulAA Posted March 12 Author Posted March 12 Two tanks, two pumps and a T-connector. Simple. Paul * Feel free to compliment the cleanliness of the underfloor area. 1
Escadrille Ecosse Posted March 12 Posted March 12 6 minutes ago, PaulAA said: Feel free to compliment the cleanliness of the underfloor area. What a lovely clean underfloor area 1 3
JohnD Posted March 12 Posted March 12 (edited) Paul, A few years ago(!) I asked for advice on how to plumb twin tanks (https://sideways-technologies.co.uk/forums/index.php?/topic/8972-theoretical-question-how-to-plumb-twin-fuel-tanks/#comment-122528) ) and received useful advice! In particular that some Jags had them. Recently, I bought a solenoid valve that such a Jag would have llke this. It's a simple, on-off valve. I don't see one in your pic. Just two fuel pumps and a T-piece. Does yours have the solenoid valve? I'd like to know where to fit it! John Edited March 13 by JohnD
Nick Jones Posted March 13 Posted March 13 2 hours ago, PaulAA said: Having consulted the XJ community, this explanation turned out to be too simple - fuel cannot migrate between the tanks. Yeah, right. And yet….. migrating it clearly is. Another collision of theory with reality Possibly mpg is indeed better than 10!
2.5piman Posted March 13 Posted March 13 Paul,. S.U. pumps have inbuilt check valves, that is the very likely reason for fuel ging to the right tank. It doesn't take much debris for the inoperative pump to allow fuel to pass. That is where I would look. Alec
JohnD Posted March 13 Posted March 13 Some rally cars have dual pumps fitted, for reliability through redundancy. But good practice is to fit non-return valves as well, else the running one can push fuel backwards through the non-running pump. John
PaulAA Posted March 13 Author Posted March 13 3 hours ago, 2.5piman said: Paul,. S.U. pumps have inbuilt check valves, that is the very likely reason for fuel ging to the right tank. It doesn't take much debris for the inoperative pump to allow fuel to pass. That is where I would look. Alec Thanks, Alec. That's what I've been looking for!
PaulAA Posted March 13 Author Posted March 13 11 hours ago, JohnD said: Paul, A few years ago(!) I asked fircadvicevon how to plumb twin tanks (https://sideways-technologies.co.uk/forums/index.php?/topic/8972-theoretical-question-how-to-plumb-twin-fuel-tanks/#comment-122528) ) ans received useful advice! In particular that some Jags had them. Recently, I bought a solenoid valve that such a Jag would have llke this. It's a simple, on-off valve. I don't see one in your pic. Just two fuel pumps and a T-piece. Does yours have the solenoid valve? I'd like to know how to fit it! John John The Series 1 cars (like mine) had a very simple set-up, relying on the inoperative pump to stop fuel being channelled to the unused tank, without additional valves. The pump itself determines the quantity/pressure of fuel being pushed through. The union of the two supplies is an open T-connector. Later cars had a single pump ahead of a change-over solenoid as per your image, which linked and regulated the feeds from the two tanks. Other than providing a return feed for excess fuel, the only effect of the change would appear to be to (i) save money on one fuel pump, and (ii) incorporate more opportunity for failure. Paul
PaulAA Posted March 13 Author Posted March 13 10 hours ago, Nick Jones said: Another collision of theory with reality It does appear that certain car marques attract wisdom of the unshakeable variety. 1
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