I know this has been discussed in the middle of several other threads but her's a piece of evidence from a drive I took yesterday. I filled my car with gas that purports to contain 1O% ethanol. I made certain it was really full. I did some local driving getting a miserable 10-11 mpg and racked up 24 miles. My gauge then read 3/4. Next I took a longer drive that was mostly highway and tried to be careful about going easy with the gas.

At the end of my 99.7 mile trip the gauge read damn near 1/2. I filled the tank and it took 5.94 gallons. So that's 16.78 mpg. The computer said 17 and adjusted the next time I started the car to 16.8 mpg. That's fine.

But the gauge seems to drop to the 3/4 and 1/2 indicators way too soon. I don't think 5.94 gallons represents 1/2 a tank maybe 1/3 or even 3/8?

The 1/4 tank reading having gone 24 miles at 11 mpg is also wrong.

Does this seem normal for these cars?

 

It doesn't sound right but I'm sorry that I keep forgetting to watch the gauge!!

I think 6 US gals is about 21.5 litres and the tank is something like 69l. I've managed to get 58l in and at the time Range was saying 15 (miles). That would be about 5l. There should also have been the 2 (Imperial) gal reserve, which would be a bit over another 9l. The numbers don't quite add up but are close.

hmm, l=litre, 1=one. In some fonts l=1 grr.

 

I do a lot of rural driving and I have been averaging 22mpg, but I have also noticed that the gas gauge drops very quickly from F to 1/2.

 

Bob we've discussed this before. There's a huge thread on this I think it was by a guy in Canada you might want to read where the guy ran out of gas with an indicated 1/4 tank left. I did a whole pile of math, and we got into engineering test mode to read the fuel senders individually etc.

My car does the same thing of eating through the first 1/4 tank.

Sometimes I wont even get all the way to full, even though the gas pump shut off. I've never had another car do that.

Ironically, as you calculated, the trip computer seems to be pretty spon on with the mileage calculations.

The S-Type holds 18.6 gallons of fuel officially. BUT I think only 15 of it is reported to the dash. There is a 1.5 gallon "reserve", and another gallon and a half or so they hide to make sure to keep enough fuel to not overheat the fuel pumps.

That explains premature running out of range / fuel level, but not Emptying too quickly in the begining. I don't thing the resolution of the fuel sending units is that great, especially at the extremes. OR the gauge algortyhm is too conservative (where a GM car stays past full for the first 50 or so miles), and tends to greatly overestimate the first 1/2 of a tank, yet empty quickly after that. I think these cars understimate the first 1/2 and drag out the 2nd 1/2.

Ironically my car had about 3/8 of a tank this morning. Indicated range was 104 miles. I left the house and headed out on my 35 mile commute. As I drove I left the display on range, just out of curiosity. Instead of decreasing, it actually increased. (Less traffic in the AM than PM). I got to work the needle hadn't moved, and I had 147 miles of range left...

Go figure.

Take care,

George

 

Whats weird is that mine, when the low fuel light comes on, I can only put in 13 Gallons of fuel.

 

That's about right.

18.6 total
-1.6 for fuel pump cooling.
-1.5 hidden reserve
= 15

Low fuel warning = 40 miles to go. so about 2 gallons left (of the reported 15) = 13 you take on.

Take care,

George

 

I thought we had larger tanks then that.

18.6 Gallons.

 

http://www.new-cars.com/2003/jaguar/...ype-specs.html

Edmunds Claims 18.4 gallons, Jaguar claims 18.6. Six of one, half a dozen of another.

Take Care,

George

 

I'm not trying to re-start that thread I just wanted to get people's experiences with the gauge reporting and it seems George's does the same stupid stuff. This isn't small potatoes because with everything that's going on in this fuel system the GD reporting system is a mess. On my car it does seem to be calculating the mileage on this last run properly. It didn't on the drive home from Atlanta when I picked up the car.

Can't fix it all but is there a TSB on that supposed first 1/2 tank not being reported properly?

 

Something I noticed on my 03 STR is that no matter what I can not get the fuel gauge all the way to the F, stops between 3/4 and F so I guess 7/8 full. I can run it to the red on the gauge and it will only take around 13 gallons give or take a bit so it falls in line with Mafioso's post above.

Is there a TSB or recall geared towards not reading Full on the gauge?

I'm getting good mileage by hand figuring:

65-75: 24-25 MPG
70-80: 23-24 MPG
80-90: 22.5-23.5 MPG

This was recorded during my 1800 mile trip from PA to Texas.. by hand. The computer was always pretty close.

Oh.. and my manual says:

Indicated refill capacity – E to F on fuel gauge . . . . . . . 16.9
Unindicated (reserve) capacity . . . . . . . . . . . . . . . . . . 1.5
Total refill capacity (advertised capacity) . . . . . . . . . . .18.4

 

Sounds like TSB S310-02 (fuel tank sender) VIN M45255-N11798

In the forum TSBs?

Doesn't sound quite like S310-04

 

It's similar but not identical to what mine is doing.
I'm going in next Tuesday for several warranty items, been waiting for the parts. One of them is a pair of new gas tank senders. We shall see ...

According to the service manager on the 2005 STR replacing them isn't such a big deal.

Bob S.

P.S. Coolant tank to be replaced and steering column squeak to be fixed and any software updates as well. Only 3 months of warranty left ...
My how time flys when you're driving too fast ...

 

Question. I used to run a Buell dealership. Some TSB's from Harley/Buell were treated as extended warranty items, anotherwords, if the problem occurred then it was replaced for free. Some were simply TSB's that provided information regarding a problem and that's all.

How does Jaguar handled their TSB's?

 

My VIN is M53209 so it falls in that range.

Reading the TSB , that is the issue, I see where it shows Labor Time Allowance of 1.3 hours and a Fuel Pump Module and Transfer Pump are listed by PN. My question is, does Jaguar cover these costs under the TSB? Sounds that way if they are 'allowing' x amount of labor time.

The TSB reads:
Mine doesn't bounce around, it just never reads full no matter how much fuel you add, 7/8 full is it.

Still think that applies?