On some of my other vehicles I have a tendency to fill the fuel tank with as much fuel as possible. I mean that there is fuel all the way up the filler neck. I also know some cars have a fuel vapor recovery system which has a vent hose near the top of the filler neck. Do I assume Jaguar has the same set up and if so how far down is the vent. This would give me an indication where I need to stop the fill. With a lot of the oxygenated gas the foam usually triggers the hose off so I need to wait and fill until I get my desired level. What are others doing.

 

My XK rarley take an extra .5 gallon after intial fuel shutoff if that helps. That is about 3-4 more nozzle triggers.

 

I stop adding fuel/gasoline once the pump shuts off automatically.

Otherwise it is likely that the gas can overfill trying to get 1/10th of gallon extra. Then you have gas running down the side of the car on the paint.

There are many articles written why you should NOT overfill the gas tank.

HowStuffWorks "Avoid Topping Your Gas Off"

 

You will ruin your charcoal canister that way and trigger a CEL! I'm surprised it hasn't happened already!

Why are you doing this? Do you have OCD?

 

Nothing to do with OCD just getting more miles. While pumping you don't see the foaming of the gas . This triggers the nozzle to shut off. If you were to look into the fill neck the fuel recedes below it. The trick is to find the sweet spot and do a slow fill to that level. In my Lexus that is about 2 1/2 gallons which is safe and below the vapor recovery vent. Range on the Lexus V6 is about 480 miles at highway speeds. It will be interesting to see how far the Jag will go. I'll be taking a road trip next month and we'll find out.

 

Once I get my first click, I will give it one more. I've already had the treaded overflow onto the paint once. It won't happen again!

 

I guess my bladder usually goes before the fuel tank does!!!

It just surprises me how apparently there are people who top off their gas, despite all the warnings on the fuel pumps and in (probably) vehicle owners manuals forbidding this practice. I already had an XJ6 with a clogged vapor recovery system that ended up creating a negative pressure in the fuel tank(s). Allowed to continue, the fuel tanks could've imploded!

https://www.jaguarforums.com/forum/x...mplode-112224/

 

I don't.. i tell the guy at the station: Full Special.. and he does the rest..

 

Rich the one thing in the article that would be a problem with the car is liquid fuel getting into the engine vapor system. I want to avoid this so that is why I was looking for the fill distance. Our gas pumps don't have a vapor recovery type hose so it just goes to atmosphere here. As to gas on the paint unless you do it all of the time it just washes off with no problems. The other post of the imploding tank is relevant if you end up filling the vent system so that is avoided. The auto shut off on the gas pumps trigger when hit by fuel. As I mentioned when fuel is aerated it foams and shuts off the pump prematurely. You can see that when you fill a gas can so after you let it settle you can get more fuel in without overfilling the system.

 

Correct me if I'm wrong, but foam is comprised of liquid. Ever wash your car and get foam bubbles on the ground. Once they pop, isn't the ground wet?

Plus a lot of times, fuel in the ground is colder than ambient air. If you fill up and park your car for a few hours, fuel can expand and then you will most certainly have a problem.

 

Yes , true and when the foam subsides you have less volume of liquid. Yes , true if you fill up and don't drive far and let it sit in the sun the fuel will expand. That's something you shouldn't do. I usually will top off only when I will be taking a long drive so there is not an issue of expansion. I am trying to see what the range of this car is as it is new to me. I will have a small trip next month to visit friends . It is around 230 miles and will take almost 4 hours and it will be on 70-80mph highways. I assume this would be a non-stop journey but just wanted to get a little insight into it. I don't know if I will get 20 or 22 or 24 MPG so everything is speculation at this point And I will top off before hitting the road.

 

I just finished parking the car on the lift today and had another chance to look under it. I see Jag continues with their twin gas tanks but I couldn't see the crossover pipe. I followed the inlet pipe up to the gas cap. Up near the top of the filler neck just behind the gas cap there is a small can located down about 6"-8" below the fill cap. This looks like a small liquid/vapor separator. So the net for me is I can fill the tank about 8" below the cap. Next to the vapor can just above it is the tubing that goes into it and then there is a piece of overflow tubing that runs along the lower fender panel. Just a little info in case anyone wanted to know.

 

If you mean two separate tanks, it is actually a saddle tank but would look like two from under the car.

 

Yep thats it but you can't see it with the shielding in place. Thanks.

 

No trouble - I did a 260 mile trip recently (east London to Fishguard, Wales), cruising 80-85 most of the way, and still had 30 miles showing on my range when I arrived. And I wasn't being deliberately gentle, because I'd assumed I'd have to stop for gas - the range showing when I started was 230, but I guess that was based on my normal city driving. I've since noticed that, after a long motorway drive, a fill-up reports 305 miles range.

 

hehe... me too. Besides I let to get in frequently to give the car a once over/quick glance.

 

As i looked at the tank and based on the earlier post I see it is a saddle tank I have a new question. The inlet from the fuel fill is about 3-4" up from the bottom of the right side tank. I also don't see a cross over pipe and the fuel pump is in the left side saddle tank. I wonder what the inside looks like because I can't see how the fuel gets from one side of the tanks to the other. Just curious not ****.

 

All the plumbing is internal. These pictures should help.

To answer the original question, I always fill my tank until the pump cuts off then carry on to the next complete litre. Not sure why really, maybe it is my OCD, but I have never had an issue doing that (other than wet shoes once!).

 

Excellent , so I see there are 2 jet pumps and 2 floats . Interesting method to transfer fuel to each tank. Live and learn and I bet this is expensive. Thanks.

 

I guess it means no fuel starvation under heavy cornering. And having two floats means more accurate fuel level reading (the auxiliary junction box averages the two readings).