Picture of when Fuel Gauge light comes on

[forrestjordan]

 I was getting low on fuel this morning, as I went for a drive down the beach highway.  I thought I would see how low the gauge would go before the light went on.  The attached picture shows that result.  The light went on just as the gauge hit the top left side of the "R".  It came on and I stopped right away to take the picture.  It was within a 1/2 mile of the next gas station and when I filled up the tank, it took a total of 16.958 gallons, US.  Is that a normal amount? Or is there such a thing as "normal" with these old gauges?  My car is a '70 280.
  (It is the first time I have driven the car that low on fuel, mostly because I am afraid of what might be floating around in the bottom of the tank. )
Forrest

[Peter van Es]

I regularly run my car as low as that, to when the reserve light comes on. When the reserve light does come on, some people have reported very little range left, so get to a gas station quick. You added 64.2 liters. I've been keeping track of my petrol filling for years now, and the most I've ever added is 74 liters (if I run it really low, I typically need to add around 70 liters). 74 liters is 19.55 US Gallons.

Note that it is quite difficult to fill up your tank completely, consistently. The nozzle will switch off well before your tank is full because of petrol surging up into the filler pipe. You'll need to rotate the nozzle into the filler pipe and slowly fill up the last gallon or so.

Peter

[bpossel]

I believe the reserve is 1.8 gallons on the 21 gal tank.
Bob

[forrestjordan]

Bob, when you say reserve, I take it you mean after the light comes on, the 1.5 is supposed to be left in the tank?
Peter, trying to keep the pump turned on is a major problem sometimes and that is prob'ly why it only took the 16.9 if it should have had 1.5 gallons left in the 21 tank.
I have started keeping a little notebook in the glovebox to record the miles and gallons now.  Now that I have run it low on fuel, I will keep doing it more often.

[Cees Klumper]

There are two sizes of tanks (as far as I know) and, although my car should have the 21 gallon one (80 liters) I've never been able to put in more than 64 or 65 liters, even when the level was really low - so I think I have a smaller tank in the car. I once ran it as low as to have the light come on, and the car started to sputter only a couple of miles later, as I was coasting into a gas station (phew!). I started carrying a reserve tank in the trunk, but safety concerns etc led me to just fill it up more timely. Like today, when I stopped because I was concerned it might be getting too low, and 'only' being able to put in 57 liters. That will carry me about 410 km's on mostly highway driving.

[Peter van Es]

The fun part of keeping track of your petrol filling, is that you can keep track of your mileage too. Now I've had lots of speedo problems in the past (now resolved due to having both a repaired speedo and very accurate rally instruments) but I know my mileage pretty well. Since the last set of changes on my car (123 ignition and rebuilt FI pump) I recently got 8 km/l... on a long motorway drive. Note that to measure your consumption accurately you will need to be consistent in filling up your tank also.

I've had my fuel consumption a lot worse in the past, am currently averaging about what Cees gets (7 km's per liter), but used to be a lot worse at 5 km's / liter. And here in the Netherlands, with gas at € 1,45 a litre, filling up a Pagoda costs almost €90-€100, or $128 - $143... every 450 km's or 280 Miles... How's that for Sticker Shock?

Peter

[forrestjordan]

Peter
i don't know the conversion but I try to only buy BP hightest gas.  The fillup I spoke about for the 16.95 gallons cost $2.949 per gallon for a total of $50.01.  Here in Florida, it is very flat no hills etc. so I might get a little better miles per gallon.  I will be keeping track from now on.
Forrest

[lurtch]

Hello All - - Since many of us have a 230SL, which has a smaller tank, I will go on record with this data:

I ran a check of these numbers just last week.

The 230SL tank  capacity is  65 liters  (or  17.2  gal).   While driving, my reserve light came ON and I refueled almost immediately pumping in 14.2 gallons.
 
Therefore the reserve fuel amount seems to be 3 gallons. Correct calibration of the gauge is uncertain, but the sender was replaced three years ago.


Does it logically follow that a smaller tank would have a larger reserve?

Larry in CA


   

[Naj ✝︎]

There are two sizes of tanks (as far as I know) and, although my car should have the 21 gallon one (80 liters) I've never been able to put in more than 64 or 65 liters, even when the level was really low - so I think I have a smaller tank in the car.

Hello, Cees,

Have a look at the second fuel tank picture in the wiki under fuel tanks.
You can see the full trunk left end trunk panel from under the car if you have the smaller tank.
With being able to fill 65 litres, I wouldn't think so.

naj

[Cees Klumper]

Hello Naj - I believe you are right, that I have the larger tank. I would have to double-check to make sure.

Still, I have never been able to get more than about 65 liters in, and that was with the reserve light on. Maybe a previous owner put the loot from his last robbery in the tank for safekeeping, I will have to check this out sometime ... and maybe it's worth running the car completely empty one day (spare fuel in a separate canister or two in the trunk) so I can finally change that fuel filter AND verify once and for all how much gas this tank really takes!

With 80 liters, I would be able to go well over 500 km's instead of the usual 400-420 that I dare go.

[Naj ✝︎]

Yes, Cees,

I get about 550 km on a full tank on long trips.

You can drain the tank using the electric pump once you get low enough that you don't need big containers to store the fuel.

naj

[forrestjordan]

Killing time at a book store while my wife shopped in the mall , I checked in a "Haynes Repair Manual" and found the following:
Capacities:
Fuel tank *                               Imperial            U.S. Measure         Metric Measure
Except 250C and 280 Series     14.3 gallons       17.25  gallons            65.0 litres
250C and 280 Series               18.0 gallons        21.5   gallons            82.0 litres
*Certain models have a reserve of 2.64 Imp gal (3.1 US gal. 12.0 litres).
Does this info confirm your individual findings?  The manual had a copyright date in 1987.
Forrest

[bpossel]

fyi...  In the BBB (section 0-3/12) it states that the 280sl has a fuel/reserve of 82/7 liters.  This is 21.6/1.8 US gallons.  It is amazing how many different numbers are documented (ie BBB vs Haynes, etc...).

The best thing is to know your individual car and fill it up before the reserve light comes on.  I'm sure that with age, the float will vary and give different readings.  When I fill up immediately after the light comes on, it seems to only take about 17 gallons.  Should take ~19 or 20...?

Bob

[Peter van Es]

Maybe a previous owner put the loot from his last robbery in the tank for safekeeping, I will have to check this out sometime ...

With 80 liters, I would be able to go well over 500 km's instead of the usual 400-420 that I dare go.

Cees, what may have happened is that you have a dent somewhere in your gas tank reducing capacity. I remember that when my car was inspected for it's FIA papers the inspector made a comment saying that I had such a dent - but it wouldn't cost me more than one, perhaps two liters.

As for filling up, I usually do it at 450km as the non-linearity of the fuel gauge (the rather fast dropping at the end) typically scares me into getting fuel. With 70 liters being added I should have 9-10 liters left (with dent) which should give me additonal range of about 7 x 9 is 63 kms, i.e. into the 500 kms. If naj is getting 550 kms he certainly doesn't drive the way I do!

Peter

[Cees Klumper]

You can drain the tank using the electric pump once you get low enough that you don't need big containers to store the fuel.

naj

Thanks for that tip Naj - hadn't thought of that ....

[Naj ✝︎]

 If naj is getting 550 kms he certainly doesn't drive the way I do!

Peter

No, Peter,

I'm very gentle with my car 

We were running low on fuel in Sweden. Stopped at a shop to ask how far the next fuel station was.
Oh, just about three miles down the road, and you are going the right way. 
About twenty miles later we found the pumps!
I think in Sweden, 1 mile = 10 km.


naj

[J. Huber]

So I had an exciting bit of driving this evening (for me).... Ever since this post aired, I was curious how much fuel remained in my tank after the red light came on -- and was planning to report here. The last few days, the gauge was getting lower but still no red light (my daily drives are only maybe 10-15 miles R/T). Anyway, this evening as I "offered" to go get sandwiches for the kiddos, I was determined. I was out and about and the needle was pretty much pegged down -- still no light! I started thinking what if my light is inop all of a sudden? This could be ugly -- out of gas and a bunch of hungry children... After the sub shop, I kept driving in town and basically cruised around the area where we have a couple stations. I truly started to get panicky -- the needle was not budging at all... What I won't do for Pagoda Science! Then -- Finally! the light flickered and then lit up the place! I promptly filled up. It took 15.8 gallons to the brim so I had about 1 1/2 gallons left (glad the light came on or the kids would have starved!)

PS I put in 54 bucks which to me is a ridiculous amount but I suppose a bargain compared to you guys "over there"! The MPG was also sucky at 14.75. I used to get around 16 or so in town -- but have been in this range the last couple years. Not sure why but that's another thread!

[jeffc280sl]

I filled up my tank before leaving on a 320 mile (Google map mileage) trip to Durham, NC.  Soon after arriving my reserve light began to flicker.  This is the first time I have had the reserve light come on.   I filled my tank with 18.68 gallons of gas.  My tank is 21.66 gal (82 liters) according to the owners manual.  When the light started to flicker I had a little less than 2 gallons remaining.  I'm glad the light worked and now I know the exactly where I stand when the reserve light comes on.

Mileage of 17.15/gal suffered as a result of my fip tuning.  I averaged 65 miles per hour with 2 brief stops.  I have the 3.27 rear axle.

[Jordan]

Has anyone experienced running out of gas going up a steep hill when low on fuel?  I only bought my 230SL late last fall and never really had a chance to drive it before the snow set in.  Last week we had some beautiful weather, the roads were dry and clear, so I deceided to take the car out for a drive and get new tires installed (they were 21 years old) two towns over.  On my return home going up a steep hill the car started to stutter and finally died when I reached the peak.    It then occured to me that I had never seen the gas gauge needle move off just over half full except when I turned off the car.  I don't know why I thought of the gas gauge but I called the garage I usually visit and they sent someone over with some gas (its a small town but I've since signed up with CAA).  The car started up fine and I drove the rest of the way home.  I've had the car out since and put 40L of gas in it, gauge is still showing just over half full, but it seems no worse for the experience.

I had the fuel sender out of the car earlier in the winter and it was clean, no gunk at the base, so I reinstalled it.  I now need to clean it internally, need a new one or maybe the electrical is malfunctioning. Time to change the fuel filter as well.

Anyway, back to my initial question, with the gas tank being so flat, has anyone else experienced a problem going up a steep hill when they were low on fuel?   The hill I was going up was pretty long.

[jeffc280sl]

http://www.sl113.org/forums/index.php?topic=1712.0

Have a look at the gas tank tour.

[Garry]

Just as a comment, my petrol gauge reads lower going uphill and higher going downhill, can only assume the correct level is somewhere in the middle of the two readings!