FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

GRIFFIN · 2019-04-05 02:15:12

I had a very close escape a couple of days ago. Wanting to run the fuel tank low to fill half with diesel and top up with some of Tesco's finest 70p a litre vegetable oil, I was waiting for my fuel low light to come on. I was about 5 or 6 miles from home at about half ten at night and the fuel gauge was just getting into the red when I could feel the occasional unevenness from the engine. At first I started to think that disabling my EGR valve hadn't solved my problem and that something serious was happening. However, because the fuel tank had never been so low since buying my scudo, I wondered if it was just low fuel, but my low fuel light wasn't on even though it lights up for a couple of seconds when the ignition comes on. Very puzzled I decided to drive to my local Tesco a couple of miles past where I live to try putting some fuel in, just on the bypass a mile away from Tesco the misfire grew worse until the engine eventually cut out. Bugger, I pulled into an industrial road and after trying to prime the fuel system, to no avail, I managed to turn the van round using the starter motor and eventually the engine spluttered into life so I headed a few hundred yards to a local fuel station where it cut out again. I half filled the tank, primed the pump and it roared into life, yikes wow that was close.

So my question is, why did the fuel light not come on and why did it run out of fuel when the gauge indicated just under a quarter tank or so?

My Scudo has a disabled access ramp built in and air suspension to lower the back end. I would assume that during the adaptation, a different, non original fuel tank was used to make room for the lowered floor in the back and I wonder if they have perhaps used the original fuel sender/fuel take off unit which either doesn't indicate the correct level or takes the fuel from higher up than it should in the new tank?

Has anyone had a similar experience or indeed any experience of fuel tank changes causing problems in a disabled access van? I'd like to try and solve the problem if I can but short term I'll just keep the fuel level high. I consider myself lucky this didn't happen at 2 a.m. somewhere out in the wilds big_smile

Cheers, Griff.

kenbw2 · 2019-04-06 22:07:22

My 2000 van runs out one notch under a quarter! The 1999 one changes its mind each time

I've often wondered if it's the sender or the dash. I have a spare dash actually, I'll give that a try

cliffo · 2019-04-07 08:08:26

My 1998 ran out just under the quarter mark - I've never seen the fuel light!

kenbw2 · 2019-04-07 09:45:29

I always make sure I have a 2 litre bottle of veg oil in the van for this reason, enough to get me to a petrol station. Or a 5 litre bottle if I'm going into the sticks

GRIFFIN · 2019-04-07 16:38:22

Ah well at least I know it's a more common fault than just my van. Must be a problem somewhere, I filled mine up with 40 litres of veg oil thisavo, on top of the 40 litres of diesel from the other day and when I turned the ignition on, the gauge went down to empty and the empty warning light came on. Very strange but after a drive into town and back it started reading full again. It's almost like it was reading in reverse, except I kept checking the level after each bottle of veg oil and it was fine up till almost the full mark! Good advice though, next time I'm in Tesco I'll get a 5ltr bottle to keep in the back of the van, thanks for that, advice well worth heeding.

Cheers, Griff.

OAT · 2019-04-07 20:36:18

The warning light coming on with ignition is only confirming that the warning light circuitry is ok. It doesn't check the sender.

I would expect almost any change to the shape of the tank would render the original sender useless.

As someone who regularly (and for no sensible reason), runs tanks low, I have noticed quite often that when eventually refilled, the gauge stays on empty until I hit a bump or two. I assume the float is temporarily sticking at the empty level.

GRIFFIN · 2019-04-07 23:55:48

Yes Oat, as I said in the original post, the warning light comes on with the ignition and yes it only confirms that the bulb will light up when the sender tells it the tank is empty. I was confirming that the circuit for the warning light was working so that everyone would realise that the bulb was not at fault.

However as I said in todays post, the gauge was ok as I kept checking the level and it was fine until it was completely full, then the empty light came on and the gauge indicated empty but before I poured the last 5ltr bottle into the tank the gauge read correctly. So the float would have had to sink back to the bottom of the tank in order for that theory to hold water (or in this case vegetable oil) smile

Could anyone post a photo of there fuel tank in an unadapted van? I will also post a photo of mine as well to see if the disabled access van has indeed got a different tank and in what way it differs.

Cheers, Griff.

Ricko · 2019-04-09 07:34:01

The gauge tends to drop quickly towards the end, i.e. doesn't appear to be linear

vaz2121 · 2019-04-09 21:03:27

Ricko wrote:

The gauge tends to drop quickly towards the end, i.e. doesn't appear to be linear

I agree totaly..... I show half tank but takes about 55Ltr to fill and at a quarter last time IIRC it was around the 70Ltr mark .................. So seems my guess is correct that I don't have 100Ltr tank after all ..................

I thought I'd got a pessimistic Gauge in the Binnicle change ........................

Last edited by vaz2121 (2019-04-09 21:06:19)

kenbw2 · 2019-04-09 21:20:14

Before mine started playing up, I found it to be fairly reliably:

1/4 = 10 litres
1/2 = 30 litres
3/4 = 50 litres
4/4 = 70 litres+

OAT · 2019-04-09 23:01:08

Mine's like Ricko and vaz's.

I don't actualy check the numbers but find the first indicated "half" tank is far bigger than the second. Feels good with a full tank till you think you must have a leak as it later starts emptying so fast.

kenbw2 · 2019-04-09 23:33:47

Yea I notice the first half goes loads slower.

I need to be aware of the litres so I know how much veg is in there for when I need to mix some diesel in

ruston · 2019-04-10 20:51:07

Every disability converted vehicle I have come across, car or van and any make, have nearly always had the fuel tank reduced but the same sender is used. Two neighbours had converted Vauxhalls and both ran out of fuel while the guage read half full, seems to be normal and something you just have to get used to?

GRIFFIN · 2019-04-11 13:24:11

The plot thickens, I put 45ltrs of diesel in mine and then topped it off with Veg oil and I managed to get 10 5ltr containers in and it wasn't at the top of the filler. So I'm thinking my tank must be 100ltrs when all the info I can find says the standard one is 80ltrs.

I can't get a good camera angle under the van, so I found aphoto on the web and my tank is like this one. It runs centrally lengthwise from front to back with a really long filler tube which probably holds an extra 5ltrs or more.

GRIFFIN · 2019-04-12 23:54:17

Just to confirm, it is definitely 100ltrs. I brimmed the tank tonight with diesel and managed another 9ltres, so that is 104ltrs in total, 100 in the tank and about 4litrs in the filler between the tank and the fuel cap. At a theoretical 40mpg my reckoning would give me around 915 miles on a tank. I'm gonna equip myself with a 5ltr container of 50/50 diesel and veg oil and run it till empty. I'll report back and let everyone know how far I get.

Now I'm wondering what is the farthest anyone has managed on a full tank of fuel? Answers down below please big_smile

Cheers, Griff.

Lingotto · 2019-06-18 19:46:44

Hi,

I had similar problems with my Scudo (2001). Over many years the fuel gauge had always been very accurate and the low tank light illuminated correctly, I had many times run down to 'empty' on the gauge without running out of fuel. I did however start to run out of fuel periodically, at times with the gauge showing nearly 1/4 of a tank with the gauge then seeming to regain some accuracy for a while. As I suspected the sender unit I replaced it but the inconsistencies remained, I tried a spare instrument cluster with no improvement in the accuracy either. Then I noticed that the readings on the gauge seemed to be higher in periods of wet weather sometimes increasing by several units without adding fuel, suspecting that the sender unit was being corrupted by water ingress increasing the resistance and therefore the reading shown. I remembered that a couple of years before the gauge started to give problems one of the two wires from the sender unit in the connection in the wiring loom which is fastened to a small bracket on the 'chassis' below the near-side (in the U.K.) sliding door had corroded completely through and stopped the gauge working. I had removed the connection block completely and re-connected the wires together restoring it to working order. Suspecting this might be a clue I re-cut the wires and stripped back some of the insulation where the loom had failed previously to find that the vast majority of the strands of the wire beneath were corroded black, I continued to strip back the insulation and each time found black strands of wire beneath, the quality of the wires didn't improve until I had stripped to within a couple of inches of the sender unit, I also stripped insulation from the wires running forward from the connection block and found the same corrosion, although it wasn't affected so far before improving to copper coloured strands once more. I rewired this section of the loom with new cable of the correct size and it appears that the gauge can be trusted again.

GRIFFIN · 2019-06-19 10:59:02

OK that's a great help, Its always good when you can narrow down the search. I must admit, I'd have done the same thing, Changed sender and then cluster but of course there are yards of wire and loads of connectors in between the two, which are fine when new but unlike a good wine, do not improve with age.

I'll have to get underneath and report back.
Cheers, Griff.

dispatch dave · 2021-07-17 10:25:40

Mine is showing empty when I turn on and if I tap the gauge it goes to half a tank then goes back to empty is it the gauge playing up??

GRIFFIN · 2021-09-09 01:15:10

Hmmm, sounds like it is. I'd pull the cluster out and have a fiddle with the wires, just in case it's a bad connection. It may also be worth filling the tank then tap the gauge again. If it reads full when you tap it, at least you will know that it isn't the sender unit.

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#1 2019-04-05 02:15:12

FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#2 2019-04-06 22:07:22

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#3 2019-04-07 08:08:26

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#4 2019-04-07 09:45:29

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#5 2019-04-07 16:38:22

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#6 2019-04-07 20:36:18

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#7 2019-04-07 23:55:48

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#8 2019-04-09 07:34:01

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#9 2019-04-09 21:03:27

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#10 2019-04-09 21:20:14

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#11 2019-04-09 23:01:08

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#12 2019-04-09 23:33:47

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#13 2019-04-10 20:51:07

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#14 2019-04-11 13:24:11

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#15 2019-04-12 23:54:17

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#16 2019-06-18 19:46:44

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#17 2019-06-19 10:59:02

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#18 2021-07-17 10:25:40

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

#19 2021-09-09 01:15:10

Re: FUEL GAUGE NOT ACCURATE & FUEL WARNING LIGHT NOT COMING ON

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