Ran out of fuel - when tank 1/2-full!?

[van ordinaire]

Went to pull out from a parking space in the C15 this evening & it died: classic out of fuel symptoms BUT gauge was hovering under the 1/2 mark, which tallied with 253 miles since last fill-up. Slung in the spare 5 litres, went through the re-start diesel after running out of fuel pantomime & drove round the corner to the garage. That was my next stop anyway, to top-up, as driving back down to Devon after work tomorrow. And top-up was all I could do because despite having just run out of fuel, I only managed to squeeze in 25 litres, which is quite good for 253 miles AND suggests the gauge is pretty accurate. Sooooh, why did it "run-out" with 20 litres still in the tank?

[sparksie]

Pin-hole in a pipe, somewhere? Or leaky filter gasket, perhaps? Or even the diaphragm in the lift pump?
Allowing an air bubble to form while parked up, which gets sucked into the pump when you start up, causing the classic air-lock symptom.
Next time, bleed it without topping up.
I bet it'll work...

[white exec]

Maybe a blocked fuel filter? If a Purflux unit, in addition to the main filter element, there are one/two micro-filters (under the output banjo bolt) which can eventually block.
Water in fuel (tank or filter bowl)? Air in fuel?

[van ordinaire]

Thanks for the suggestions but why does it happen when the fuel gets to a certain level?

Air in the fuel would cause power loss (similar to a failing injector) &,in fact, it's running particularly well at the moment.

I thought about water in the tank, as the fuel would float on it,so you could run out of fuel but the gauge would be reading the water BUT, where would that amount of water come from & isn't the fuel drawn from the bottom of the tank?

Anyway, the tank's not coming out again so I'll just have to live with it - or find another van.

[white exec]

Maybe not relevant, but XM's plastic tank bottom has been known to rise up as weight of fuel reduces, allowing the fuel pick-up pipe in the tank to get blocked off. Adding extra fuel restored normal running.
Who would think...

Diesels suck fuel from the tank, so a leak in pipework is usually hard to spot. Might be worth checking out the tank for sludge, etc.

[Gibbo2286]

I suppose it's possible that the pick up pipe is too short (wrong one fitted) and gone un-noticed if you keep it topped up regularly.

[Jaf]

My Xantia used to stall about 1/2 mile up the road. Felt completely like running out of fuel, no loss of power just died. After pumping the manual fuel bulb she would run perfectly, until a few days later. Eventually it happened every day, at the same spot (it also sometimes happened at random spots when going downhill). As it got worse I found a fuel leak on the fuel filter housing.

[Michel]

Have you got under and actually checked the tank? I had a Ford Orion many moons ago which ran out when showing just under half full. Turns out the breather was blocked, and it actually sucked the bottom of the tank upwards, so the float for the gauge could only go half way down. Obviously the first time, it ran for a long time until it ran out, but afterwards I could only get 2/3rds of the amount of fuel I used to be able to get in it in.

Could be a blocked breather causing a vacuum in yours, which is fixed by removing the fuel cap..

[Gibbo2286]

Have you got under and actually checked the tank? I had a Ford Orion many moons ago which ran out when showing just under half full. Turns out the breather was blocked, and it actually sucked the bottom of the tank upwards, so the float for the gauge could only go half way down. Obviously the first time, it ran for a long time until it ran out, but afterwards I could only get 2/3rds of the amount of fuel I used to be able to get in it in.

Could be a blocked breather causing a vacuum in yours, which is fixed by removing the fuel cap..

I've had to fix a couple of those in the past Mike.

[van ordinaire]

Thanks for all the further input but, unfortunately, it serves to confuse me (as opposed to the issue) even more. Seems I know even less about diesels than I thought, i.e. nothing.

My original post was at the end of a long day, including driving down to Devon after work, in fact about 2:30 a.m. so was, of necessity, brief. Perhaps if I now fill in the history/background it might put the current problem into some sort of perspective.

I had this problem about a year ago when the gauge was reading 1/4 and I'd done about 300 miles, so that would be about right. I think it was Jim who suggested a blocked filter - but as that was a tank out job, I was in no hurry to investigate further & simply started looking for fuel when the gauge dropped to 1/2. A few months later, it started hesitating on hills (bit of a problem in Devon - particularly (for those of you familiar with the journey to Torbay) with the infamous Telegraph Hill to negotiate. That turned out to be an air leak in the fuel line, immediately obvious having cleaned a length of clear fuel line under the bonnet: not just bubbles but what I afterwards wondered might've been globules of water. Nevertheless, pulling off the fuel line to the tank & substituting a length of hose dropped into a 5 litre contained produced "solid" fuel in the clear line & an engine happy to rev with no hesitancy. Then the nightmare began: (a) the tank was all but about 1/2-gallon full, (b) the van's ply-lined, so it was about 1/2 a day's work just to disconnect the filler pipe (c) it had to be finished over Christmas. Anyway, there was no obvious leak, porosity or even any deterioration of either the supply or return hoses (but I replaced them - as I couldn't bear the thought of having to do it again). Removing the pick-up revealed no filter, but on peering into the tank there it was, lying on the bottom! When I fished it out, it was almost completely blocked. Cleaning it, taking care not to damage the mesh, wasn't easy but, eventually, it was ready to be snapped back into place. Took the sender out for good measure but found nothing obviously amiss.
So, started the New Year with all associated problems solved; all that was a little over 3,000 trouble-free miles ago, until a couple of weeks ago. On both occasions it was after it had been parked for a short time after a short drive. I was beginning to wonder if the fact it was not long after replacing the fuel filter was significant but then remembered there had been a time a week or so before when it had happened while driving - but I'd put that down to having wrongly assumed I had enough fuel for the journey.

[white exec]

OK, some additional background info, which is helpful.

Tank vacuum (blocked breather pipe)
Try running the car with the fuel cap loose or removed (wedge a bit of sponge in the filler tube, to prevent splash, if it's really full.
If you do drive with the filler cap on, and the engine fails, try immediately but very slowly undoing the filler cap, and listening for an in-rush of air. If this is heard, the tank breather is blocked. The pump will be struggling to suck fuel up, and the tank bottom could rise as well, possibly cutting off the fuel supply.

Air in fuel
All parts of the system between tank pick-up and the pump work under suction, so a leak is usually not visible, but air can get sucked in.
If you can, fit a piece of non-collapsible transparent tube between filter and pump. See if there are any air bubbles there.
Do the same on the intake side of the filter. If bubbles there, the pipe between tank and filter is porous/admitting air at a joint. If no bubbles there, and there are between filter and pump, then the filter is letting air in.
If a Purflux filter (priming button on top, tall cylindrical aluminium filter bowl), check the large O-ring between bowl and filter head. Also check the groove it sits in: I have seen a casting fault on one of these, where there was a lump (French lermp) in the groove, which prevented a proper seal. Also check the banjo bolt and pipe seals at the filter, and the drain screw at the bottom.
Air ingress can happen where worm-drive (jubilee) clips are used on small fuel lines, because most of these small clips are not perfectly circular, and can distort the pipe seal. If a bad joint is found, cut the hose back, and remake with a better hose clip.

Could be worth checking the tank pick-up filter again, to make sure it's still not detached or blocked.
Now you know how to get in there (how about a little hinged hatch in the plywood?), it should be much easier. How clean is the tank?

[MikeT]

Considering the tank strainer was clogged, could you have microbial growth in your fuel?

http://www.mycleandiesel.com/pages/Solu ... rowth.aspx

You may want to buy something like http://www.jlmlubricants.com/en/product ... 01%20litre

[van ordinaire]

As upon "running-out" I've almost immediately added 5 litres, wouldn't I have the in-rush of air then?

Most of the under bonnet fuel line IS clear but I've not thought to check because when there was air in the fuel it wouldn't pull, since I replaced the air & fuel filters it's actually running better than ever AND using less fuel! I could introduce a piece of clear hose at the entry to the filter but if it's air causing it to die/not start how can I check if it's not running?

What would air entering the system when the fuel dropped to a certain level indicate?

It is because I do know how to get into it that I have absolutely no intention of ever doing it again & no, a "small hatch" wouldn't help, you have to remove the wheel arch box & that side of the lining just to get to the floor - just to detach the filler: still got to drop the tank - no thanks!

Considered microbial growth but the filter was blocked by a relatively hard coating, not sludge everything else was clean although, possibly as a result of running without that filter for however long, the original filter element had traces of some soft, white sticky substance, which I blamed on vegetable oil. Not used that for a year now and the filter I've just replaced showed no sign of the same stuff. But, again, surely that would causing starting/running problems, not the symptoms I'm experiencing.

One thing I should have added is, when I refuel there is always a leak under the tank which I used to be able to avoid by stopping as soon as the pump cut off, rather than trying to squeeze in a few more litres, but that doesn't do the trick now. That is a recent development but predates the first apparent "running-out" incident. Now I realise that if fuel can get out, air can get in but I can hardly crawl under the van on the forecourt to look for a leak.

[Gibbo2286]

One thing just occurred to me, does that vehicle have up and down hoses i.e. a return hose to the tank?

I had a job once where they'd been replaced by the owner and he'd got them mixed up and had the return hose on the wrong connector, it would only lift fuel from part way down the tank where it ended.

[white exec]

Air getting into the tank won't be a problem; actually, it's essential (no vacuum).
Can understand why you don't want to open up the tank again, having 'nailed the floorboards down' so-to-speak.
How about just trying - once again - to run the engine from a tube (just before the fuel filter) dipped into a can of diesel? If that starts and runs without issue, you'll know the problem is tank/tank-pipework-related.
Then you can decide whether to fix it, or not.