Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

This is the Forum for all your Citroen Technical Questions, Problems or Advice.

Moderator: RichardW

kenbw2
donor 2017
Posts: 266
Joined: 23 Dec 2014, 01:24
x 20

Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

Post by kenbw2 » 29 Jun 2019, 13:30

Since I got my new Dispatch I found it runs out of fuel at 1/4 of a tank - engine stopping running for fuel starvation. Fair enough I thought, I'll just have to be mindful of it.

I then went to fill it up, and I mean reeeally fill it, till it leaks out the top. I got 65 litres in before it overflowed. I managed to slowly get another 10 in but it wasn't taking any more

In my various other Synergie/806/Dispatches, I've been able to get at least 80 litres from drained, I think even close to 90. So there must still be fuel left in the tank it can't get to.

How would this be? I guess the feeder pipe doesn't float, so it's not getting stuck. Anything I can do short of dropping thank and looking inside?

User avatar
white exec
Moderating Team
Posts: 4701
Joined: 21 Dec 2015, 13:46
x 631

Re: Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

Post by white exec » 29 Jun 2019, 16:10

Tank bottoms (not to be confused with tank tops #-o ) have been known to distort/bow upwards when the weight of fuel decreases, and this could block off fuel being sucked out of the tank. You could inspect the base of the tank, and see whether it's possible to pull it down (eg with a suction lifter for glass).

Only a remote possibility. As you say, you might just have to burrow in there. Broken or wrong pick-up unit fitted??
Dispatch_ I _1.9TD fuel tank.JPG
The large fuel filler pipe looks as if it enters the tank right at the bottom. Wonder whether that would allow a peek inside without removing everything?

kenbw2
donor 2017
Posts: 266
Joined: 23 Dec 2014, 01:24
x 20

Re: Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

Post by kenbw2 » 29 Jun 2019, 23:55

Doesn't look like it's sagged inwards, you're right about the filler pipe. My tank's almost empty (I think...) so I'll disconnect that tomorrow and see what I can see in there

kenbw2
donor 2017
Posts: 266
Joined: 23 Dec 2014, 01:24
x 20

Re: Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

Post by kenbw2 » 01 Jul 2019, 11:46

So I ran it till it cut out yesterday, then parked in on a flat, primed it and ran it stood still till it cut out to rule out any sloshing/hill issues.

I then removed that pipe from the tank, and out poured some fuel:

Image

Given that pipe isn't the lowest point, and that the pickup is in the centre, where the lowest point is, I think it's safe to say there's still fuel in the tank that it can't get to

Image

I tried taking a look inside but couldn't see much. I also tried shoving my reversing camera in there so I could see round the corner, but it wouldn't fit :)

Hell Razor5543
NOT Alistair or Simon
Posts: 9551
Joined: 01 Apr 2012, 09:47
x 688

Re: Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

Post by Hell Razor5543 » 01 Jul 2019, 15:47

I wonder (only WONDER, mind you) if this is one of those vehicles where somebody has fitted a 'secret compartment' tank? These things do exist, and are designed to fit in the place of an ordinary (but fairly large) car component, with space 'reserved' for a secret storage space. Fuel tanks can be one such item selected for 'modification'.

User avatar
Michel
Posts: 1619
Joined: 29 May 2017, 13:50
x 279

Re: Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

Post by Michel » 01 Jul 2019, 18:23

Has someone had the sender unit out and bent it?

User avatar
white exec
Moderating Team
Posts: 4701
Joined: 21 Dec 2015, 13:46
x 631

Re: Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I s

Post by white exec » 01 Jul 2019, 21:48

Or fitted something non-standard?
Probably best to whip the tank out, if you can't get access/visibility from the top,
At least then you'll know, and get to sleep at night...

rebuilder86
Posts: 6
Joined: 02 Jul 2019, 02:17
x 3

Re: Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

Post by rebuilder86 » 02 Jul 2019, 02:19

Sounds like air is getting in instead of fuel at the 1/4 level creating an airlock.
Pull the pump out and inspect for cracks.
If no cracks, the pump may be overheating when not submerged.

User avatar
white exec
Moderating Team
Posts: 4701
Joined: 21 Dec 2015, 13:46
x 631

Re: Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

Post by white exec » 02 Jul 2019, 08:15

Being diesel, there is no pump in the tank. The inserted unit is simply the fuel gauge sender.
Fuel taken from tank by suction. It is possible, though, that the sender unit/pick-up pipe is holed as you suggest, so a good call.

kenbw2
donor 2017
Posts: 266
Joined: 23 Dec 2014, 01:24
x 20

Re: Mk1 Dispatch - fuel runs out at 1/4 tank, and I get less fuel in than I should

Post by kenbw2 » 02 Jul 2019, 23:53

Looks like I'll be dropping the tank at some point then. I hope I can do this from below because there's no way I'm getting to it through the floor with all my campervan mods!