ERATIC FUEL GUAGE PROBLEM ON HDI

[jata23]

I have a few electrical problems with my hdi s(90) which i have owned since new, the most annoying one is when i fill the tank to the max the needle drops to about halfway after i have done approx 150 miles and when it has reached the reserve point or just before i have done approx 250 miles, and then the needle jumps back to the halfway mark.
i havent had it checked out but the trip computer is telling me that i am averaging 34mpg.(full tank produces 400miles mixed driving)
how do i know what the problem is, i have phoned pug and they advised me that it is very likely that the fuel tank sender is at fault., they also said it is expensive to repair as the fuel tank needs to be taken off.
is there any way i can check myself what the problem is.

[mjb]

Two 'R's in "erratic" dude Can you tell I'm drunk?

The fuel gauge issue stands a high chance of being a broken "lump" in the fuel tank. Unfortunately I think this "lump" includes a fuel pump as well as the fuel gauge thingy... I hope someone else can shed more light on this than I can. I'm under the impression the fuel gauge sender is the same part as the (a?) pump. A 2nd hand part will be MUCH cheaper than a dealer replacement though!

The trip computer doesn't use fuel levels to consider MPG - it uses the driveshaft speed sensor to work out distance, and the engine ECU to work out how much fuel's being injected into the engine per second. It doesn't reference the fuel level at all, so if it looks about right, you can consider it correct - more so than the fuel gauge on your dashboard!

I don't think the work involved is as painful as the dealer reckons, but others here should be able to shed more light on this than me. If you fill in your location in your user profile you may end up with a member saying "oh, I'm only 5 mins away, I can have a look for you"

[hammerman]

I think the sender is incorperated in the fuel pump.Lift up the rear seats,& there should be a round cover.Under there is the electric fuel pump that pumps the fuel to the engine high pressure pump(on the 110`s anyway).I`m sure the sender is built into the pump.The fuel pumps i`ve seen are from £20 s/hand,& from £80 new,ebay,Euro car parts etc.I think its a simple diy job to change.

[Doggy]

Some of the later HDi 90's have Siemens systems rather than Bosch & don't have a lift pump. (I think you can tell fairly easily as the Siemens jobby has a priming bulb in the LP fuel line like the old TD's had). I'm guessing a sender for one of these should be cheaper than one with a lift pump, but I think someone said the got a lift pump from GSF for £69 recently?

[BruceT]

The wagon had the pump replaced just for the sendor...

Was about £200 all in, but that was fitted as I hate getting diesel on me lol