fuel problem false tank reading
I used to be able to run my 463 right down to the bottom of the tank with no worries(but the reserve light never lit) recently however anything less than a 1/4 of a tank ( on the guage) results in a fuel starvation going round twisty roads. :shock: Is it possible for the fuel pick up to get blocked, is there a filter at that end? Any ideas?
I am only presuming so on the 463 being similar if not the same as the 460. The only time I have broken down was after rescuing a discovery out of snow. luckily he had gone otherwise my sarcastic comments would have bounced back at me... :oops:
in the back behind the seats area there is a little hatch with 4 screw undo it you will see the tank sender it needs turning a quarter turn to remove. care fully pull out what looks like a long tube which is the sender on the bottom of it you will find a gauze filter mine was blocked thick with a black oillike goo... :shock: this can be removed and cleaned with petrol or such like
it starved engine usually after driving at speed as it was trying to suck but also after a few twists and turn roads.. :roll:
The black gunge is algae of some type which grows in diesel fuel tanks. It needs to be killed or it will continue to block up filters. There's a fair bit about the subject on various websites, but I don't have any links.
Took the sender out which seems to contain the return pipe, a lot of black gunge around the sender which I presume ment the float could not move properley.Only problem now is reserve light stays on even with half a tank. Where have I gone wrong?
Also in the supply pipe(463) is there a filter that is accessible on the tank end, i think it picks up from underneath the tank. Can anyone check on their EPC?
There is a non return valve in the supply line according to the epc. I looked for it once but couldn't find it. Can you describe where it is or take a pic. They cost circa £20. Its unlikely to be blocked but you could check it easily. My low level light comes on when I turn on the ignition but goes out when the engine is running -if there is more than 1/4 tank
Thinking about this it could be the non return valve has failed.As when I have half tank you go round twisty roads no problem but when it gets towards the bottom end it comes to a halt on twisty roads but will restart once it is level again and the fuel has had tome to come through.
Anyone any idea where this valve is actually situated?
Solved the problem of reserve light staying on. Stupidly I didn't align the big silver sender unit( held in plaice by a tiny 5mm nut) but now it is properley aligned the light works as it should,
I had that problem with apparent fuel starvation occuring with the gauge markng 1/4 tank on a 1991 G-Wagen, but never really go to the bottom of it. This was a 463, 300GE and even replacing the fuel sender unit did not help.
Now my friend seems to have similar symptoms on a 2001, G400CDi. We checked the sender unit and it seems fine and there's no black gunge anywhere in sight- looks all clean in the tank.
The engine would die under acceeration getting progressively worse until it refused to start completely. The guage was showing slightly less than 1/4 and starting required a long period of cranking of about 20- 30 secs and sometimes 2 or 3 attempts. We checked all the electrics but found nothing obvious. Then, because these symptoms are similar to running out of fuel, we added 10 litres of fuel and the engine started up after 20 secs (re-priming?).
Then, having added another 10 litres of fuel, the gauge showed nearly 1/2 tank, which seems to imply that either the sender is still not correct, or it wasn't empty before?
My G came with a reserve light that was permanently on.. tank strap broke so I am doing a little R&R there. Found out that the dreaded black gung had managed to cover most of the lower sender mechanism .. the end of the sender had light rust but I found the black gunk or something under the fibre washer at the bottom under the nut inside was conductive. (not the outside nut). This was making the warning light glow about 80% on all the time. Removed washer, used air to blow it all out and now it works fine.. refitting tube was a fiddle as it is handed in all senses so look carefully before trying to force it all back together.. and those wires inside are very fine so no ham hands inside.
PS why is the tank draining plug covered by the crash/cover plate
PPS why does the tank draining plug have a filter on it... why would you want to stop gunk coming out?? .. My Lancia had this so that the filter was the bottom of the pickup so you could clean it that way but this one ??
What sort of s--- do they sell for diesel over there, dosnt seem to be the same problems on this side of the water, mind you mabey we do not keep cars long enough, ( mostly ) due to too much salt and govt mot stations.
Marcus
Some photos of that sender unit in the tank of a 463 petrol, disassembled too. Reminds me next time to look for any deposits INSIDE that aluminium tube, that might cause some friction and hence inaccurate readings. Though it seems an electrical problem more than anything, because when driving on bumpy roads at speed, the needle jumps nicely, so I guess one day I will have to go under and trace the connections to see what I can find.
The "expensive" MB tool copy, made of locking pliers and a door hinge, to remove the unit from the tank (the hardest bit was removing the tube that feeds the fuel pump, very inflexible).
This was mine: :x It first came to light after driving at speed then deccellerating. It was causing a vacuum in the fuel pipes :shock:
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Thanks I'lll try that! It certainly sounds that way, a few services ago the small inline fuel filter looked totally blocked with some black gunge :twisted: