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Well. The talk access is not under the battery tray, it is a bit forward under the cover that hides the 4WD stuff.
Anyway, I removed the lid and had a look inside. I see the black pipe, which looks OK, although I haven't withdrawn the whole assembly yet.
What I do see is no fuel. The tank is dry.
I guess that means the float assy / fuel indicator?
Let me know what you think. Did I hear that someone had the float arm get caught on that mess of pipes in there?
The tank has a lower level on each side. A jet pump is installed in each lower level to suck the fuel out and place the fuel into the fuel pump. When the tank is below about 1/2 there is no fuel in the top section.
When the fuel level goes below 1/2 tank the float no longer reads the fuel level. Instead the instruments guess how much fuel is left by using the fuel consumption rate. To get the fuel gauge to read the actual fuel level the tank must be at least 1/2 full so fuel is visible around the fuel pump.
It is possible you are just low on fuel and the gauge is not reading. You can check this by filling the tank a little more than 1/2 way, watching the level through the opening. Then refit the white cap and fuel lines to re-test the fuel pressure.
Since you have done so much disassembly I would disconnect the two jet pumps and remove the main pump to inspect the lines. You can also easily remove the jet pumps to inspect their lines. A leak anywhere in the lines will cause low fuel pressure.
Thanks theprf, your picture in one of your posts above - showing the whole pump assy out of the car, does that show these jet pumps, or do these remain in the tank?
i,e, do you have a pic/diagram.
I will take it all out and have a good inspect.
p.s. I've seen videos of people popping off those pipes to withdraw the stuff - is it obvious which pipe goes where - or should I carefully mark them when I take them off?
pps, I found this marvellous drawing from ksteen13 (from a Turbo though) https://cimg5.ibsrv.net/gimg/rennlis...94b09e13d2.jpg
..and this vid shows the pick-ups out of the car, which I found useful:
Should the pump run all the time? Does it switch off when up to pressure?
Is there something wrong with that pressure switch - if there is one?
The fuel pump will only build pressure for a short time, enough to start the car, but will not continue to run if the engine isn’t running. This is a safety feature.
Well. The talk access is not under the battery tray, it is a bit forward under the cover that hides the 4WD stuff.
I guess that means the float assy / fuel indicator?
All the AWD have the split level gas tank to clear the awd. The 2wd access is under battery tray, the AWD access is in front of battery under that dome cover The split level awd tank necessitates 2 transfer pumps, 1 in each side well of the tank. These transfer pumps feed the main pump.
If you're concerned with the float level sensor not working correctly, once you take out the assembly you can plug it back in and move the arm up and down slowly while someone watches the fuel gauge. This should confirm its working ok.
iirr, on awd tanks the full throw from bottom to top will only go from full to half tank. The last half tank level is computed somehow as theprf explained.
Pull this apart already, don't over think this. Take pictures of hose layout.
Once you have it apart it will all make sense and be a lot more straight forward.
If you're worried about getting your hand wet with fuel, borrow the wife's dishwashing gloves, she'll appreciate the disinfection qualities of the fuel dipped gloves...
Hello all,
you will be please to know that I have got(ten) up off my thin **** and removed the unit.
In-twist-out as we used to say in the war.
See attached pic.
I can see no damage to the pipes/hoses around the pump, nor around the two venturi pump ends.
Hello all,
I have carefully inspected all the hoses and pipes and all look good - including the ones which go down to the 'side-tanks'.
In any case, the tank is fully empty.
I took a look at the fuel gauge with my resistance meter.
As I moved the float, there were some odd readings along the way, but I guess the float will be bobbing around most of the time, giving an average reading.
I took the float off, inspected the wiper and cleaned the contacts.
There are a number of test pads on the ceramic PCB which holds the printed resistors.
Here I measured 10R, 78R, 142R and 205R at the end.
If anyone else has a float assy available (for a C4), maybe they could check.
My PCB says VDO and has the number 493 on it.
Anyway I wired it up to the car and (according to my daughter) it read from 1/2 tank to full tank as I moved the float.
I have put everything back in the car now - ready to fill up and monitor the mileage vs gauge reading carefully - with a spare can of fuel in the frunk.
If anyone has any other ideas, please let me know.
05-02-2024, 04:05 PM
