Only takes a tenner to fill my tank?!

So interesting problem has arisen with the golf. I think I know what the problem is but want other opinions. Eh basically the car can take about £10 of petrol and it's full to the brim? I thought maybe this was an issue with the breathers as 1 currently only have 1 outlet connected, the main one to the filler neck. The others still have the rubber caps. So today I went out with the intention of taking out the sender unit as it always shows as half full on the guage, figured it was in the wrong way, and top connect up a breather. As I twisted it off the sender petrol came pouring out!(the fuel cap was off at this point) I had to stop and put the sender back in as it kept coming out, car is currently sitting in a big puddle of petrol! My thinking is maybe the tank has compressed under the vaccum inside and it's bent out of shape. Seeing as I don't have any vaccum lines going to air I figure the vaccum inside could possibly do this. Any takers on this? Cars been running for ages and this problem only came up about 2 months ago. I'm going to drive it till its almost empty and try and take the unit off again. See what it's like inside.

Cheers

Jamie

i dont think you could get enough vaccum in the tank to make it change size significantly, its only single skin tank though so you'll be able to tell just by looking underneath it'll be obvious if the tank has squashed down.

what exactly is the problem here, are you sure the tank is ever actually empty before you try to put £10 in? maybe the level sender is reading wrong,it sounds to me like you're just keeping the tank almost full to the top all the time

Looking from underneath there's no change in shape but  the tank is able to move up so I'm guessing it's the top section that compressed as the straps are bolted tight. Yeah it's def not full, I've already from  that mistake. The sender is constantly at 1/2 full and one day I ran out of petrol, put a gallon can in and went to the petrol station where I could only put about £7 in and it was full. I'm going to run it it down a bit and have a look. Read I can use an airline through the return line to add + pressure to the tank and try to pop it out.

seems really strange, did it definitely run out of fuel or was it just the pump couldnt get any fuel? maybe the feed pipe has fallen off the level sender so it can only pick up fuel when the tank is nearly full?

is it a gti or carby actually, also what year

Yeah no fuel, it's got an inline pump so no lift etc. Also shook the car and no sound from the tank. If the weathers nicer tomorrow I'll get out an drive for a while to empty the tank a bit. Was a 1.1 but converted to G60.It's a new tank btw new lines pump filter. No accumulator etc just straight in and out lines.

what kind of fuel pump are you using? some of the inline pumps need a swirl pot before and a later cab/rocco/g40 shape polo lifter pump in order to work properly

CarnieMK1 said

? I thought maybe this was an issue with the breathers as 1 currently only have 1 outlet connected, the main one to the filler neck. The others still have the rubber caps.

This bit troubles me. Did you fit a new tank, and not connect everything up as on the old tank? This could explain fuel starvation due to no breather on the tank, which might be being perceived as no fuel (empty tank) when it runs out.