Hi there,

I've been trouble shooting a problem with my fuel system for a while now with no results. I have a 2000 Disco SE7 withe NAS fuel tank. there don't appear to be any codes.

What happens:

Whenever I go to the fast station to fill up, the tank will fill for a few seconds and then fuel will burst out of the filler hole under pressure. I can fill it from a jerry can, but not from the pump.

What I have done:

I disconnected the various hoses from the filler tube (I have the NAS system) but it made no difference.

I blasted air into each hose and there seemed to be no blockages.

I dropped the tank and removed the filler neck for better inspection, everything seemed fine.

I soaked the tank pressure sensor in carb cleaner, no changed when everything was reinstalled.

I disconnected the charcoal solenoid line to see if that was the culprit; no change.

I swapped tank pressure sensors from our other disco and there was no change.

I removed the tank pressure sensor all together and all of a sudden I could fill the tank, though fumes leaked out of the hole as you can imagine.

I checked all fuses under the steering wheel and everything is good.

I checked the wire harness and wires and they seem fine as back as i could trace them.

I am at a loss as to what the problem is.

The next step would be to test the wire harness somehow I guess, or find out if there is a relay or something for the sensor. I could pump gas with the sensor removed, but does that isolate the problem, or did it work simply because there was a hole when filling and the problem is still elsewhere.

The tank pressure sensor is mounted on the pump assembly and has a little hose attached that connects to the filler tube assembly but vents directly to the atmosphere under the fender.

Any ideas?

 

 

I'm with Cody.. Maybe try a slow station?

I would think it is something mechanical is going on -- the air that is in the empty tank is not being vented out properly which is causing your situation.

 

Thanks for the input so far. Its definitely not the gas station as its the same thing at any station. Also, it is very much the venting of air from the gas tank, I'm just unsure how to proceed given all of the troubleshooting I've done so far.

 

When you yanked the tank for more inspection, did you check the hoses again that you had blown air into? You said "seemed" to be no blockages but was it confirmed?

Also, have you tried pulling out the gas nozzle a little when filling to help with some of the vapors to escape?

 

I had the tank out and the entire nozzle unit. I confirmed air moving through hoses by blowing air in them and seeing it come out the other end.

It is 100% not a nozzle issue. I have 2 Discoverys and I have taken them both to the same gas station, one will fill, and one will not.

Anyone have an idea how to check if power is reaching the pressure sensor?

 

what if the tank is full? and your fuel sending unit is not accurate? unlikely but its possible

 

The tank is not full, I dropped the tank to check it out.

After some thought, there is not enough pressure from filling to activate the tank pressure sensor, it's more for atmospheric changes I think. Also, the vapour nozzle is small, too small to vent all of the pressure when filling fast enough, so lat leaves the filler assembly.

At this point I'm thinking that the holes at the top beside the fill hole must be clogged. Gas comes down the centre tub within a larger tube, which I suspect allows air to escape from that tank back up the fill tube and out of the two vent holes.

I will check them out and report back so at least this thread may help someone else given the absolute lack of info on the issue.

Thanks so far everyone

 

I can fill up my 2001 Disco 2 everywhere except for at Safeway stations - there it would take me 15-20 minutes or so - and that is the newest station built in my area

 

That is your Rover telling you that you should never feed it supermarket gas!