JD 6900 fuel tank "overflowing"

[Wigeon]

Recently took the fuel tank off to give it a good clean, new lift pump and new hoses. All good now except this:

Tank is only half full, but cap seems full of fuel and its leaking out of the top. Obviously pressure related somewhere, but not sure what I've done wrong- any ideas much appreciated!

Thanks

 

[glasshouse]

Recently took the fuel tank off to give it a good clean, new lift pump and new hoses. All good now except this:

Tank is only half full, but cap seems full of fuel and its leaking out of the top. Obviously pressure related somewhere, but not sure what I've done wrong- any ideas much appreciated!

Thanks

You have that fendt problem, making too much fuel.

 

[Drillman]

You have that fendt problem, making too much fuel.

Was about to say has it been repowered with a Fendt engine?

Be doing 29mpg as well if you check I bet?

 

[davidroberts30]

Breather at the back blocked ?

 

[Wigeon]

Breather at the back blocked ?

Err, which breather...

 

[davidroberts30]

Err, which breather...

Maybe you haven't got 1?
Case and mf here do

 

[solo]

If you do a search for pressurised fuel tank on here it may give you some ideas. I don’t know how to do a link. Most common theme seems to be porous rubber fuel lines or fuel filter seal missing.

 

[Simon Chiles]

@Wigeon. The JD 6410 and 6910 had a diaphragm on the injection pump to increase the amount of fuel in relation to manifold pressure. When the diaphragm failed it would pressurise the fuel tank and give your symptoms. Does the 6900 have the same diaphragm? If it does it is possible to source just the diaphragm and replace it, you don’t have a new fuel pump.

 

[TripleSix]

Is it not a knackered seal on the cap and it's just splashing out?

 

[NZ Tech]

The fuel filter and water separator has its oring between it?.

The fuel tank steel insert isnt loose??.

 

[Wigeon]

The fuel filter and water separator has its oring between it?.

The fuel tank steel insert isnt loose??.

Thanks, will check

 

[Chae1]

Thanks, will check

Do you have another tractor with same size fuel cap? Try swapping them.

 

[PostHarvest]

I had the same problem with my JD 6220 which has a similar fuel system to your 6900. The suction hose from the tank to the fuel lift pump is probably perished due to bio-diesel and its drawing in air with the fuel. JD wanted £90 for a length of fuel hose. I bought a piece from a hose specialist www.advancedfluidsolutions.co.uk for a £few and it solved the tank pressure problem and the engine has more power than its had for a while.

 

[Wigeon]

Interrsting, thanks. New hoses, but I'll check clips etc.

 

[Wigeon]

Solved it- was leaking at the join of the return hose where it comes off the metal pipe at the back of the engine. No idea why that pressurises the tank, but no matter- problem solved!