noisy front fuel pump and iffy starting on diesel 75
 

The fuel pump beside the diesel filter on my 75 is making a humming noise and vibrating a lot .sometimes the car doesnt want to start . Is this a sign that the pump in the tank is giving up ? How do you know if its goosed ? Mrs is giving out about reliability on the car now lol.

Noisey fuel pump
 

Sometimes they just make a bit more noise however if the engine is reluctant to start together with noises, its a sure thing your in for some spending. How much depends on a couple of facts, they are-
Is the in tank pump working? this is tested by opening up the fuel filler cap, putting the ignition onto position 2 and listening to the filler neck of the tank to detect a buzzing and or swirling noise, that assumes there is a good amount of fuel inside. If such noises are present, thats a good sign that the tank pump is functioning. If its not, you probably have two pump issues. The engine will run if only the under bonnet pump is functional assuming there is over a quarter of a tank of fuel, this is because the tank has 2 compartments (Divided in the centre by the floor tunnel) The in tank pump delivers fuel from the drivers side to the passenger side, and the under bonnet pump draws the fuel from a port on the passenger side. Thus less than quarter of a tank lets the fuel stay on the wrong side of the outlet port allowing air into the system.
If the under bonnet pump loses pressure or fails, everything grinds to a hault, and then its game over! If the in tank pump failed some time ago this will contribute to the early retirement of the bonnet pump.
Worst case is that both are tired both of mine got replaced with used working parts for around £60 and some time working in diesel, but new gets expensive. DMGRS shop is good and Mat knows his stuff.
Sorry its long winded, but its easier for you to get a good description to best help you.
Cheers John.

It doesn't actually work like that. The reason the system fails with less than a quarter of a tank of fuel onboard is that the top of the ITP is uncovered as the fuel level drops, and if it isn't running, the self bleeding ball valve on the top of the ITP will be open, so air is drawn in and the UBP can't draw any more fuel out of the tank. ;)

If you look at a TD4 Freelander with the same engine it also has an ITP, but it has a flat bottom tank with no saddle.

Great info lads . Thanks .

A mechanic who was doing the tracking said it sounded like the pump has air in it , can it be bled at the pump ? . It started acting up when I last had the filter off .

They're self bleeding - the circulation of fuel should push any air out of the system.

It wouldn't be the first noisy pump I've heard that although still works doesn't intermittently provide enough fuel pressure to start.

If the in-tank pump is working and if not there's plenty of diesel in the car then suspect the under bonnet pump ;)

Of course there's other fuel related issues that can cause poor starting, injector leak-back, collapsed fuel filter, HP fuel regulator for example ;)

Russ

I had exactly the same issues with my diesel a few weeks ago, it was the in tank fuel pump failing. The under bonnet pump was running fine but was noisy, so I changed both. Front one is relatively easy to change, rear one is harder but I did it and am not a mechanic, takes some patience though, quality rear pump about £70, you only need the pump, not the whole assembly it fits into.... front pump about £30, but you can pay more! If you take out the rear pump, make sure you note where the assembly fits into the tank, I didn't and it was only with the help of the pics I got from the pump vendor that I worked it out!!!

It's a tricky exercise isn't it :D

Iffy starting......
 

If this has happened shortly after fuel filter change, maybe worth checking if the seal is ok, the system will self bleed assuming the system integrity is good, if it can draw up air and fuel the engine will strugggle like a bitch.