Replace your Td5 in-tank fuel pump

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By Trevor Cuthbert

01 February 2019

Td5_Fuel_pump : credit: © Td5_Fuel_pump

Removing the Defender rear fuel tank to replace the in-tank pump is a difficult job, but Trevor Cuthbert knows a short cut

Model: Defender 90 Td5
Time: 4 hours
Cost: Genuine replacement fuel pump (WFX000250G), from £249; Aftermarket Fuel Pump (WFX-000250R), £99.57, supplied by BLRC Ltd
Difficulty: 3/5 stars
Tools needed: Drill, drill bits, hammer, screw drivers, scoring tool /pen, angle grinder (115 mm), measuring tape, steel ruleor square.
Work safely: Ensure a fire extinguisher is available and close; beware of sharp edges; wear protective gloves when working in the cut aperture.
Contact: BLRC Ltd, Tel: 02897 511763, blrcvehiclespecialist.co.uk

 

In common with many vehicles, and with Land Rover products in particular, the Defender Td5 models have a fuel pump within the fuel tank itself. In the case of the Defender Td5 the in-tank fuel pump unit incorporates the fuel gauge sender, including the float, and the associated wiring harnesses for both systems. So the part is a self-contained unit which is very easy to change, but only if there is access to the top of the fuel tank, which is not the case in the Defender.

The in-tank pump unit can fail in a number of areas. The fuel pump can stop working completely, the pump can become weak and ineffective (delivering less than adequate fuel flow) and the fuel sender unit can fail or become largely inaccurate. It is for one or more of these reasons that a Land Rover owner might need to change the fuel pump unit.

The Td5 models of the Discovery 2 have a service aperture in the boot floor, to reach the pump. The carpet and sound insulation material is pulled back to reveal a neat circular metal cover held in place by a series of screws. Removing this cover allows access to the fuel pump unit and the ability to remove the unit for replacement with a new one. Unfortunately the Defender does not possess this service hatch and the complete fuel tank needs to be removed to change the fuel pump unit, so it’s quite an involved job.

Removing the fuel tank from any vehicle can be a tricky and awkward business and no less so in Defenders. If a vehicle lift is available, the job is easier (than working on the floor) but it is still an involved process. The tank will have a number of links to the Defender body and chassis that will need to be undone – fuel filler hose, fuel breather hose, secondary breather hose, fuel feed hose, fuel return hose. That’s four fuel hoses in total on the Td5 – and then there’s the electrical harness connections for the
fuel pump and fuel sender unit. This all takes place with components that are usually very dirty and restricted, so connections can often only be broken when the tank is half in and half out of the chassis. The tank will also be bolted or strapped in place too, or at least cradled in a carrier or guard that will need to be removed.

In order to change the fuel pump unit in a Td5 Defender, there is an alternative to the arduous job of removing the fuel tank. This alternative is to cut a service hatch in the load area floor, directly above the fuel tank unit, and then to make some form of cover, to make good the hole that has been cut after the pump has been changed. Cutting this service hatch requires great care and attention because it is all too easy to damage expensive items under the floor in the process. There are also obvious and significant fire risks making cuts around any fuel system, which doubles up the need for taking great care. Potentially, damage could occur to the plastic fuel tank itself, the four fuel lines that run to the fuel pump unit and to the wiring harness that serves the fuel pump unit.

For these reasons we recommend that you do not undertake this modification if you have any uncertainty about controlling a drill, or controlling a cutting tool – particularly in terms of controlling the depth that these tools progress into the material. It is easy to drill a hole in aluminium or steel. But, when the hole is complete, have you noticed how the drill can lurch down, away from you and momentarily out of control? If this happens, you could be removing the fuel tank anyway (to fit a brand-new one), or replacing damaged hoses – or worst of all, trying to extinguish a fire.

On a positive note, once a service hatch has been successfully fashioned, it will be there for the rest of the very long service life of your Defender, should the fuel pump unit need to be replaced again.

 

Marking the floor area to cut out

The old adage applies here – ‘measure twice and cut once’. It is easy to mark up the load area floor of a Defender for cutting, but the lines that are drawn or scored must be in exactly the right place. For the purposes of measuring and subsequent marking of the square to be cut out, two datum points are used: the rear edge of the load area, and where the left hand side wheel box meets the floor. These are the points that were measured from to mark out the 230 mm x 230 mm square that was to be cut out.

This Defender 90 has a rigid plastic rear body liner fitted, which clearly needs to be removed to access the floor of the load area.

After the load liner is removed, the original factory-fitted carpet is still present, although it has seen better days. This also needs to be removed or peeled back.

With all of the coverings, the floor of the load area was well protected and it is in good condition. You will find pairs of spot welds along the middle.

We need to cut out a square of the floor directly above the fuel pump unit in the correct location. These dimensions will be used to mark the place.

This old large steel square and a tape measure were used to locate the first line, measuring from the rear edge of the body tub.

Again using the square – or any other method to accurately mark a parallel line – a second (forward) line was scribed in the floor of the rear load area.

To complete marking the area to be cut out, measure out from the left side wheel box, ensuring any remaining carpet does not ruin the accuracy.

The straight sides of the square were scribed by gouging the paint with a sharp pointed tool, but on lighter coloured paint, pen or pencil could mark the lines.

The four sides of the square are clearly marked on the floor at the correct location, directly above the in-tank fuel pump unit sitting below the body.

 

Cutting out the aluminium square

There are many methods. A series of small holes drilled close together around the marks would weaken the floor, and the remaining notches could be snipped through with sharp pliers. This would leave an untidy and uneven aperture.

A small craft tool (Dremmel) would certainly be slow and controlled. An electric jig or a reciprocal is unsuitable because the blade would destroy the tank and associated components below.

I favour the method of marking the four corners of the square with a 10 mm drilled hole, then slowly and carefully cutting along the lines with a cutting disc on the 115 mm angle grinder. I purposely use cutting discs that have worn to a smaller diameter to restrict the cutting depth and keep the job slow and steady.

Using a 10 mm drill bit, the corners of the marked out section are very carefully drilled through, using a slow drilling speed – this is very important.

A hole is slowly drilled at each corner, ensuring the drill does not slip down as it cuts through. Things below are very close below and easily damaged.

I use a cutting disc on the straight sides, without letting it plunge through the floor. Small diameter (used) discs allow controlled cutting.

Worn discs are not normally recommended, but the aluminium is relatively easy to cut, and it means the disc can never cut too far below the floor.

The four sides of the square have been successfully cut through, yet the square is still held in place. Do you remember those spot welds in step 3?

Within the square that we want to remove, there will be at least two spot welds holding the aluminium floor section to support structures below. 

Using the 10 mm drill bit, the spot welds are removed, drilling right through the support structure below, keeping the drill under full control,

A longitudinal aluminium strengthening section and a crossmember are revealed, which both block removal of the pump.

There are fuel hoses and an electrical harness in very close proximity to the supports we need to cut out. The utmost care is needed here.

The aluminium support section is an easy cut and it is possible to move the hoses and harness slightly to keep them clear of the cutting disc.

The crossmember is trimmed down. Cutting it out would reduce structural strength in rear body. A steel plate helps protect pipes and cables. 

By simply cutting out this short lip of the steel crossmember, most of the strength is retained because the strongest section is still intact.

A vacuum is used to suck away dirt, and the swarf and grindings we’ve added, to prevent it dropping into the tank as the pump is lifted out.

 

Removing the fuel pump

The hardest part of the job is now out of the way and removal of the fuel pump unit is relatively straight forward and easy to achieve. The wiring harness is unplugged and the four fuel hoses are disconnected – all are eased out of the way of the fuel pump unit.

The metal ring that secures the fuel pump to the top of the fuel tank can be very stiff to unscrew but there are metal notches around the top of the circumference, which are ideal for tapping the ring carefully around using a screwdriver or similar and a small hammer. You’ll notice some of the following pictures are from another (pick-up bodied) Defender – its white pump shows clearer detail in the pics.

The power supply to the fuel pump, which incorporates the fuel gauge sender cables, is unplugged from the fuel tank by pressing in sides and pulling.

There are four colour-coded fuel hoses to detach from the fuel pump unit. Take a careful note of the order, left to right, for accurate refitting.

These bent-hose pliers were used to help unplug the hoses, when squeezing the outer coloured tabs by hand was not quite sufficient to release them.

The fuel pump unit retaining ring unscrews counter-clockwise. The raised tabs along the top facilitate gentle tapping to aid removal of the ring.

The fuel pump unit is now withdrawn from the tank, allowing fuel to drain back in, and the replacement is installed taking care to avoid dirt entering.

To prevent dirt and water pooling in the top of the tank (especially in the pick-up) sealant is generously applied before the new cover is fitted.

This pick-up is a work truck, so a 5 mm thick square of chequer plate aluminium was used to make a heavy-duty cover.

A thinner low-profile aluminium cover is fitted to the Station Wagon as its strong load area liner will provide sufficient strength and wear-resistance.