Replacing the Low Pressure Pump in the fuel Tank
Posted: Sun Sep 09, 2018 8:54 pm
Following on from my post here :
viewtopic.php?f=3&t=5562&p=193008#p193008
Here's what was happening at the engine end of the LP fuel rail:
Got a new aftermarket pump assembly (not just the pump, as research shows that it's best to have the new thermostat and pipework also) as well as a new tank gasket since getting back, so tackled the job this weekend.
I was using the Haynes guide for the instructions, which covered all the basics though as expected was sadly lacking in a couple of important details which I'll try and list here.
One detail was the location of the "grey" push-fit connector at the rear of the tank. There's a yellow clip connector and a grey connector but the grey one is all but invisible. I found it behind the top of the air shock turret housing, out of sight from the wheel housing and difficult to get the hands in to put enough pressure on the push buttons (it was full of mud, go figure?). Removing the spare wheel brought it into view and allowed a mini set of water pump pliers to press the tabs.
All six bolts holding the tank in were corroded in place, so lots of shock and unlock fluid used to get them moving. Eventually dropped the tank using a jack and was able to reach in to the front fuel connectors. And that's where everything was different to the guide again, as instead of two push-fit connectors to undo, there were four, the extra two were connecting to the 2007MY onwards fuel filter housing.
I also disconnected and removed the FBH fuel pump as it looked like this would foul the tank during removal.
After another 20 minutes jetting with a high pressure air line the rock like mud was blown out of the electrical connector tabs on the top of the tank and it was eventually able to be removed.
It's not in any guide but the front left top of the tank has a black nylon shroud that bolts down into the steel undertray; this has to be removed to separate the tank itself from the bash plate.
After all that I (well my youngest actually) swept up and binned about 6Kg of mud and gravel.
The plate appears to have a slight bow to it, but I'm not sure if this is because it's supposed to be there or if I've landed it hard on a rut and bowed it.
Nah, can't have been that, right?
With the tank out there was thankfully very little fuel spillage, and I got it out to the side of the car and using a wire brush and high pressure airline cleaned the connectors on the access plate and removed it.
Oh my. So much rust/mud inside. All the white plastic was coated with a film of rust and there was some evidence corrosion on all the electrical connector spades. The worst rust was on the pump motor body itself. The pump filter screen was as nasty as any you've seen in any other posts across the interweb; covered totally in black slime and the bypass screen was also almost totally covered. I suspect this is the reason for the failure; the main filter is totally blocked, so it was pulling (less well filtered) fuel through the bypass screen, and that itself was blocked and so restricting flow.
I was surprised by the amount of metal shavings in the tanks filter. It looks like the same metal as the petrol station fuel pump nozzles are made of, some sort of zinc alloy I think as It's non magnetic.
There's a green band made out of a sinusoid shaped plastic, and this provides an elastic clamp to holding the pump module in place. There's a semicircular plastic baffle that the pump module sits against, then a further 1/4 circle that is hinged to allow the pump module to be removed, and then the green band pulls it all together. It's very solid and I cannot see it ever shifting in normal use unless you really clout the tank.
The replacement part looked identical to the original one, except the pipes headed off at a weird angle as the cable tie was obviously in the wrong place. A quick snip and a new cable tie made both parts identically shaped.
Haynes said that refitting is the reverse of removal. I really hate those words, as it's almost always a lie. It was here too. My big plates of ham simply couldn't replace that green strap and leave enough room for a torch to see where I was aiming as well as a finger to hold the 1/4 circle hinged portion closed. Took a good 20 minutes of try try try again to finally get it in place, and the same went for the thermostat housing.
Refitting the remaining connectors was simple enough compared to the effort to remove them - simple push to fit. There was one pipe that remained in the tank that just seemed to be flapping around loose. The only place I could find for this was pushed onto the stub on the access plate that connects to the fuel return from the High Pressure Pump. This was not there when I took it off, so I hope that it was the correct place for it.
That's as far as I've got this weekend; next I'll be refitting the tank and then having a look at the gearbox leak. I have a lot of bolts to wire brush and copperslip first so probably another couple of hours work in the tank before heading into the gearbox to see where the leak was from.
And yes, I did check the new pump worked before refitting it
viewtopic.php?f=3&t=5562&p=193008#p193008
Here's what was happening at the engine end of the LP fuel rail:
Got a new aftermarket pump assembly (not just the pump, as research shows that it's best to have the new thermostat and pipework also) as well as a new tank gasket since getting back, so tackled the job this weekend.
I was using the Haynes guide for the instructions, which covered all the basics though as expected was sadly lacking in a couple of important details which I'll try and list here.
One detail was the location of the "grey" push-fit connector at the rear of the tank. There's a yellow clip connector and a grey connector but the grey one is all but invisible. I found it behind the top of the air shock turret housing, out of sight from the wheel housing and difficult to get the hands in to put enough pressure on the push buttons (it was full of mud, go figure?). Removing the spare wheel brought it into view and allowed a mini set of water pump pliers to press the tabs.
All six bolts holding the tank in were corroded in place, so lots of shock and unlock fluid used to get them moving. Eventually dropped the tank using a jack and was able to reach in to the front fuel connectors. And that's where everything was different to the guide again, as instead of two push-fit connectors to undo, there were four, the extra two were connecting to the 2007MY onwards fuel filter housing.
I also disconnected and removed the FBH fuel pump as it looked like this would foul the tank during removal.
After another 20 minutes jetting with a high pressure air line the rock like mud was blown out of the electrical connector tabs on the top of the tank and it was eventually able to be removed.
It's not in any guide but the front left top of the tank has a black nylon shroud that bolts down into the steel undertray; this has to be removed to separate the tank itself from the bash plate.
After all that I (well my youngest actually) swept up and binned about 6Kg of mud and gravel.
The plate appears to have a slight bow to it, but I'm not sure if this is because it's supposed to be there or if I've landed it hard on a rut and bowed it.
Nah, can't have been that, right?
With the tank out there was thankfully very little fuel spillage, and I got it out to the side of the car and using a wire brush and high pressure airline cleaned the connectors on the access plate and removed it.
Oh my. So much rust/mud inside. All the white plastic was coated with a film of rust and there was some evidence corrosion on all the electrical connector spades. The worst rust was on the pump motor body itself. The pump filter screen was as nasty as any you've seen in any other posts across the interweb; covered totally in black slime and the bypass screen was also almost totally covered. I suspect this is the reason for the failure; the main filter is totally blocked, so it was pulling (less well filtered) fuel through the bypass screen, and that itself was blocked and so restricting flow.
I was surprised by the amount of metal shavings in the tanks filter. It looks like the same metal as the petrol station fuel pump nozzles are made of, some sort of zinc alloy I think as It's non magnetic.
There's a green band made out of a sinusoid shaped plastic, and this provides an elastic clamp to holding the pump module in place. There's a semicircular plastic baffle that the pump module sits against, then a further 1/4 circle that is hinged to allow the pump module to be removed, and then the green band pulls it all together. It's very solid and I cannot see it ever shifting in normal use unless you really clout the tank.
The replacement part looked identical to the original one, except the pipes headed off at a weird angle as the cable tie was obviously in the wrong place. A quick snip and a new cable tie made both parts identically shaped.
Haynes said that refitting is the reverse of removal. I really hate those words, as it's almost always a lie. It was here too. My big plates of ham simply couldn't replace that green strap and leave enough room for a torch to see where I was aiming as well as a finger to hold the 1/4 circle hinged portion closed. Took a good 20 minutes of try try try again to finally get it in place, and the same went for the thermostat housing.
Refitting the remaining connectors was simple enough compared to the effort to remove them - simple push to fit. There was one pipe that remained in the tank that just seemed to be flapping around loose. The only place I could find for this was pushed onto the stub on the access plate that connects to the fuel return from the High Pressure Pump. This was not there when I took it off, so I hope that it was the correct place for it.
That's as far as I've got this weekend; next I'll be refitting the tank and then having a look at the gearbox leak. I have a lot of bolts to wire brush and copperslip first so probably another couple of hours work in the tank before heading into the gearbox to see where the leak was from.
And yes, I did check the new pump worked before refitting it