P38 - Heavy duty lift pump?

Is there such a thing? Alternatively, has anybody cobbled together a franken-solution combining a decent quality, submersible 12V pump with the P38 fuel sensor assembly?

I got the car with 180K miles a year or two back, and the pump that came with it lasted about 40K miles. The replacement pump lasted less than 3 months - fitted it in July. It may have been britpart rather than genuine LR, are they known to be _that_ bad?

Since pulling the fuel tank off is a pain in the backside, I'm planning to take a hole cutter or an angle grinder to the floor under the rear seats and create an access hatch so the pump can be changed without removing the tank, a-la Disco1. Is there a good reason to not do this? If I'm going to have to change the lift pump 4x per year, I'd rather it takes 20 minutes rather than 4 hours.

I have pondered fitting a standard in-line pump (off a BMW diesel) in the fuel line under the car, and I may yet do that, but I am not sure how effective that will be considering that it will be sucking the fuel from the bottom of the tank rather than pushing it up line the in-tank pump does. Laws of physics mean that sucking pumps aren't as effective as blowing pumps, and if I'm going to do that, I should probably gut the in-tank pump assembly so the pump there isn't causing a needless obstruction.

Any words of wisdom from someone who has defeated this issue?

Gordan,

search this site, I got photos showing where to cut the floor, excellent ones, cut the floor in an hour, pump now takes 15 mins to change.

I go through a pump every 3 months but run on my home made biodiesel which I blame for rotting the pump, I buy from ebay at £42, as I was spending £60 a week on fuel so I am still saving heaps.

If anyone does come up with an alternative fuel pump I will crtainly be interested.

I used an air cutter on the floor, cut three sides so I can bend the floorpan back in place, same with the foam. Chiseling off the sound deadener was the messy bit but really a simple job.

Awesome stuff, I'm glad that I'm not the only one seeing this problem and that the solution I was contemplating is sound. I'll try to find the photos. With all the bending, the panel would snap after a few changes anyway, I'll probably cut it out completely, cut a new oversized piece of metal and bolt it in using some nuts araldited to the underside.

Gordon are you running off pump diesel or some mix of cooking oil and diesel?

It's a mix. In light of what you said on the other thread, though I'm wondering if the symptom is only obvious when the fuel level drops below 1/8 of a tank. Both times when this necessitated a tow truck was when the fuel level dropped to that level (just above where the warning light comes on).

Since that is a relatively rare occurrence (there being less than 3 gallons in the tank), it is entirely plausible that I could have been driving with a duff lift pump for more than a month - that's roughly when I noticed the power surging when at full throttle for long stretches over 2800rpm. And of course, all my testing of the symptoms would have come from times when I had reason to believe there was a problem (i.e. duff lift pump and low fuel level at the same time) - which would inevitably skew my perception.

I may just have to test this possibility by adding 80 litres of fuel into the tank and see if that "cures" the problem until the replacement pump arrives.

The odd thing is, though, it was never accompanied by starting problems beforehand. :-/

gordan said:

It's a mix. In light of what you said on the other thread, though I'm wondering if the symptom is only obvious when the fuel level drops below 1/8 of a tank. Both times when this necessitated a tow truck was when the fuel level dropped to that level (just above where the warning light comes on).

Since that is a relatively rare occurrence (there being less than 3 gallons in the tank), it is entirely plausible that I could have been driving with a duff lift pump for more than a month - that's roughly when I noticed the power surging when at full throttle for long stretches over 2800rpm. And of course, all my testing of the symptoms would have come from times when I had reason to believe there was a problem (i.e. duff lift pump and low fuel level at the same time) - which would inevitably skew my perception.

I may just have to test this possibility by adding 80 litres of fuel into the tank and see if that "cures" the problem until the replacement pump arrives.

The odd thing is, though, it was never accompanied by starting problems beforehand. :-/

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The fuel system is designed to be tolerant of fuel in a certain viscosity range. That does not include neat Asda cooking oil. A 300 TDI can be run off almost pure veggie oil in summer because it has a mechanical lift pump which automatically stops pumping when system is full of fuel. But doing that will eventually knacker the FIP. If you try that with a P38 you would destroy the lift pump in a short time. You should never have a mix greater than 50/50 diesel to veg oil even in summer and in winter 70/30 diesel to veg oil. Maybe i now understand why you talk of engine not running without lift pump. Your fuel is just too thick. Running large portions of veg oil without something in it to wash the fuel injection pump internals will cause lacquer build up inside the pump and destroy it. It will also clog your filters and build up deposites in your fuel lines. In other words it's a cheap way of knackering you car up, if you get too greedy.

the lift pump was only fitted as an effective way to bleed the system.any diesel above the 1/4 level is sucked in vai the injection pump save the cost and keepyour tank topped up then you wont strain the lift pump in tank!

defender300td1 said:

the lift pump was only fitted as an effective way to bleed the system.any diesel above the 1/4 level is sucked in vai the injection pump save the cost and keepyour tank topped up then you wont strain the lift pump in tank!

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The fuel lift pump is indeed a handy tool for bleeding the system. But it also supplies a basic pressure for the FIP. Think you will find if your lift pump is not working even on your 300 TDI there will be a distinct lack of power under load.

was not refering to the macanical lift pump on 300tdi, the eclectric pump in the p38 is a low pressure pump that comes into action when fuel level in tank is low via crank sensor Fip is fip will suck on its own steam

defender300td1 said:

was not refering to the macanical lift pump on 300tdi, the eclectric pump in the p38 is a low pressure pump that comes into action when fuel level in tank is low via crank sensor Fip is fip will suck on its own steam

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Are you sure about that. Have you been reading the same book as Gordon. The mechanical lift pump on the TDI is also a low pressure pump. The fuel pump on the P38 is powered at all times when engine is running directly from the alternator. Think you had better have another read.