Fuel pump failure

[ethelred the ready]

I thought I would share a fuel pump issue I recently had. My 1.9 DG usually runs on LPG but I occasionally switch to petrol to make sure it still works. I recently did this and it wouldn't run on petrol (at a junction when the lights turned green of course!) Started diagnosis yesterday, and the fuel pump was delivering fuel but very slowly. Checked the pump rod length and it was only half millimetre short so not that.
When I compared the fuel pump (I fitted it 3 years ago) to a new one I had on the shelf there only difference was the arm that sticks out the base of the pump protrudes by 1mm on dodgy pump, about 3 mm on new one. New pump fitted and it runs great on petrol again, and switch's over much faster. I guess the lever on the old pump must have bent from fatigue.

I am going electric when this one fails, but worth checking protrusion of arm below alloy casting if you having fueling issues.

[Moonrakers]

There's probably no real need to go to the time, expense and trouble of modifying the fuel system and going electric in the pursuit of basic reliability, is there? Just stump up for a quality mechanical pump instead of the rubbish cheapo pattern ones. Brickwerks have the good ones - much pricier than the cheap option but when you see / handle them side-by-side the difference is very clear - should last decades, not a couple of years.

The original pump on my van lasted 70,000 miles and nearly 30 years (and still works fine, though has been retired as a spare) so there's no reason that the original system can't be reliable and deliver decent performance for the life of the van...

[CovKid]

No, but theres merit in pointing out the somewhat fine tolerance of mechanical pumps that can render one inoperative. I have an electric pump but remain a fan of the mechanical ones which (in good fettle) can last many years. Its design has remained relatively unchanged although all those available now are modelled on the cheaper Brazilian versions that appeared in the late 70s and for all I know, are still made there. Prior to that you could change the diaphram in them relatively cheaply by just undoing screws on the top.

On the plus side with electric ones, you can isolate the fuel line simply by removing power to the pump which can work well as way to disable the engine. They also keep up better with demand although without regular inspections of the fuel line, the increased pressure in ageing fuel hose can increase the chance of a fire I suppose. Good maintenance is key with both.

The principles of the mechanical pump are as old as the hills but sadly they are now 'units' and all you can do is replace them when they begin to fail. The same applies to electric ones and it makes sense to carry a spare really. They're not the sort of thing you're likely to find at a roadside garage.