406 hdi pump in tank problem. 2.0 hdi 110

[xsaras4ever]

Hello to all.

went to diy store, parked up 406.

Wouldn't start when we came out and we got a friend to trailer it home.

We checked all fuses under the dash and in the BSI. We disconnected the fuel pipes to the diesel filter, no fuel.

Disconnected the block to the pump in the tank - 12 volts when ignition first turned on - dropping to 2.9 after about 5 secs.

We think this is normal - is it ?

Connected a battery charger delivering 12 volts onto the pump - nothing.

Sound like the pump is shot - and its not just an issue of remove it and fit another - no - its drop the tank down - because Peugeot upgraded the pump but never enlarged the hole in the floor.

Agree or disagree ?

Thanks in Advance

[myglaren]

They will sometimes come back to life if you smack the tank where the pump is located with a 2x4.
Only a temporary revival though.

[xsaras4ever]

Thanks for that, although we have already tried that with the shaft of a lump hammer.

[xsaras4ever]

Hi MYGLAREN,

we hit it hard with a lump hammer and it came back to life - yes - only temporary but we connected it directly to a battery charger and pumped out all the fuel.

Got a new pump - 84euros including delivery - about £65 which seems good.

Car back in action.

Thanks again

[CitroJim]

Disconnected the block to the pump in the tank - 12 volts when ignition first turned on - dropping to 2.9 after about 5 secs.

We think this is normal - is it ?

Yes, completely normal. The pump runs initially to get everything primed and pressurised ready for a start attempt. If there is no start - signified by the engine failing to spin faster than a given rpm - then the pump shuts down again. It won't run again until the engine is seen to be running...

This is for safety. If the engine stops for any reason the flow of diesel from the tank stops too. Vital in case of an accident.

Petrols do the same and early injection engines had a most wonderfully named relay, the tachymetric relay, to do this very job. A source of trouble in the Pug 205GTi...

[spider]

Ah I remember those. Although (sorry) I do something think the tachy relays were sometimes less trouble than the newer alternative method.

I remember the 504 (or 505?) where they tachy lived on the steering column. "straight down the middle" (the three wires) to bypass, not safe though but an emergency "get you home" thing (with care)

[CitroJim]

I remember the 504 (or 505?) where they tachy lived on the steering column. "straight down the middle" (the three wires) to bypass, not safe though but an emergency "get you home" thing (with care)

That's roughly where it was on the 205 Andy and the same applied for getting you home!!!