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P38 fuel issues/will not start


SmasherWebbs

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P38 DT2.5 (BMW engine) 118k

Ran fine yesterday, got in this morning and turned over with nothing not even a fart!

Clear hose after fuel filter had a small air bubble in it!

Cant hear the tank lift pump running and fuse not blown.

How can I prove the pump? Is it worth cutting the cable closer to the pump and connecting to a battery?

And is it worth me dropping the tank (which is 3/4 full) or just cutting access in the rear floor to replace the pump if its dead???

Thanks all

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I'd check it's not the relay by bridging it with a bit of wire then seeing if you can hear the pump and see the fuel move.

Check your spill pipes too, although there'd be a leak.

I'd also suggest if you do need to replace the pump then it won't be the last time you're in there and to aid future diagnostics I'd recommend the 'cutting a hole' approach. The carpet's really thick and makes the 'repair' more or less invisible.

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Right ignition on and 12v at fuse in engine bay I even swapped the fuel system relay with another and still nothing from the tank. Can I assume that the pump dead ?

Next I would like to know where can I find the cable running to the pump?

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In most cases, you'll find it attached to the pump mounting flange on the fuel pump.

:ph34r:

And that would be on the tank that is full and still attached to the bottom of the vehicle. smart arse!

What I would like to know is where the cable runs from between the engine bay fuse box and tank. I'm planning on re running it to a new inline pump.

I could do with a small person to crawl under and find it for me as I'm to round to get all the way under.

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I'm planning on re running it to a new inline pump.

That on it's own'll no dae.

The fact that you have bubbles in the line means the pump has probably failed if the spill pipes are good and no leaks from the injection pump.

You'll be trying to suck fuel through the original pump filter which is probably blocked and sucked itself into the pump and through the valves that are there too. The cutting the hole in the floor isn't a big job.

You bridged the fuel pump relay yet? That's where the other end of the wire is you're looking for to energise the pump

You measure how much fuel comes out in a minute to see if the pump's working or not. I got like 120ml and changed it and no dramas after. The spec was 180ml I think.

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I seem to remember an inertia switch thing too, it cuts power to the pump. It was ages ago I had all this but it's coming back to me. I used a nibbler to cut the hole out the floor as the hoses and wires are right underneath but to be fair a grinder would do fine as long as you don't go daft.

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Checking the inertia switch is easiest. It's in the passenger footwell on a LHD, not sure about RHD.

If that doesn't do it, use the circuits in RAVE to find the wires going to the fuel pump: check for continuity and/or apply 12V directly to the pump to see if it runs or not.

Filip

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'Bodged it' for now and its running with a inline lift pump. :i-m_so_happy:

tried bridging the relay and nothing! pump is dead!!

Looks like im going to invest in a nibbler as I cant trust myself with a grinder when its that close to the tank!

Thanks all! :)

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