Not starting - fuel shut off valve 4 pins and strange voltages

[pcman_jh]

My 1999 E300 diesel failed to start this morning for the 1st time. I noted no fuel in the pipes at all and it didn't appear to be pumping fuel around when cranking which suggests nothing getting pumped or the lines are blocked with the likes of sticking stop valve.

Anyone know why there are 4 pins on teh shut off connector when I'd imagine all it needs it 0 and 12V? Two of the pins (nos 1 and 2 appear to be earths), with 3 coming in at a strange 1.8volts and pin 4 at 5 volts with the ignitiion switched on. Any idea why these strange voltages?

When I put it together again, or plugged it in to be precise, the fuel starting flowing when cranked so it eventually started again.

With all the cranking that's required, it started showing a EPC Engine Electronics warning which now appears every time I switch on the ignition!!

 

[Parrot of Doom]

I'm busy working this week, otherwise I'd pull mine off and measure the voltages for you. Sorry I don't have time right now

Is there any diesel in the connector or socket? If so, get some WD40 and spray it around in there to displace it. I think mine has a slight diesel leak in the connector, but nothing major.

You should also check the fuel lines for leaks, if the pipes are brown/orange its time to replace them. Check the filter o-ring, and also the big fat o-ring on the pre-filter. There is an o-ring on the back of the shutoff valve, its simple to replace, 2 torx bolts hold the valve on the pump, remove the windscreen washer bottle to gain access, use a mirror to help you see the hidden one. Be careful not to lose the o-ring inside the pump!

Oh and if it is a fuel leak rather than the shutoff valve not working, parking the car nose down overnight is sometimes a big help in the morning.