W210 Fuel System Fault?

[E55BOF]

The car is a '98 E55. The non-starting problem may not be the ignition switch (my other thread in Electronics).

The engine cranks over beautifully, but does not start. A few seconds after I stop cranking it over, there is no residual pressure in the fuel rail. Is this normal? If not, as I suspect is the case, where might I start looking? Please help...

E55BOF

 

[E55BOF]

No fuel pressure at all with the key in the running position.... Not the ignition switch (phew...), it would seem.

Could anyone confirm that the fuel pump relay on the W210 E55 estate is the black one under the rear seat with the battery and the fuses?

E55BOF

 

[guydewdney]

some sort of fuel pressure regulator failed? usually a small cylinder affair on other german cars ive worked on

 

[BlackC55]

It sounds like the fuel pump has had it.

 

[E55BOF]

Thank you for that; I was hoping you'd give your opinion.

I'll be much relieved (and much less poorer, and the car will be fixed much sooner) if the ignition switch is OK. My local indie (VT Wheels) is sending a chap round shortly to read the codes for me, so with luck I'll know the problem soon. If he says it could be either fuel pump or relay, I'll try the relay first as the cheaper option.

There seem to be plenty of pumps on Fleabay, made variously by Delphi, Luca and Meat & Doria eek:; bizarre name in English). Do you have any views on which to buy if necessary?

 

[BlackC55]

If it is the fuel pump or relay you will not get any codes at all.

Buyt a Bosch pump from ECP

 

[E55BOF]

Thank you for that; Bosch it will be if I need a pump. Could I ask, is the fuel pump relay under the rear seat, or OS rear of the engine compartment under the black cover? Damned if I can find it on WIS, and I need to have a finger and ear on it to see if it's making when the ignition is switched on.

As the chap is coming, and I'll have to pay him, I need the codes read anyway; the OSF parking sensors don't work, and I've been meaning to sort it ever since I got the car. Might be something else show up, too, though the car ran fine - until it wouldn't start.


Kind regards

Dennis

 

[BlackC55]

I think its under the rear seat but ccant be sure.

 

[ChrisA]

I think it's in the boot, next to Navi system. Bottom relay but check diagram

 

[E55BOF]

Thank you, but alas! It's an old E55 estate, pre-facelift, so no Navi (and no boot...). I'd check the diagram if I could FIND the b****y thing on WIS, but I can't.

 

[E55BOF]

I think its under the rear seat but ccant be sure.

Fair enough; thank you for the inputs.

 

[BlackC55]

I think it's in the boot, next to Navi system. Bottom relay but check diagram

It's a 210

 

[shirleydrive]

It is K27 relay adjacent to battery under the rear seat. Fuse terminal 30 in rear fuse carrier.
Could also be a problem with K40 relay module in engine compartment.
I,m assuming that E320 fuel set is similar to your car.
Hope this helps, Mike

 

[E55BOF]

Thanks Mike. The V8 E55 is not the same, though; there's only one relay under the rear seat by the battery, the fuses there run from 1 to 20, there is no fuse no. 30 on the car at all if the MB fuse designation sheets are to be believed, and the fuel pump fuse is no. 6. The E320 is a V6, which presumably accounts for the differences, since they're both the same year.

HOWEVER... There is no sound of a fuel pump running when the ignition is switched on; BIG clue! I've checked the relay and the fuse, both of which are fine, and in the morning I'll take a good look at the actual wires to be sure that it does indeed feed power to the fuel pump; it seems like a good bet, though. If my assumption is correct, then a new fuel pump beckons.

Dennis

 

[E55BOF]

Looks as though Olly is right; no surprise there.

When I put a 6/12A battery charger on the pump, correct polarity, whether on low or high rate, the needle goes right up to the top end of the scale (12A). Cranking, there's about 9v appearing at the pump terminals, but still no pressure in the fuel rail. The pump does in fact make a slight sound; that hum you get when an electric motor is trying to turn, but can't. Seized, I reckon. I hope this information helps someone else.

Wish it had waited until the car was parked in my drive, not an airport car park at midnight!

I won't go for a Bosch pump, though; it turns out that WIS lists a Pierburg pump as OE, and that's what is on the car, so I'll go for that.

Happily, ECP have an offer on the Pierburg (OE) pump (£110), so I'm picking one up tomorrow. I don't have a pipe clamping tool as such to prevent the inlet pipe from tank to pump leaking when it's disconnected, but a straight-jaw mole grip wrench, with rubber piping over the jaws to prevent damage to the clamped pipe, has worked well in the past, and I see no reason to think it will not do so now.
Does anyone think it essential to replace the crimped fastening clips on the pressurised outlet pipe with other crimped items, or will stainless Jubilee clips do the job? System datum pressure is only 4 bar; we're not talking diesels here.

E55BOF

 

[E55BOF]

Aaaand... the fuel pump it was. Thank you one and all.

As that's what was fitted OE, I bought a Pierburg pump from ECP, but though the box said "Pierburg", it was made in Poland by TI Automotive. They took over Pierburg in 2003!