C5 X7 no start (or only runs for fraction of a second)

[Peter.N.]

Thanks Gibbo I will (may) remember that. I have never had occasion to buy one, perhaps a second hand original would be better.

Peter

[MattBLancs]

Morning all,

Thanks for the replies. Not sure about the priming bulb but will investigate when slave cylinder replaced.

Think my 306 had an "eBay special" priming bulb and never went wrong - must have landed lucky back then as didn't perish for me.

New slave cylinder ordered last night from Autodoc - "no parts found" on GSF,
out of stock and twice the price at Eurocarparts (£140 Vs £67 from Autodoc) - both Valeo branded (usual unhelpful lack of specifics on Euro's site) so about 2 weeks till that lands.

Just making a start on stripping down to get the box off. This (2009) is about the newest thing I've owned/worked on - nice how stuff routinely "just unscrews"

Matt

[MattBLancs]

Gearbox out, slave cylinder (and input shaft lip seal) changed, gearbox back in and starting the reassembly. Subframe remained in place but the bolt on front alloy crash tubes taken off. Gearbox just and only just comes out with the subframe still in place. Came out ok but almost gave up (on not removing subframe) when getting it back in!

Also changed lower rear engine mount (was starting to separate rubber from alloy centre section. Seemed daft not to swap it for £10 whilst driveshaft out)

Mounting bolts for driveshaft bearing swapped from chewed up torx type cap heads to conventional M8, 13mm hex head bolts. Quarter inch drive 13mm socket and long extension much better for access than 3/8 drive torx bit - minimal clearance with the bulky inner CV joint in close proximity.

Matt

[MattBLancs]

Ok further updates:

Toughbook and Diagbox received, set up and C5 codes read. Will post them up when get chance, but only one that remained is the glow plug one (which won't stop it running)

Finally got chance to try easy-start. Tried initially by disconnecting MAF from air filter housing. Careful not to spray it on the sensor itself. But route to engine appears to long (via turbos, intercooler etc) so no additional running beyond the "normal" start-stop cough.

Reinstated air filter housing and disconnected flex hose on inlet manifold spigot. WD40 spray nozzle between spigot and hose, popped on loose, jubilee left loose.

Few tries with ever increasing squirts, then suddenly engine roared into life with (as pretty much laid over the engine to reach the spray position - frightening the flipping life out of me! My dad sat inside manning the key reckoned 3500rpm or so, me in the engine bay I'd have guessed more life 30000! (slight exaggerated but you get the feel for what it was like from my perspective!) initially burst of loads of revs!
Returned to idle and ran fine for about a minute. Stopped engine for about another minute. Restarted fine.

Stopped again, removed spray nozzle, retightened jubilee, and...


...back to square one. Endless cranking with little start-stop cough.

So current thought is fuel not getting through at cranking speed (but does at forced into life via easy start speed) will investigate fuel filter, priming bulb, etc as next course of action.

Battery back on charge as don't think it is in first flush of youth - lots of cranking does soon begin to sap its power.

Oh and thunder showers / cloud bursts are rather getting in the way of progress!

Matt.

[myglaren]

Is the cranking speed high enough? A frequent problem with earlier C5s but couldn't say with regard to X7s.
I have had to have my starter replaced, as has James (Hellrazor) and possibly others.

Needs to spin quite fast.

[MattBLancs]

Cranks over ok I'd say, especially when battery charged up again.

Will see if I can measure it, have a mechanical tacho somewhere. To me I'd say it's more a case that battery capacity isn't great rather than cranking amps low - speculation on my part, but hope description makes some sense.

Economy Mode Active very soon to switch on (and can soon have to manually close the electronic boot!) So think it's an old battery.


Matt

[myglaren]

That was what I thought but the battery turned out to be OK, starter was just too slow, although it seemed OK until compared with one that was up to spec.

[MattBLancs]

Ok further update:

Current hypothesis is the in tank lift pump isn't performing. Top of tank six pin black connector. Two pins unused. Two small wires assumed to be level sensor, two chunkier wires assumed to be pump feed. 12.24 volts measured when ignition switched on (and continued a good few seconds after switching off)

No noise from pump at all. Thumped bottom of tank in blindly optimistic attempt to jolt in to life, but no change.

Is there access to wiring diagrams to confirm my hypothesis? Looked on Diagbox but seems to be beyond what's available (without connection to PSA servers)

Thanks for help and suggestions so far.

Didn't get turn over speed measured, will see if can try tomorrow when battery topped up once more.

Various spurious faults logged in diagbox but those that list an associated voltage suggest it's nonsense reported during very low battery voltage (e.g 8.3 volts against one fault)

Matt

[MattBLancs]

Grey and yellow/green were where 12 volts detected

Picture tells a thousand words etc

[wheeler]

Are there pins in the tank unit that match up to the thicker wires? I suspect there is no in tank pump on this car (although the wiring can still be present & live), If there is a hand primer there is not normally an in tank pump.

[MattBLancs]

Yes, four pins in the socket (the two absent ones corresponding to the two little green lumps on the wiring socket)

Two chunky cable aligned pins read open circuit (but likely would do so for either a dead pump or no pump!)

Will try and get the plastic ring unfastened tomorrow and see what hides within the tank.

Makes sense that no need for a priming bulb with an in tank lift pump (unfortunately, as hoped I'd found the fault!)

Matt

[MattBLancs]

No in tank pump, but some in tank muck!

What's the collective opinion on the accumulation of muck here?


To confirm, no in tank pump on this model

Under tank cover. Thin wires to level sensor. Other two go nowhere

Matt

[wheeler]

Doesent look great, whats it like inside the tank? Have you had the fuel filter out for a look? not sure if its a sealed unit or a replaceable cartridge on this engine? If its a sealed one i think i would be cutting it open for a look.

[MattBLancs]

Hard to tell what is like inside the tank as is near enough brim full - poor timing! Decanted 5 litres into a can as was trying to spill over when putting the sender/pickup back into place.

Fuel filter recently replaced, is a big plastic unit. New one is Bosch, old was marked MANN - cut that open and inner element was marked Purflux. No massive accumulation of muck in the filter. Not worked out how long the MANN filter had been in place from previous owner's service history.

The muck is same sort of consistency as coffee grounds, surprisingly firm. Not sure why but expected algae to be sort of gelatinous in texture.

Managed to knackered the clips on the plastic lid (not top of tank, but the push on one on the body shell)

Note for future reference, IT DOESN'T JUST PULL OFF. The clips (location discretely marked with arrows on top surface) should be pushed back with some flat tool (thinner than flat screwdriver, must be more akin to a feeler gauge) special tools can't be too wide otherwise won't push clip back far enough. The clips themselves are very flimsy - the one that did survive seems under stress to reach the point it would unclip.

Or put it another way, it seems engineered specifically to break! Will re-engineer something to sort it as short route from this hole to the road below. Quite surprised given the number of plastic covers under an X7!

Next, after a re-priming, manually and quick try again is battery disconnect and starter off. Will strip regressed, clean up commutator and see if goes any faster. Still don't think it is TOO slow, but as it's reasonably accessible it's worth a fiddle with it.

Thanks,

Matt

[MattBLancs]

This was under the plastic gauze, more "coffee grounds"

For future reference: pull the centre but of these upwards, then click into place. Then push down outer. Result is connection is only tediously stubborn to remove rather than impossible or broken