HDI running problems

[mark21TD]

Hi all.
I've not been on here for a good while but need some help.

I'm having problems with my daughters 306 HDI (2001) with Bosch fuel system, it started off cutting out and going into limp home mode.
the codes were read and it was showing
P1521 clutch sensor
P1138 fuel pressure regulator
P1121 fuel rail pressure

After some research I changed the high pressure pump, after this it seemed to run fine and would rev to 4k with good power.
However it cut out after a couple of miles, it restarts ok but only if you give the intank pump time to repressurise that part of the system.

I've swapped the fuel pressure regulator but it's still cutting out.

The codes were read at this point and showed po230 (low pressure system), although this was read on a cheap code reader so don't know if it would still show the P11 codes.

I have since changed the pressure sensor in the rail and the fuel pump relay (fuel filter was changed and strainer on the in tank pump checked before anything else was done).

The MIL light is still on (has never gone out) and the engine cutts out after 50 yards, it doesn't matter if it's just been started or been sat ticking over for a few mins first.
Sometimes once restarted it'll drive fine for 1/4 mile (not gone any further just in case) and other time it'll cut out after 2 or 3 hundred yards.

My wifes old 406 2.1td finally gave up a few months ago but we replaced it with a 406 2L HDI 90 with Bosch fuel system so some of the parts that I've swapped have been from this.

Can anyone help please.

[mark21TD]

A mate is lending me his Autel Maxidiag in a few days so I'll be able to read all the codes and veiw live data, hopefully this will help.

[Doggy]

Have you changed the lift pump?

[mark21TD]

Have you changed the lift pump?

Not yet, but a known good one is coming with the code reader.

[mark21TD]

The code reader hasn't been sent yet as his car has died so he needs it right now.

In the mean time I've done a leekoff test and these are the results
No1 45ml
No2 55ml
No3 60ml
No4 50ml
this was while idling for 10 mins
These are fairley accurate but not spot on as my measuring cylinder only reads in 10ml increments (baby's bottle).

From what I've read they should ideally be within 10% of each other, but would this amount really drop the rail pressure that much ?

[Doggy]

I can't be sure, but to me, those numbers don't look too bad. When I tested my last HDi, I got nearly twice as much in one pair of bottles as the other two - that car was still starting & running OK, just very uneven at tickover. It's always possible you have 4 worn injectors, but hardly likely.

As you seem pretty handy with cars, maybe you could rig up a pressure gauge on the filter / LP side of the pump? It should run at something like 4 - 5 bar. You need to establish you still have pressure when the car's misbehaving. (I've never tried this, it's just a suggestion. Obviously, you need to leave the HP side well alone).

[mark21TD]

It's fixed

I pulled the in-tank pump out again and noticed a bit of plastic inside the tank,
on closer inspection it's part of the lift pump housing, it clips in and guides the returning fuel into the center of the housing.
This must have fallen off when I replaced the pump after checking the strainer.

With this clipped back in the car runs fine, no cutting out and no fault codes (once errased).

So the original fault was the HP pump, after changing that the p11 codes didn't come back, but as I'd removed the in-tank pump before changing the HP pump we still had po230 code until now.

Thank you all for your help and advice.

[jonsowman]

Well done! Glad it's running well again

[mark21TD]

Well that didn't last long, it's done about 20 miles and the MIL light came on once started and was in limp home mode.
On the way home it cut out twice.

Codes read, po230 (low pressure system)
it's also showing "intermittent fault. fuel pressure regulation fault. stop requested but requlator (yes it's spelt requlator not regulator) still active"

Any ideas guys ?

[Doggy]

Sorry to sound like a broken record, but it isn't completely clear - has the lift pump been changed?

Still sounds to me that the most likely scenario is intermittent lack of fuel supply to the HP pump.

[mark21TD]

The lift pump has not been changed as yet, it was next on the list.

[jonsowman]

Agree with Doggy, lift pump sounds like it's to blame!

[mark21TD]

Another lift pump is winging it's way to me now (well it'll be posted to me tomorrow anyway).

[mark21TD]

Had another play today.
I've replaced the in-tank lift pump (note the 306 and 307 both use the same pump although the housing is different).
It starts but cuts out a few seconds later.
Code reader (MaxiDiag FR704) said
intermittent fault.
Diesel high pressure monitoring function.
Diesel high pressure regulator jammed.

I changed the high pressure regulator (for a known good one) and reset the the codes.
It's still cutting out and the code reader is showing,
intermittent fault.
Diesel high pressure monitoring function.
Lack of pressure (leak).

Could it be the O rings on the regulator as they're not looking their best ?

Or has anyone else got any ideas ?

[madmadmax]

there is a yellow plug low on the front of the engine thes can some times get water or the harness extension can get damaged in the so give it all a check over

also did aline the marks on the lift pump and tank as not doing so can lead to fuel starvation when accelerating with less than 1/4 than

have you changed the fuel filter?