Fuel Presure Fault

[mspdan]

Hi guys,

after some advice really with my y reg hdi as its still playing up and slowly getting worse..

its has some crap fuel in it naming no names *cough*

this led it too keep cutting out with anymore than quarter throttle or bends..

anyway replaced the following (trying keep it simple):

fuel pressure regulator
rail pressure sensor
lift pump
fuel filter
drained tank and started fresh

the car ran fine but it started playing up again and progressivley got worse, to the point where i want to scrap it or buy an xud :/

anyway couple questions and theories if someone could help:

the rail sensor i just tightened up after change, does it need sealing?? (could air be getting in causing a drop in pressure)
the hp pump is slowly breaking up (car is on 111k)
dodgy injectors (would this cause same fault code)

before i get loads of people say change the lift pump i can 110% say it is not, we have tried four different ones, one being a walbro one out of the moonstone and also one that was only a couple of months old. they all came from cars that didnt cut out so have ruled this out..

any help would be appretiated

thanks

[Slam Wagon]

Youve changed the pump but what about the electrics, they all good?

[Poodle]

Definitely worth checking over your electricals before going any further, it starts to get expensive at this point.

Tbh it was always more than likely that the hp pump was going to be below par, the crap fuel will have damaged seals, not provided proper lubrication, etc. I'd suggest replacing the HP pump, as it's so rarely injectors causing this sort of issue. Perhaps leak-off test the injectors first, just to have an idea of how good/bad they are.

I seem to remember you're planning on tuning so the chances are you would have had to do this anyway, i've been there and it's painful but the end result is well worth it imo. If you end up having to go there you may as well upgrade with an R70 too tbh, the cost of a refurb r70 unit is very similar to the cost of a stock refurb.

[pro_steve]

I would clean the fuel pressure regulator again, if you've used crap fuel you'll hav3e dirt in the system and the regulator will get problems frequently. Make sure the seals are good too.

I would also recommend running an injector leak off test. Bad fuel will wreck the injectors very quickly. If the leak off values are all different then it would indicate you need a new set of injectors too.

Try this and update us and we can advise further.

[mspdan]

Youve changed the pump but what about the electrics, they all good?

the electrics are fine i have checked them with a multimeter buddy

Definitely worth checking over your electricals before going any further, it starts to get expensive at this point.

Tbh it was always more than likely that the hp pump was going to be below par, the crap fuel will have damaged seals, not provided proper lubrication, etc. I'd suggest replacing the HP pump, as it's so rarely injectors causing this sort of issue. Perhaps leak-off test the injectors first, just to have an idea of how good/bad they are.

I seem to remember you're planning on tuning so the chances are you would have had to do this anyway, i've been there and it's painful but the end result is well worth it imo. If you end up having to go there you may as well upgrade with an R70 too tbh, the cost of a refurb r70 unit is very similar to the cost of a stock refurb.

It wont cost alot tbh as i have another 5 sat here (dont ask) so i can pull bits from them if needed, only thing im struggling with is a fpr as i only have one spare..

As to tuning buddy, i will be doing another one as the diablo is know a friends car as theres was written off so there is no plans for stage 2 on it for the near future..

I thought hp pump but wondered if the rail sensor had not sealed properly?

I would clean the fuel pressure regulator again, if you've used crap fuel you'll hav3e dirt in the system and the regulator will get problems frequently. Make sure the seals are good too.

I would also recommend running an injector leak off test. Bad fuel will wreck the injectors very quickly. If the leak off values are all different then it would indicate you need a new set of injectors too.

Try this and update us and we can advise further.

I have tried several different fpr's and had it out again a few days ago, was tempted to get another one if i can find one..

I have done a leak of test a few months ago and the test showed one to be down slightly on all the rest but i suppose it cannot harm to do another one..

However i have got two other things to add which may help:

When the car cuts out its always after a bend (either way), changing speed from lower rpm to higher or sometimes when letting off to slow down. When you try and restart it you cant bump it, i have then tried turning the key back on but the lift pump does not prime it makes no noise. The only way i have found to get it going again is to take the keys out then put them back in and prime the fuel pump twice and it comes straight back to life. hope this helps?

Also it runs better when its cold, the warmer it gets the worse it gets.. I did also notice this morning from cold it wasnt idling 100% it sounded slightly off on an injector to be fair, the revs sounded like they dropped off a bit and the car was hunting, like a misfire if that makes sense?

Think i may do a leak of test on it before i change the pump as i have some injectors spare fromt he engine that slipped the belt.

Any help or input is more than welcome people and thanks for the help so far

DAN

[DeeTurbo]

I'm thinking the supply from the lift pump might be iffy. Is your lift pump healthy and the electrical supply from the brown relay at 12v?

[pro_steve]

Ok, so that information is useful. I know you said you've changed the lift pump but are you sure there's nothing in the tank blocking it up? You could potentially have some bad wiring which is being moved when you go around a corner, but that's not very likely.

If you had different leak off values before and you're now getting bad cold starts I would almost certainly look at the injectors. That's always the first sign that there's a problem when you get a bad dle and white smoke when cold. Also the cutting out under load can be due to bad injectors but this is less common.

[Poodle]

Have you read the fault codes recently?

[mspdan]

I'm thinking the supply from the lift pump might be iffy. Is your lift pump healthy and the electrical supply from the brown relay at 12v?

Yes as above have tried 3 - 4 pumps in it from cars that didnt cut out, its even got a walbro upgrade pump in it currently..

my next port of call tbh was to check to seee if the inertia switch or brown relay is burnt or has a loose connection but when i did check the supply at the lift pump a few weeks ago it was within tolerances.

Ok, so that information is useful. I know you said you've changed the lift pump but are you sure there's nothing in the tank blocking it up? You could potentially have some bad wiring which is being moved when you go around a corner, but that's not very likely.

If you had different leak off values before and you're now getting bad cold starts I would almost certainly look at the injectors. That's always the first sign that there's a problem when you get a bad dle and white smoke when cold. Also the cutting out under load can be due to bad injectors but this is less common.

I have drained the tank and started a fresh thinking it may have been dodgy fuel which did help but it still cuts out...

I thought possibly injectors but i do not get any white smoke and it isnt really down on power, it is slightly but i know my maf was playing up and i have that to change..

Have you read the fault codes recently?

Yes Poodle i have all i get is Fuel Rail Pressure, which i presume is when it looses pressure and the ecu cuts the car out with a jolt which doesnt really help pinpoint the fault..

I am thinking of starting again tbh, with the realy and inertia switch and check wiring readings at the lift pump and also try moving wiring to rule that out..

I may try and get hold of another rail sensor and fpr, althought tempted to take the one of the moonstone which runs fine and do the cambelt and stick that in and see what happens..

If it still doesnt play ball realistically its only the injectors left and failing that it shall have to be scrapped as its been like it far too long and im reluctant to take it anywhere as its a nightmare to live with..

[Poodle]

I'm sure I must have asked before, but are you keeping over quarter of a tank in there?

[mspdan]

I'm sure I must have asked before, but are you keeping over quarter of a tank in there?

least it runs is half a tank mate

[pug306driver]

so after half a tank ( tank half full or less ) it buggers about??

[Poodle]

Definitely not that then lol. It does sound a whole lot like a dodgy lift pump tbh, but like you say it can't be that...

Was hoping maybe itd be a new fault, but clearly not.

[mspdan]

so after half a tank ( tank half full or less ) it buggers about??

doesnt matter how much fuel it has in it does it mate..

Definitely not that then lol. It does sound a whole lot like a dodgy lift pump tbh, but like you say it can't be that...

Was hoping maybe itd be a new fault, but clearly not.

yeah i thought same but the pumps work fine in any other car you put them in so i cant see it being lift pump :/

no, loosing patient and will with it know, only so many things i can replace and times i can fiddle with it, damn hdi's

[Poodle]

I don't suppose the tank > engine bay fuel line or the filter housing could be leaking?

[mspdan]

I don't suppose the tank > engine bay fuel line or the filter housing could be leaking?

have checked for leaking Poodle, no such luck unfortunately

what about the rail sensor theory not being sealed properly, long shot but could that cause same issue?

thanks

[Mattinthehat]

FPR's going for about £35 on eBay right now....

If that helps..??

[Poodle]

It could be that, but i've never seen one not seal properly, with 1350bar of pressure i'd be surprised if it'd even start if it wasn't sealed properly. If it isn't sealed you'll be able to see/feel diesel all over it, it won't take air in as it's a pressurised system.

My thinking is that if it's only a problem with sudden changes, whether it be direction or throttle position, then it's got to be a low-pressure circuit or electrical issue as there's little else that would be affected by cornering. The only option left that makes sense imo considering your description of the fault, is that of an earthing or connection issue. Is there any way you can get it on live data logging? Need to see what's changing at the point of cutting out.