Leaking JTD Multipla injectors. Advice req

[Joey spud]

Ok if the garage were getting a correct pump pressure reading then theres not enough pressure being created by the pump for the rail / accumulator pressure sensor to switch the injectors on.

 

The pressure sensor needs to see around 230 bar at the fuel rail / accumulator before it will start switching the injectors.

 

What is fairly common now days on modern diesel systems that are getting a bit tired is fuel leaking back when the car is left for a few hours,obviously if the pump is empty / unprimed then it cant create any pressure.

The systems with low pressure pumps in the tanks (just the same as petrol motors) that also prime the system when you first start tend to mask any leak back faults.

 

When you give it a good sniff of easy start the h.p pump spins much faster than the starter motor can offer and can usually pull the fuel from the tank and it will fun for the rest of the day. (h.p pumps are great at creating pressure but crap at sucking fuel into its self).

 

I dont know if multipla's have an in tank low pressure pump i guess not.

 

So if the garage reading was true then it looks like you have a leak back problem allowing the fuel to drain back when its left for a while,the fun will be finding the cause.

 

One other thought old diesels need a good strong battery/starter system as if they dont spin quick enough or the volts drop too low they wont go either.

 

What is good with HDI pugs etc is they have in tank pumps and if you look at the filter body while someone switches the ignition you can see the body actually bulge as the system gets primed up.

[Lankytim]

It deffo has an in tank pump and it's working, I cracked open a union on the pipe from the filter to the HP pump with the ignition on and it sprayed everywhere.

[alf892]

Get a pressure test done before it has been spun up on easy start maybe.

 

Maybe the sensor in the rail is reading incorrectly so you need to know whether is actually has no pressure......or just 'thinks' it hasn't ..

 

Maybe also worth trying removing the leak off line from the injectors and drying up the spill.....then having a careful look in the morning and seeing if any extra has appeared which would indicate a leak from HP to LPG.

 

It still seems like the cause is fuel pressure (real or apparent) .....whether via the injector into cylinder or down leak off.

 

Probably more maybes to try!

[twosmoke300]

From what I can see they aren't the coded type . Coded ejaculators usually have a code consisting of letters and numbers on top . Sometimes under the connector tho . Is it a 2.0 jtd?

[Lankytim]

it's a 1.9 JTD, and it won't even start on easy start now! I'm fairly sure now that the injectors do need to be coded, the garage put a diagnostics machine on and it didn't recognise the injectors (injectors not found or something), so he recoded the ECU to recognise them. These are the injectors that are off being tested.

 

I have a spare pressure sensor so it may be worth fitting it, if I can get the old one off!

 

I slackened an injector union off today and turned it over, quite a bit of fuel came out if that means anything.

[cort16]

This reminds me of the hassle I had with my 320d. Modern diesels are pish!

[twosmoke300]

Testify !

[alf892]

Slacking the pipe off while cranking should get lots of high pressure fuel as it common rail......unlike a proper pump where you would pulses of high pressure...bit like a plug lead but you get pulses of fuel instead of lektrick obvs.....

[Lankytim]

Right, I've taken the injectors out AGAIN, blocked off the leak off pipe, stuck some old towels over the engine and cranked it over.

 

Not a sniff of diesel came out of the injector pipes!

 

Maybe the HP pump is shagged afterall.

[Lankytim]

OK, had a call from the injector place. The one was stuck and was shitting fuel out the nozzle constantly, so that confirms the original problem. He's found a "good" injector from the spare four that I gave him, although apparently the injector timings and flow are all over the place.  He recons the spare set are actually better than the set I intend to use, but all the nozzles are fooked. 

 

He wanted to fit new nozzles but I can;t take the £360 odd hit so i'm going to put the injectors back in with one of the good spares and take it from there.

 

He's adamant these injectors don't need to be coded to the car and can be swapped around quite happily, and said "don't listen to whatever anyone else says, only listen to ME!" Which scared me a bit but there you go.

 

When I finish work early enough I'll pick them up and wang them in and guess what? I'm going to splash out on new washers.

 

Oh, and I think I know why it's not running with the donor injectors. One is bent so I recon that's stuck too.

[Lankytim]

Working injectors back in, fuel is getting to them but it's still a non-starter.

 

I actually bit the steering wheel and made muffled screaming noises when it wouldn't start.

[cort16]

Is it getting to that point yet? You know THAT point?

[Lankytim]

Yes, but I'm aware of how much money I've spent on it so far (only about £200 odd but still) so I'm a bit reluctant to rip it to pieces with my bare hands and pack it into a wheelie bin. Not just yet anyway.

 

I have verbally threatened to weigh it in, my neighbours already think I'm a bit weird. Are petrol Multiplas any good?

[cort16]

It's got one more verbal then a written warning before you can weigh it in. You obviously can't sell it as someone would come along , lift the bonnet, twiddle a knob and drive off.

My 320d is now driving around town and when it drives past it's not chip fat I smell it's failure !

[Lankytim]

Do these bags of shit have a stop solenoid on the HP pump? Is it controlled by a fuse?

[twosmoke300]

They either have a suction control valve or a pressure control valve . The suction type throttles the inlet flow to alter rail pressure . There are 2 types , normally open and normally closed. Normally open will make max pressure if you disconnect and Nc will make no pressure.

I assume the pressure control type are the same. Careful if you plan to bypass the control as they will soon go overpressure and blow the safety valve which sometimes dont seat back again. Infact have you checked that that isnt your problem . There should be no fuel coming out of the rail relief valve ever .

[Lankytim]

Which pipe is the rail relief valve? I'll have to have a dig about. I have a spare pump I can study. I could even put it on I suppose.

 

I do know that the leak back pipe absolutley spunks out diesel when it's disconnected from the injectors and the engine is turned over. Nothing comes from the top of the injectors.

 

I'm sure this is going to be something simple.. it always is, but then how many cars get fragged for simple but untraceable faults?

 

The spare pump had a valve on the end of it like this..

 

[Rocket88]

I've got a petrol 1.6...............seems fine to me....................

[twosmoke300]

The pressure relief valve on a bosch system on on the end of the rail usually the opposite end to the pressure sensor ,will have a low pressure pipe attached to it . This should be closed under all conditions apart from extreme rail overpressure (ie faulty control valve )

Like I said earlier they can refuse to seal properly once they have been blown open

[twosmoke300]

http://www.fasttest.co.uk/history_diesel_engine.php

 

about half way down is a reasonable schematic.

[twosmoke300]

Which pipe is the rail relief valve? I'll have to have a dig about. I have a spare pump I can study. I could even put it on I suppose.

 

I do know that the leak back pipe absolutley spunks out diesel when it's disconnected from the injectors and the engine is turned over. Nothing comes from the top of the injectors.

 

I'm sure this is going to be something simple.. it always is, but then how many cars get fragged for simple but untraceable faults?

 

The spare pump had a valve on the end of it like this..

 

Thats the pressure control solenoid on the pump . The relief valve is on the end of the rail itself

[twosmoke300]

Just done a bit of homework on the bosch jtd system and I may have been talking out of my arse . It seems to use another pressure regulating solenoid to control the rail pressure via a low pressure leak off pipe.

[twosmoke300]

http://www.bosch-kraftfahrzeugtechnik.de/media/ubk_europe/db_application/downloads/pdf/antrieb/en_3/01_DS_Sheet_Common_Rail_Systems_CRS2_20110826.pdf

[Lankytim]

This is what my fuel rail looks like, although the pressure sensor is on the end instead of the middle,

 

 

There doesn't seem to be a pressure relief valve that can get stuck open or anything like that. 

[alf892]

So you have fuel at the injectors but it does not fire?

 

And the injectors are tested up as OK?

 

I'd suggest a pressure test at the rail maybe

[twosmoke300]

Make sure you use a gauge rated at at least 1600BAR. Bloody expensive

[Lankytim]

The garage said it was getting 9 bar at the rail, but that was found using a OBD gizmo

[twosmoke300]

Not enough , your gonna need 120 odd at least . Problem with reading live data via the obd port is that it doesnt allow for knackered sensors/ wiring/ ecus.

[Lankytim]

I'm going to take time out to analyse whats gone on. I won't include the crank sensor saga, as that was a bit of a red herring.

 

Lumpy running, swapped injectors, runs mint.

 

Won't start in the morning. Low rail pressure.

 

Injectors tested and one is found to be stuck open, so it's letting all the pressure out of the rail.

 

Good tested injectors fitted, still not running.

 

Whats happened between fitting the stuck injector and fitting the good one?

 

Do these air lock?

[alf892]

The garage said it was getting 9 bar at the rail, but that was found using a OBD gizmo

that why I think it needs an actual gauge test.........I don't know but if the sender 'reports' a low pressure reading the ecu may not tell the injectors to fire.

 

Same result as an actual knackered pump...........

 

Taking time to think seems sensible though...........wot you doing on here???