306 HDI wont start

[Deanxm]

Hi all im hoping someone can assist, my friend has picked up a 306 estate very early HDI 90bhp i think as there is no intercooler????
Anyway it will crank for ages and ages without starting, the timing is good and the lift pump is working, today he picked up some noid lights and stuck them on the injector plugs and while cranking the engine they do not light up so there is no signal to any injector.

If a squirt of easystart is used it would run on that and then run roughly for a while before stalling.

After several tests he decided to swap injector plugs 1 and 4, he had to extend the loom but now with easy start assistance it will start and tick over/rev/drive fine, if its turned off and started again straight away it just goes after a lot of cranking, if its turned off and left for a few seconds it will not restart.

Just to be clear, there is no signal to the injectors, but if you spray i tiny bit of easy start into the airbox and then turn it over it will fire up instantly and the signal to the injectors apears and it will run fine

He thinks its not getting enough pressure on the rail while cranking, i dont, it seems electrical to me but then there is no EM light on at all.

D

[RichardW]

It won't fire the injectors till it can see 120 bar on the rail, sounds like you are not getting that on cranking (or at least the ECU is not seeing it!), but once the speed comes up a bit the ECU is seeing it and keeps it running. If you had a Lexia you could check.... without, then worth checking the fuel pressure regulator on the end of the IP - DickieG fixed a Picasso by cleaning this. If this checks out OK, then a leak off test on the injectors may be worth a go - a seriously leaking injector can rob the rail of pressure and prevent starting. After that you really need to get it on a diag machine that can read live data.....

[Deanxm]

will a citroen lexia work on a pug? i am actualy going to borrow a lexia clone soon, would that work on the pug?

My friend has a reader and it does give live data to a point but no rail pressure.

The pressure regulator is on the pump and has been substituted for a known good unit.

D

[spider]

It 'might' work if the plug is the same. I think some come with something suitable anyway.

There is no intercooler on any 306 HDi btw. No real room for it

On other models I think only the 110's have an intercooler, certainly that's the case with the 406's.

[Deanxm]

Ive just talked to him on the phone and he is sure the pump could be at fault, looks like a pressure issue anyway and after substituting both the rail pressure sensor and the regulator he has come to the conclusion the pump could be faulty.

I know it didnt drive that well and surged a lot which sounds like air in the system to me but then it died completely and hadnt run in months untill he swapped injector plugs 1 and 4 and then assisted with some liquide cocaine.

What makes it more difficult is it was bought as a none runner just to see if it could be got running, drove it home surging and coughing, got it onto the drive and it would barely start, then after a while it wouldnt start at all, untill now.

D

[Oldpug]

I bet its the pump in the tank?common fault on these HDi`s

[Deanxm]

checked that, its putting out just over 1 bar at the filter canister and it primes up when the ignition is turned on.

Thanks
D

[DickieG]

You can use a Lexia on a Peugeot, I've done it several times by substituting the model number for the equivalent Citroen so in this instance Xsara.

AFAIK if there is an issue with fuel rail pressure then when the engine is turned off it generally continues to run for a second or two after the key has been turned.

The big thing to look for on early HDi's now that they are 10+ years old is duff electric connections on the fuel rail pressure sensor and the pressure regulator on the end of the pump as mentioned by RichardW.

[Deanxm]

This is why i think its electrical but to be fair my fool proof plug test is to wiggle the hell out of it while someone cranks, this is sure to show which one is duff

When i spoke to him last night the pump was just coming off so i would imagine he has stripped it by now, the main concern which i didnt mention is that the guy who had the car before had it conk out on him and when my friend went to look at it he had pulled the filter out of its housing while it was full of derv, there are concerns that dirt has entered the pump or blocked the gauze inlet filters although i dont see it as it wouldnt work at higher pressure/flow, rather than not getting enough pressure in the rail for the ecu to be happy to fire the injectors while cranking.

Do you know why they run on if rail pressure is low?

Thanks for all the input, any ideas are welcome at this stage gents


D

[DickieG]

there are concerns that dirt has entered the pump or blocked the gauze inlet filters although i dont see it as it wouldnt work at higher pressure/flow, rather than not getting enough pressure in the rail for the ecu to be happy to fire the injectors while cranking.

That makes sense but with HDi's the pressure increases dramatically as the revs rise so another thought could be that the increased pressure forces the fuel through.

Do you know why they run on if rail pressure is low?

TBH I don't know why but they do

[RichardW]

I don't think it's low rail pressure that causes them to run on, rather HIGH rail pressure (or apparently high pressure) - in the same way that it won't fire the injectors till it sees 120 bar on he rail, it won't shut down till the pressure drops below 120 bar again. So if the pressure is high, or the reg is faulty, then it takes a bit longer to reach 'safe' pressure before injection is stopped. Idle pressure on the rail should be 297 bar, rising to 1350 bar at full chat on an early system - 2nd gen were running 1650 bar, and I think the latest ones >2000 bar

[Deanxm]

TBH I don't know why but they do Laughing

Thays good enough for me

Thanks for the info gents, 2000bar , indeed

D

[mickeybo]

The 15 pin control relay on terminal 5 supplies a 12v feed to fuel pressure
control solenoid on hp pump this voltage travels through solenoid coil to a
pulsed earth at ecu pin no 50. these pressure control solenoids regulate
the pressure to the fuel rail. it's a pity you did'nt check this with your noid
light Regards Mickeybo

[cwd]

did you ever fix it and what was wrong as i have the same problem now

[Deanxm]

Yes it was fixed, in the end he put a pressure guage on the pump and all it could muster was 78bar while cranking, he picked up a second hand spare and fitted it then put the pressure guage back on and it blew the guage out .

Now runs sweet as a nut, i think the issue was the little non return valves on each cylinder in the pump were allowing derv to pump back all the time (like having a badly seated valve) so it just wasnt making the pressure needed for the ecu to trigger the injectors on cranking.

D