Technical Odd problem - fuel pressure?

[Yeti]

My Multipla TD has a very odd problem. It's had it as long as I've had it - I haven't really used it yet!

When trying to start, it won't. Turn it as long as you like, until you give it some Easy Start, it just WILL not go.

When turning over by itself, the fuel pressure is reading BELOW what is 'requested' - this would be causing the injectors to not fire at all.

Once running, the car runs fine, and the fuel pressure reads normal!

I have changed lift pump, fuel filter, injection pump, fuel pressure regulator and the fuel pressure sensor - and not one has made any difference at all.

So, any suggestions? Has anyone seen this problem before? I can't keep using Easy Start to get it going every time!

Thanks.

 

[momoe]

Not heard of this before, given what you've changed the injectors need to be eliminated.
I believe that the ECU won't fire the injectors unless the fuel pressure reaches a given figure, Easystart probably works because the engine catches and runs on the Easystart, the higher rpm then creates high enough pressure.

Any possibiliy that the fuel could have been contaminated? You really need to get a leakback test done on the injectors, Bosch have specialist injection centres which should be able to sort this out.

 

[Zundapp]

Not a good thing to regularly use easy-start on an engine.

Continual use can lead to the break-up of the top piston rings, which then makes the engine even more difficult to start.

 

[Yeti]

I know easy start is bad for it - hence why I haven't been using the car!

The intention is to take the car to Bulgaria and leave it at my house there - but I need to fix this first (along with the broken fuel tank strap, and the broken front spring and the 2 slow punctures it's now got) - preferably before the MOT runs out at the end of next month!

I'm also aware that the ECU will not try to fire the injectors unless the fuel pressure reaches what's expected. I have also drained the fuel and filled it up with fresh diesel.

There is no way I can see that the injectors themselves could cause the fuel rail pressure to be too low while cranking anyway.

There was a known similar problem with Skoda Octavias - they reprogrammed the ECU to fix it.

Still none the wiser here - and still looking for ideas!

Thanks.

 

[Alpitlum]

Check no-one has put one of them tuning boxes on the car, they fit in the loom at the fuel pressure sensor, could be playing up and causing the problem you see here.

Is the engine spinning fast enough when you crank it? how quickly does it fire up with a bump start?

 

[momoe]

Yeti,
try googling injector leak back and you'll get an idea of how a leaking injector might cause your problems - I'm not saying this is the problem just that it might be.
You've already spent a good deal of time and money changing items that haven't made any difference to the problem, whilst this has 99% eliminated these components it has also left you with very little else that could be causing the problem.
You may have a point about the ECU, a faulty ECU could also cause this problem but I doubt if this is a fault requiring ECU re-programming, not seen any JTD engine problems on any forum that were resolved by ECU re-programming.

 

[Yeti]

There's nothing fitted at the fuel pressure sensor loom that I have spotted - I'll have another look later.

It's certainly cranking fast enough - it WILL NOT bump start, no matter how fast it's going. IF you stall it, it's a case of stop, open bonnet, spray easy start, then re-start!

Maybe I'll try the injectors - just need to find/borrow another set! Do they need coded?

 

[Yeti]

Oh, I re-checked yesterday while I was changning the broken spring and corrodded fuel tank strap.

The fuel pressure when cranking is around 60 bar. The requested pressure at cranking/idle is around 350 bar.

Once the engine is started with a puff of easy start, the fuel pressure is around 300ish bar, and the car will run fine all day.

 

[momoe]

Set of JTD injectors on Ebay (250886126524). You'll need to check codes, I believe a code for Multi's is 0445110068 but there may be more than one option depending on engine management system.

Just a thought, is there any way of blanking the injector feed(s) to see if the the pressure rises, this would prove out the injectors are faulty without the outlay of injectors.
The pump would provide pressure up to the max. and then should shunt excess back to tank?

 

[Yeti]

The code on those injectors is 0445110019.

Mine are 0445110002.

 

[Yeti]

Well, I tested the leak off yesterday, Injector no 2 is leaking twice as much as 1 and 4, and 3 is leaking off around 50% more than 1 and 4.

Can't be good.

 

[Yeti]

Well, I bought another Multipla JTD.

Advertised as a burst sump, but what she didn't let on was it was burst from the INSIDE.

So I pulled the injectors out of it and stuck them in my first one - and problem sorted!

Just need to put another engine in the second one now!

 

[martyc5674]

Yeti
What engine is in the one you bought??
Interested in selling me a part off it if it's either a 110 or 115?
Marty.

 

[Yeti]

Depends what you want. It is a 115. I have bought another engine for it, and if the part you want is surplus once I fit the new engine, of course you can have it (as long as it's not the injection pump!)