Fuel Rail Pressure at Cranking Speed

[2HQueues]

Having trouble starting my 2007 ZD30 CRD Y61 GU. At cranking speed I'm getting 40KPA according to my scanner. If I get it started I get 130KPA at idle and WOT full load 610 KPA. Could this be the relief valve?

Edit : Scanner software a bit dodgy as those pressures are real low.

Tried different software and am confident these numbers are correct.

10500 KPA at cranking
34000 KPA at idle
160000 KPA at WOT full load.

My apologies.

[robewott]

mine is 130 psi key on. 1600- cranking, 5000psi @ idle, at 110k/h its 20000+. I've had a similar problem about 60000k ago. they put in a complete rail in for a squillion dollars.
If an injector is leaking, it has similar symptoms. I'd get them checked first.

[Hodge]

Easy way to check the relief valve.

[Rumcajs]

Having trouble starting my 2007 ZD30 CRD Y61 GU. At cranking speed I'm getting 40KPA according to my scanner. If I get it started I get 130KPA at idle and WOT full load 610 KPA. Could this be the relief valve?

Edit : Scanner software a bit dodgy as those pressures are real low.

Tried different software and am confident these numbers are correct.


10500 KPA at cranking
34000 KPA at idle
160000 KPA at WOT full load.
My apologies.

Those are the correct pressures,

at idle 34 MPa or 34,000 kPa
max peak 160 MPa or 160,000 kPa

The 40,130,610 kPa are probably feed pump pressures not the rail pressure.

Regards

[2HQueues]

Thanks Rumcajs

My concern is the low rail pressure at cranking speed. I'm pretty sure the injectors aren't leaking, as it is hard to start when cold and hot. One thing I know for sure, it will only start (hot or cold) with a freshly charged battery that cranks it hard. I'm still hoping it's the fuel pressure relief valve. My bank account is hoping for same :-)

[2HQueues]

Thanks Hodge.

I'll get some time to do that tomorrow. I've crossed a few things of the list today, air in fuel line and injectors (I hope).

[Hodge]

No dramas mate. The relief valve seems to be the cheapest fix/culprit around $260 from eBay, in contrast to price of injectors , pump etc....

[robewott]

If you need an injector, buy it off ebay not from the repair shop. They charged me $800(+$700 labour) for mine & i bought a spare one off feebay a month later for $250......crinamal!!!

[Rumcajs]

If you need an injector, buy it off ebay not from the repair shop. They charged me $800(+$700 labour) for mine & i bought a spare one off feebay a month later for $250......crinamal!!!

Just a point of interest there:

When changing an injector you must enter a new trim code from the injector plate in to ECU memory using Nissan's Consult III interface (unless you have an aftermarket one able to do the same)
Whenever you loosen the high pressure line you must replace it.

....so if you find the whole assembly on E-bay incl Consult III unit let us know how much will all that stuff cost ya.

ZD30_fuel_rail.jpg

Here is another interesting take for you to think about ==>

if fuel rail pressure sensor is faulty the whole rail needs to be replaced, Nissan will not sell you just the pressure sensor, that means every injector line needs to be replaced again......

Remember:"do it right first time"!

Thanks Rumcajs

My concern is the low rail pressure at cranking speed. I'm pretty sure the injectors aren't leaking, as it is hard to start when cold and hot. One thing I know for sure, it will only start (hot or cold) with a freshly charged battery that cranks it hard. I'm still hoping it's the fuel pressure relief valve. My bank account is hoping for same :-)

If that's the case (why the idle speed and WOT pressures are OK?) but for your sake lets hope. ZD30 CrD needs minimum 160 RPM cranking speed to start. I'm wondering if the problem is the starter motor if it "sucks" your batteries that down quick.... I have heard of the cases where faulty starter motor was causing hard to start symptoms. Perhaps checking the cranking speed and the current load during cranking would reveal something.

Regards

[2HQueues]

Thanks Rumcajs.

I've ordered the pressure relief valve from United Fuel Injection. I did think that too BTW, why is idle and WOT pressure OK, but not cranking pressure? UFI did tell me it would either be the PRV or one or more injectors with leak past. From what I understand Nissan will tell you you need to purchase the whole fuel rail, but there are plenty of places that will sell the PRV separately. From what I've read around here, many ZD30 owners replace the valve with a plug, which may also be an option. The pressure sensor is something different again to think about.

The starter theory is interesting, I did check and clean the main earth, but not the starter contacts (yet). It definitely wont start if the battery is even slightly discharged (and therefore the cranking speed lower). If I was to tow start the vehicle and it started easily then I guess that would make the starter motor the prime suspect.

Lucky I have a few spare vehicles around to use. This has really made me wonder whether I should be doing the CSR in this vehicle this year. Damn. I bought a diesel because I thought it would be good for hundreds of thousands of KM's, it's only done 98,000. It's not like I haven't been maintaining it either.

Thanks again Rumcajs.