L322 starting Issues

[G3FES]

Hi All, my 2004 L322 4.4 vogue, with LPG conversion, has developed a weird fault, in that when I start up from cold, the engine keeps cranking, even when I release the key, until the engine eventually starts. This does not occur when the engine is warm ,it starts & runs normally. This problem happened suddenly with no
pre-warning. The car has had a recent major service & I bought it with the LPG conversion fitted 18 mths ago. Please help thank you G.

 

[Saint.V8]

Fuel pump tired??

Idle Control Valve faulty??

 

[G3FES]

Fuel pump tired??

Idle Control Valve faulty??

Hi thanks for your prompt reply, Would either these two possible faults show up using one of the various diagnostic tools available?
Cheers G.

 

[Saint.V8]

Idle Control Valve *may* do, fuel pump won't.....

I had struggled starts and then one day flatly refused to do so....turned out to be the fuel pump....

There is a Schrader valve on the fuel rail, maybe worth testing fuel pressure during cranking.

 

[kooky_guy]

By 'Keep cranking', do you mean the starter continues to turn the engine?
Not sure how any of the suggestions so far would cause that...

 

[Saint.V8]

The M62 has an 'Assisted Start' function...the starter will keep cranking once the key has been released until the engine starts or 30 seconds (I think it is)......this continuous cranking is normal.

 

[G3FES]

The M62 has an 'Assisted Start' function...the starter will keep cranking once the key has been released until the engine starts or 30 seconds (I think it is)......this continuous cranking is normal.

Thanks for that. It solves half of the issue, I will do as you suggest & get the fuel pump tested. thanks again G.

 

[G3FES]

Thanks for that. It solves half of the issue, I will do as you suggest & get the fuel pump tested. thanks again G.

Hi again. I have had a pressure test on the fuel line & it was 2 BAR not 3.5 as was quoted. Does this mean that the fuel pump is on the way out? No faults came up on the diagnostics, compression all good. G.

 

[Saint.V8]

Could mean it is getting tired, and won't help your issue.....fuel pump or pressure faults won't show on Diagnostics!

 

[G3FES]

Hallo, I am considering changing the pump,as a matter of course, as it seems to be a likely culprit. I have seen them, for sale, at reasonable cost and thanks to your excellent post, it seems to be a fairly straightforward job to replace it. Thanks for the info. G.

 

[G3FES]

Hello again, I have fitted a new fuel pump & checked the relay, but the beast is still reluctant to start when cold, but starts normally & pulls like a train on petrol or LPG when the engine is warm. Just prior to fitting the new pump, the engine warning light appeared on the dash display, after changing the pump this went out & hasn't reappeared.
Any ideas ?? Please. G.

 

[Zigzagsky]

Worth putting a diagnostic on the car and pulling the code. Even though the light has gone out, the fault code will still be logged.

 

[G3FES]

Hi, Yes That was done & it came up with a code that refers to sensors that monitor co2 emissions. These three sensors were tested & found to be within their operating values, at least, that's what the garage told me. They did find some vacuum pipes that were split & these were replaced, but the poor starting problem persists. However I did notice that the new fuel pump, fitted recently, appears to be running continuously, even when running on LPG. Is there a pressure switch or sensor fitted that shuts the pump down when the pressure is up?. Any advice would be greatly appreciated, cheers G.

 

[Saint.V8]

Pump will continue to run when on LPG...the fuel rail is fitted with a return line fitted to a pressure regulator...so no need to worry about any over pressure.

 

[G3FES]

Pump will continue to run when on LPG...the fuel rail is fitted with a return line fitted to a pressure regulator...so no need to worry about any over pressure.

Thanks for that, you're a star ( as well as a saint ) cheers G.