TD4 2004 starts fine cold, but very slow to start once running for a w

[ajfarrell]

Can someone please advise on the most likely problem with my TD 4 BMW engine: starts fine once cold but after engine heats up and after a small drive, the engine cranks over for up to a minute before starting. Becoming a nuisance if not dangerous situation given I could be stranded!

I've followed a few threads on similar symptoms but no joy...here's what I've done so far:

1. Replaced fuel filter

2. Replaced air filter in engine air take

3. Cleaned gunk out of ERG valve

4. Replaced CAM shaft position sensor

5. Ran a basic diagnostics, air flow pressure is 100kPa idle 140 driving. No fuel pressure reading available on my diagnostic unit (CReader IV)

6. Removed MAF sensor and emission warning light comes on (along with allot of white smoke), associated code shows on CReader; no change in slow start. Reconnect MAF sensor, code fault stops, smoke stops, still slow start.

7. Looked at high pressure fuel sensor , not green or corroded, looks fine.

8. Went to dealer today, said if could be fuel pump...quoted it needing 140kPa to start engine and 400 at high revs, since I can't measure fuel pressure he quoted me 80 quid to run his diagnostics equipment on it and he'll 'write down' the values! He said the pump may be gone as it had enough pressure to start cold for first time but once running it looses power...not sure bout that since the car runs FINE once started after a warm slow constant crank over rub batter down start.

9. I poured cold water over cam shaft sensor area of engine when hot and it started quick.

10. I've run out of options...is it the pump, or something with the sensors?

Cheers folks, appreciate any insights.

Anthony

[tacr2man]

Have you tried a leak back test on the injectors , as too much leak can adversely affect starting ?

[neonovice]

Have you tried a leak back test on the injectors , as too much leak can adversely affect starting ?

+1

Had this exact problem with a 55 plate. It needed 2 injectors.

[ajfarrell]

Thanks guys, I'm going to run a diag on it to make sure it's the fuel pressure leak problem, anybody know if the Delphi PC kit is able to read fuel pressure on the freelander?

Noted today by pouring cold water over the temperature sensor it started, so may well be a lazy sensor either?

[LiamC]

Almost certainly an injector or two. A simple leak back test will confirm this.

[FridgeFreezer]

Could be crank sensor, they like to get weak when hot, when the engine's turning slowest is when the signal is weakest.

[ajfarrell]

Thanks fridge, I thought it was the cam sensor as with the older one when cooled it in freezer it worked fine; relaxed it and no joy.

Will diagnostics pick up the crank shaft sensor fault?

The low pressure pump may also be the problem, may be more prudent to replace first...both cost around the same!

[FridgeFreezer]

Will diagnostics pick up the crank shaft sensor fault?

Maybe, it'll show zero or very low RPM when cranking as the sensor misses pulses. I'd hold off replacing the fuel pump until you can prove a bit more.