E46 330i hot start issue

[agent75 37]

My '01 330i is having hot start issues. I have not experienced it but the missus has described it to me. Has to crank for more than 5 sec before starting after warm and sitting for a wee bit. Sounds like fuel vaporisation but open to suggestions. I will put a pressure tester on fuel rail but just thought I'd ask here first. Never stutters while driving, excellent power, still lovely to drive, oil and water always good. Is there something that keeps pressure in fuel rail that may have "fuct out" and could cause  vapourisation. Poss injector leaking too?? Fly by wire so pressing accelerator when starting will achieve nothing right?? All input appreciated. Shane 

[emandru 17]

sounds like potentially a leaky injector(s).  When you shut the car off the fuel line and rail remain pressurized until next start, but if you have a leaky injector, the injector will drip fuel into cylinder essentially flooding it causing the harder start scenario you're describing. If you wait long enough (ie. cold start) the fuel that would have dripped into the cylinder would have evaporated and this starting like normal. To troubleshoot, you can remove the fuel rail from the engine with the injectors attached and still connected to the fuel line.  Turn the ignition switch on but do not start the car and place paper towel under the fuel injectors.  This will pressurize the fuel line and rail.  If you have a leaky injector, you'll be able to see which one is leaking.  Could always be something else but this is what i suspect.

[agent75 37]

22 hours ago, emandru said:

sounds like potentially a leaky injector(s).  When you shut the car off the fuel line and rail remain pressurized until next start, but if you have a leaky injector, the injector will drip fuel into cylinder essentially flooding it causing the harder start scenario you're describing. If you wait long enough (ie. cold start) the fuel that would have dripped into the cylinder would have evaporated and this starting like normal. To troubleshoot, you can remove the fuel rail from the engine with the injectors attached and still connected to the fuel line.  Turn the ignition switch on but do not start the car and place paper towel under the fuel injectors.  This will pressurize the fuel line and rail.  If you have a leaky injector, you'll be able to see which one is leaking.  Could always be something else but this is what i suspect.

Very Much appreciated. I shall do some  testing and keep you informed

[agent75 37]

On 11/2/2017 at 9:23 PM, emandru said:

sounds like potentially a leaky injector(s).  When you shut the car off the fuel line and rail remain pressurized until next start, but if you have a leaky injector, the injector will drip fuel into cylinder essentially flooding it causing the harder start scenario you're describing. If you wait long enough (ie. cold start) the fuel that would have dripped into the cylinder would have evaporated and this starting like normal. To troubleshoot, you can remove the fuel rail from the engine with the injectors attached and still connected to the fuel line.  Turn the ignition switch on but do not start the car and place paper towel under the fuel injectors.  This will pressurize the fuel line and rail.  If you have a leaky injector, you'll be able to see which one is leaking.  Could always be something else but this is what i suspect.

I did this test tonight and couldn't see any leaking. I will try again tomorrow as too dark now. It is definitely losing pressure as far as I can see as I used pressure gauge and ten minutes later almost no pressure. My only other option may be the pressure regulator but that won't flood the car soo wouldn't cause issue unless fuel is vaporising more easily due to lower pressure in rail??? Hmmmm  

[emandru 17]

hmmm youre right, a faulty pressure regulator wouldn't causing any flooding and would likely cause a rough idle afterwards also.  I presume it idles fine after it starts up?

[Olaf 3321]

Fuel pump relay, or fuel pump.  assuming your filter is good.  that'd me my $0.02.

 

I started with filter, then did relay.  Still had intermittant hot start issue.  AA man tapped tank - started.  Replaced fuel pump, no issues since.

[agent75 37]

Re checked and found one injector leaking - only a little but engine was cold etc so may leak more when warm. I replaced injector with spare so will see how that goes over the next week. Thanks for the input gents 

44 minutes ago, Olaf said:

Fuel pump relay, or fuel pump.  assuming your filter is good.  that'd me my $0.02.

 

I started with filter, then did relay.  Still had intermittant hot start issue.  AA man tapped tank - started.  Replaced fuel pump, no issues since.

I think the filter and regulator are combined on my car... will see how new injector goes

1 hour ago, emandru said:

hmmm youre right, a faulty pressure regulator wouldn't causing any flooding and would likely cause a rough idle afterwards also.  I presume it idles fine after it starts up?

Idles beautifully  

[agent75 37]

Well, I experienced the hot start issue for the first time after my missus noticed it. As I have checked and replaced suspect injectors I am now turning my mind to cam / crank position sensors. I have some off the old engine so will try them. Firstly, does anyone have a code reader I could borrow for beers? I guess there may be some faults in there to avoid chasing my tail on this. Shane 

[agent75 37]

Well, some great news which may be of benefit to others in my position.

 

After some googling I decided it was crank or cam sensors.  My work mate ended up having a reader so I plugged it in and ... boom! it was having an "intermittent intake cam sensor malfunction".  replaced with one off the original engine and it went faultlessly like a cut cat.  very happy and far less scared of electronic gubbins now.  so google was right.  I will post here if the problem persists but otherwise consider it solved!