Hard to start after 1-4hrs after shut down

[Doug]

I have a 2005 BMW 325I manual with 120k. it starts right up fine on a cold engine but if it sits for longer than an hour after running I need the crank it for a while to start it. I checked for codes but nothing came up. I’m thinking it may be a bad sensor or leaky injector.

Topic

[hondaguy453]

It sounds like a faulty fuel pressure regulator. If you have a fuel pressure gauge you’ll be able to see if fuel pressure drops after a certain amount of time. Should only drop about 5psi after shutting the vehicle off, but look up specifications for your vehicle to be sure. Your car starts when cold because it is in open loop which means the ecu will want to dump fuel into the engine until it is up to operating temperature. So, when your car sits while still within operating temperature, the fuel pressure drops and takes a while for the fuel pump to bring the pressure back up. This is just a hunch, but I think testing fuel pressure will give you an answer to your problem.

[Doug]

I have replaced the fuel pump and the filter, I believe the regulator is part of the filter? I’ll check for a pressure drop….thanks.

[hondaguy453]

Did you replace the fuel pump because of this? When you have the long crank, try spraying ether in the throttle body. If it sounds like it wants to start, then it’s a fuel related issue. But you’ll for sure be able to tell by doing a pressure test.

[Doug]

I thought it may be a fuel issue so I replaced the pump and filter. I do the pressure test.

[Richard Kirshy]

Fairly easy to check..
Try cycling the key a few time and let the fuel pump build pressure.
The if you get an immediate start you’ll know that the check valve is leaking and your losing fuel system pressure.

[James]

If it was check valve. Why would it start fine on complete cold start and only give problems after being drove and shut off for “awhile”
I may not be reading complaint right.

[James]

Same question in regards to weak fuel pump. Why on cold start is all well.

[Doug]

Thank’s guy’s it ended up being a leaky injector.

[Richard Kirshy]

[quote=”jjohnson1″ post=175065]If it was check valve. Why would it start fine on complete cold start and only give problems after being drove and shut off for “awhile”
I may not be reading complaint right.[/quote]
It’s a beamer …..
I have no specifics on how their fuel delivery loop is set up or if it’s a return-less system.
It may be that the valve only shows faulty at temperature causing a loss in system pressure and when cold operates normally.

[hondaguy453]

Nice, glad you got it figured out!

[hondaguy453]

Even if the fuel pump was weak, the vehicle may still run normally. The ECU would just compensate by just setting the injector pulse width to a longer on time.

[David Essien]

Please, were you able to fix this cars problem?

[Author]

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