Crank but no fire first key turn, starts right up second key turn?

[Cbouts]

Solution here -> https://www.ecstuning.com/b-genuine-...p/16142229684/

[heinzboehmer]

OE BMW, entire assembly.

Ah, I was going to suggest you check (and replace) the submersible convoluted tubing if you had gone aftermarket, but that shouldn't be a problem with a whole new assembly.

[ATB88]

Yeah it's part of the fuel pump. Did you swap it out for a new OE pump or did you go aftermarket?

OE BMW, entire assembly.

[heinzboehmer]

Question about check valve: this is a part of the fuel pump assembly, yes? If I've recently replaced my whole fuel pump assembly, I should be able to rule out the check valve entirely, yes?? Is there a chance that my check valve on my new pump just failed really early??? It would be really nice if this was the answer to my problem.

Yeah it's part of the fuel pump. Did you swap it out for a new OE pump or did you go aftermarket?

[ATB88]

Question about check valve: this is a part of the fuel pump assembly, yes? If I've recently replaced my whole fuel pump assembly, I should be able to rule out the check valve entirely, yes?? Is there a chance that my check valve on my new pump just failed really early??? It would be really nice if this was the answer to my problem.

[sapote]

Yes fuel pump makes sense. I am trying to start it right away like normal. Thanks.

why not try to prime the pump a few times before cranking, just to verify if it's due to fuel pressure from an old weak pump or leaky check valve? It's a good idea to let the pump priming and building up pressure before cranking -- save the starter in the long run.

[sapote]

You can also disconnect the fuel pump fuse and let the engine consume the fuel in the fuel lines.

This method could burn valves due to too lean fuel.

[sapote]

This could also be a symptom of a starter motor going bad

why starter? It cranked ok except that the engine did not fire up?

[eacmen]

Not necessarily. If it's a warm start, the car's expecting there to be pressure in the system already and in my experience hearing the pump prime isn't enough. A bad check valve and/or a leaking PTFE submersible tube are common causes for this issue even when the fuel pump is in good working order.

Agreed. I think the OP is experiencing cold start issues though.


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[ethan]

If this only occurs on warm starts. Then it's your fuel pressure check valve. The fuel pump doesn't always prime on warm starts so if your check valve is bad then all the pressure bleeds off. On cold starts your pump will prime every time (audible).

Can confirm a bad check valve will exhibit this behavior, but I've also found that the factory fuel-safe/submersible tubing between the pump and the housing likes to leak at the junctions allowing pressure to escape. This is particularly common in fuel pump swaps when reusing the original tube. Radium sells new replacements and that has cured the problem for me twice in two separate E46 M3s.

[ethan]

Try turning the ignition to II but don't crank it for a few seconds. If the no-start issue goes away then it's likely fueling related. If it persists then look elsewhere.

Basically if the fuel pump is going out it will take longer to build pressure and cause the no start.


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Not necessarily. If it's a warm start, the car's expecting there to be pressure in the system already and in my experience hearing the pump prime isn't enough. A bad check valve and/or a leaking PTFE submersible tube are common causes for this issue even when the fuel pump is in good working order.

[eacmen]

Yes that’s what happens, if I delay slightly I have no issues. So am convinced it’s the fuel pump. Even if I’m wrong I suspect I would need to replace it anyways with my age/mileage.

I would switch/inspect fuel filter first. Something you should do anyway if it hasn't been done in quite some time.

But I think you're right. likely the pump.


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[Maxhouse97]

Yes that’s what happens, if I delay slightly I have no issues. So am convinced it’s the fuel pump. Even if I’m wrong I suspect I would need to replace it anyways with my age/mileage.

[eacmen]

Back to the fuel pump, glad to hear that it’s a easy swap. Do you think this symptom is a sign that it is wearing out? To me that’s another reason to go replace with new, as I mentioned I have a plan to incrementally do that as issues pop up so I can keep this car running well for a long time. It is also currently my daily, so I’d like to keep it reliable.

Try turning the ignition to II but don't crank it for a few seconds. If the no-start issue goes away then it's likely fueling related. If it persists then look elsewhere.

Basically if the fuel pump is going out it will take longer to build pressure and cause the no start.


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[Maxhouse97]

Back to the fuel pump, glad to hear that it’s a easy swap. Do you think this symptom is a sign that it is wearing out? To me that’s another reason to go replace with new, as I mentioned I have a plan to incrementally do that as issues pop up so I can keep this car running well for a long time. It is also currently my daily, so I’d like to keep it reliable.