Help: intermittent starting issues (every 2-3 weeks). 50-60 psi @ fuel rail. HPFP?

[pancakes]

So every once in a while my car won't start. It'll just try to turn over continuously. This will happen no matter how many times I try, but if I let the car sit for a while (sometimes an hour, sometimes several hours), it'll turn over right away and start as if there was never a problem. no CELs (except for an unrelated p0491 for the PZEV air pump).

I hooked my phone app up and it normally measures a normal 600 psi @ fuel rail when the issue isn't happening, but when it's experiencing this issue, it only shows 50-60 psi.

I've taken it to the mechanic, but the car never acts up while it's there so they can't replicate the problem.

Any reason to believe this isn't the HPFP? Does it make sense that it would be an intermittent problem with the HPFP?

Thanks in advance.

 

[GeorgiaBII]

Replace the low pressure fuel pump.

Had the same issue when I got my car. I would stop for dinner come out and the car would fire and die... fuel pressure would be low around 50psi. Let it sit for an hour and it would run great for a week

 

[pancakes]

Replace the low pressure fuel pump.

Had the same issue when I got my car. I would stop for dinner come out and the car would fire and die... fuel pressure would be low around 50psi. Let it sit for an hour and it would run great for a week

But doesn't the 50psi suggest that the LPFP is working?

 

[GeorgiaBII]

That is what I thought as well. But it's residual pressure driven by engine heat. What cured my car was the low pressure pump. Easy to change just pop the back seat bottom up and it's right there.

 

[gdub09]

But doesn't the 50psi suggest that the LPFP is working?

Yes, 50psi is about 4bar which is correct for fuel pressure. Its probably just a bad pump.