n52 long crank, no codes. FPR, fuel pump?

taymar · 03-09-2018, 06:41 AM

Hey all,

my N52 is having a long crank from cold issue. The starter spins the engine over quickly, but it can take up to 8 seconds before it fires. Once running, it seems fine. Starts back up fine if it's been sitting less than 30 minutes or so.

I get no fault codes, and charged the battery as a first step.

Seems like a fuelling issue - I've got a new filter & pressure regulator to install, but wondering if the pump is a while you're in there type deal.

Anything else I should be looking at?

thank you

Barrique_Red · 05:15 PM

Hello!

we have similar issues with our 325xi E90, and I am wondering if you have made any progress on this issue?

Ours was taking long cranks to start a couple winters ago, then it was not a problem over the summer, then the next winter it acted up again, and now, in late spring/early summer it is much more common for us to get a long crank on startup.

I am curious as to any information you can provide.

thanks!
mikey.

2006, 325xi, E90, N52, Sedan, 2nd owner, 138000 miles

Barrique_Red · 05-31-2018, 07:47 AM

We attached a fuel pressure gauge and see that the pressure drops as soon as we shut off the engine. There are two pieces in the fuel tank and I do no know if the pressure drop points to one, or both, of them.

Does anyone read these posts regularly?

thanks again,
mikey

Barrique_Red · 05-31-2018, 08:17 AM

I have the same question you did, do I replace both parts in the fuel tank, or only one?

Barrique_Red · 06-26-2018, 04:41 PM

Today we replaced our fuel pump and the pressure regulator, both pieces in the fuel tank. We did this because the symptom (fuel pressure dropping after engine shut off) pointed to the regulator, and since we were in there we replaced the pump too.

Prior to the replacement, the fuel pressure dropped to 20psi or so immediately after engine shut off.

After replacing the parts, the fuel pressure stays above 65psi for 20 mins after we shut off the engine.

Recently, the outside temperature has been quite warm, and the long cranks were not happening, so we will have to wait until the autumn/winter to see if the long cranks went away, but we did in fact bring the residual pressure in the fuel rail back into compliance with the 20 min spec.

TAJA1969 · 07-06-2018, 10:44 AM

I have a engline light half pictured what could this be the cause. Car is running sluggish?

Barrique_Red · 11-18-2018, 04:32 AM

Yesterday we started the car in below freezing weather. Fired right up. I think we fixed it!

Valmal007 · Valmal007's Garage

I have a 328i coupe with a n52 check and had-bad crankshaft sensor . It takes 5 to 8 Sec to start changed the sensor once on it did the same thing again check engine soon light on do all codes have to be erased before it goes to normal.