Need help with long crank to start after driving and parking

[andrewwynn]

If your pump is original at 160k miles you are on borrowed time. Ours both failed at 133 ± 2. They are supposed to last 5000-6000 hours so 160000/6000=26.667 mph average.

The check valve is in the pump but the FPR on the filter also acts as a check valve so either failing will affect startup pressure.

You need to test pressure with a gauge on the rail. You can use an old school tire gauge but consider it disposable it will ruin the seals inside.

It should hold 30psi overnight. Also should be no wavering of psi at idle.

The FPR will obsfucate a weak pump for months or years. It's a lot of work to get pump outlet pressure at WOT so as pump slowly fails and output drops from ≈ 65 to 50 psi and the FPR hides the slow drop in psi over time.

When FPR or pump check valve fails, the hard start odds the main symptom

Hard/long crank is also a symptom of failing starter as they fail they take far more current but it should also crank slower.

Did I miss of you have i6 or v8?

[getty150]

[andrewwynn]

Get a reading of the current draw when starting. You can measure peak vintage difference from the B+ under hood and your cig lighter port too get a good idea.

On my old e53 you'd multiply the vintage drop by 300 to get starring current eg 0.75v* 300 = 225A. You need a meter that reads peak or you can use a clamp ammeter.

You can change powered pump when tank is 3/4 full no issue. The siphon side you need to get your hands in a ways to deal with connections so 1/2 full or less is better but you do not need to drain the tank. Study up with the two threads I made for the details of fuel supply on the e53 there is literally no better source even bmw tis and repair manual is not as complete or accurate (they copied information from 5 series and is not accurate).

My write up on the Siphon jet details a design defect that allows the siphon jet to self destruct usually about 12-15 years mark. It will happen to 100% eventually and it's a 60¢ repair where any shop will replace the entire Siphon jet usually $500-900 parts and labor!

[getty150]

Originally Posted by andrewwynn

My write up on the Siphon jet details a design defect that allows the siphon jet to self destruct usually about 12-15 years mark. It will happen to 100% eventually and it's a 60¢ repair where any shop will replace the entire Siphon jet usually $500-900 parts and labor!

What!!? Tell me more. Where is your write up?

[andrewwynn]

AWR-fix: e53 Fuel pump / siphon pump details
https://r.tapatalk.com/shareLink/top...ink_source=app


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[plasstik]

After a long search, then even longer break from trying to find out what the issue was.. I finally found out what was causing the shudder/ stutter after re-fueling and after the engine gets to operating temperature.


The Fuel Tank Breather Valve was bad.



After ripping it apart to see how it worked and possible issue, the plunger (or whatever you want to call it) was stuck and not re-tracking.

[plasstik]

Testing to see if your EVAP valve/ Fuel Tank Breather valve is bad or working.

https://youtu.be/xw9NKLTqKUA?si=FfJHq7zcNCWt0UDX

[getty150]

Well good... you're very much like me...your problem/situation and the fact that you take your time in researching the problem. I did replace the fuel filter maybe a couple of mos ago... https://r.tapatalk.com/shareLink/top...ink_source=app
(broke the brittle fuel level line in the process) that was a scare! Been monitoring the results since and last week I concluded that maybe it's the pump itself...I get the slow crank only once out of 8 cranks. Most times it (the crank) almost instantly...just the turn of the key and bam! I did buy a check valve (50s med recommendation) but haven't installed it yet (valve sits in the glove compartment).
I have the valve you say is our solution it's buried in my parts box. Thought I installed it mos ago for the hell of it can't remember.

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