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2012 Mini Cooper Base losing fuel pressure overnight
I finally got my cooper running after 2 years and have a new fuel pump and fuel filter and filter assembly (which has the built in pressure regulator and new hoses going to the fuel pump). It runs at about 72 psi of fuel pressure (non-turbo N-16 engine) which I understand is normal, but it runs a little rough on start up and pressure overnight drops to about 25 psi (I understand that pressure should maintained when off). In looking online, if I understand correctly it is either the pressure regulator which is on the fuel filter housing and is new, the check valve, which is on the fuel pump and is new, or a leak somewhere. I do not smell any fuel leaks. I am thinking a leaky injector, but before I replace injectors, does anyone have any other thoughts on this. I also have a code 2B5C Mass Air Flow, Implausibility, but from a few posts online it sounds like that is due to a dirty throttle body (which I am going to clean along with the mass air flow sensor). Any thoughts on this would be greatly appreciated!
Dropping overnight to 25psi I wouldn't consider an issue.as long as the pressure builds quickly at key on. Never done a fuel filter on one but if it is the type of in-tank filter I think it is minor leaks between the two parts of the filter case are to be expected.
With the MAF it is less than ideal to depend on codes without looking at live data. An implausibility code could mean anything from a a vacuum leak letting "pirate" air or a dirty sensor or a completely foobarred or even an aftermarket free flow airfilter
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Last edit: 3 years 10 months ago by Andy.MacFadyen.
The following user(s) said Thank You: juergen.scholl
I agree with Andy on the pressure drop not being an issue while pressure built up is quick enough to ensure normal engine start.
You could put your pressure gauge just before the injector rail and choke the supply line. If the pressure still drops it's on the injector side, if it holds it would be backwards to the regulator or check valve.
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