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Old 05-19-2012, 06:14 PM
FERRARI_JUNK FERRARI_JUNK is offline
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BMW E38 740i M60 4.0 V8 motor,erratic fuel pump pressure HELP PLEASE

Hi,i recently got a good deal on a E38 1995 200,000km BMW 740i and i've started having this annoying issue where the engine sputters (its like it hits the rev limiter) whenever i punch the throttle (even in Neutral),it does it at around 3-4000rpm.
It can be driven as long as i dont punch it.
I tested the fuel pump and i am getting 45psi idle pressure then when i step on it,the pressure goes down a bit and then just jumps randomly to 30 then 50psi,essentially cutting power to the engine.
THIS IS WHAT I DID:
-tested pump relay with my e39s relay
-swapped the MAF from my 540i and still the same
-changed fuel pump this morning,still the same
-tested ground to fuel pump
-tested current to fuel pump for fluctuation and its all good
-fuel filter was removed when i did the pressure test and it still happend so thats not it.
-i have magnaflow catalysts so no problem with air flow
*i dont have a CEL on but it does come on momentarily as the engine cuts off,i did the pedal trick and i get 1215 which is air mass flow but it does the same thing with a different MAF and with the MAF removed.And i dont see how it would affect the fuel pressure.

What could it be guys?What could cause the fuel to cut off like that ?please i need some help to get going again.
http://www.youtube.com/watch?v=ysYiGqvFCoE

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