Stalling BMW
Vehicle runs great ten or more miles. Starts surging, loss of power, restarts a few times, limps along a bit, stalls again, then just cranks. No dtc set, but after sitting a bit, fires right up, runs great. Cleaned throttle body, customer has replaced MAF twice he said for same issue, but only lasts a few months, or whatever. Had lean bank 1&2 dtc's when originally towed in, short term fluctuates at like -1.6, -3.1 at idle now, will go positive when excess air introduced. Gave it a lobotomy ( touched battery cables together), gonna drive again, see what's up. When it acted up on me, stalled and towed back to shop ( fired right up at that point) and I checked for DTC's… none present. Not much info provided for these cars. Feels like when a fuel pump is going bad, but I've not had it in the shop when a no start, just on the road once.. makes it hard to check for fuel. My first post here, any help is appreciated! Thanks.
Before I got to where you said fuel pump. I was thinking it’s a fuel pump
yeah, the more I think of it, I'm gonna hook up a gauge and run it. Excess static from service writer and customer kinda pulling initial thoughts away..
My gut says it’s a fuel pump. Replaced tons of these pumps over the years and they fail in a few different ways, I’ve experienced what you’re describing.
I would most definitely have a fuel pressure gage on it and drive or let it run in the lot for a while and see what you get.
A waveform of fuel pump current extracted with an amp clamp may quickly confirm a bum pump
Is this vehicle a Direct Injected BMW? We've seen multiple issues like this where one of the High Pressure Fuel Pumps Fails. You're supposed to check the fuel rail pressure build up on Crank/Start and compare with the target fuel pressure. This is really common on the N63 Direct Injected Engine where it has 2 High Pressure Pumps.
My apologies, I just saw the vehicle type in the post. Sounds like a Fuel Pump issue. Maybe try to look at the fuel pressure at the rail and see if it is within spec
Fuel tank may not be venting. Maybe wrong gas cap or odd fuel tank repairs gone wrong.
There is a fuel pump control module behind the rear seat back on the passenger side. i have seen many times where the module cuts out when it warms up. You can test power and ground in and out to the pump from the module and determine wich one is failing.
find what's missing when it dies . forget the scan tool (for now) and start with the BASICS ! what's missing ? fuel , spark , injection . go from there . don't over think the problem , and again , START WITH THE BASICS ! as it's heat related , there's a big clue right there .
the “check fuel pump/pressure” responses seem correct, but make sure it’s not a restricted exhaust. Sometimes that will give similar symptoms