BMW stalls after refueling
The engine will start and idle erratically. Once the engine starts, RPM must be held above 1500 to keep running. When attempted to move, the engine will hesitate and bog, then will “catch” and accelerate normally. For the first few minutes of driving, you have to “feather” the throttle to keep it from stalling. After a minute or two, the engine runs normally. The problem does not show up again until the next time I refuel. I tried to capture scan data when the problem occurs, but it is too intermittent. When it’s running good (99 percent of the time) all scan data is normal and no codes are stored. I have driven as far as 300 miles with no problem.
When the problem first occurred about a year and a half ago, it was not as intermittent and was happening almost every time I drove the car. I checked for codes and found P0101 MAF sensor. I inspected all of the intake tubes and found a small crack in one. I replaced all of the intake tubing. The code was cleared and did not return. The vehicle ran perfectly but after several weeks the problem showed up again. I decided to replace all of the vacuum hoses and the (original) intake manifold gasket. Again, the car ran great and I had no issues for several weeks, then it happened again right after refueling. I scoped the fuel pump and it looked somewhat erratic so I replaced the pump with an OEM. I don’t drive the car much so I only refuel about every three or four weeks. The problem has only happened immediately after refueling. I continue to use the car sparingly and for 99 percent of the time, it runs great. Idles smooth and accelerates and drives normally.
I have checked all electrical connections at the ECM and all sensors. I also checked for loose connections at the fuel pump relay. I have done tap testing and wiggle testing on every component and connector I can think of including the electronic throttle actuator, MAF sensor, and VANOS connectors with no changes.
This problem has me stumped. Any ideas would be appreciated.
Anytime I have a hard / no start condition directly after refueling I go to the EVAP purge solenoid and check that it isn't stuck open.
Have you looked into the evap system?
Purge valve sticking open maybe? Catching scan data while it happens would be big.
This sounds like the classic purge solenoid
+1 for purge valve. Not real common but would definitely match the symptom. Its also an inexpensive part that is easy to access.
+1 Here in the Evap Purge Solenoid. Do a small test. Before refueling, plug the hose at the solenoid. refuel. drive. If problem stops, you know where to look.
If the purge solenoid checks out good, after the next refuel have a scope hooked up when you next start the vehicle to the fuel pump fuse and watch the pattern, I have seen worn fuel pumps brush spring contract due to cool fuel causing no starts and or weak pressure until they warm up again.
This has purge valve failure written all over it,see if you can catch the fuel trims going negative while the event happens.
Everyone has mentioned the purge valve. But something off the wall I have seen was a hose inside the fuel tank that was off. This hose was part of the EVAP system and anytime the purge valve tried to work with fuel tank around half or more sucked in fuel in. obviously, the fuel trims went rich when this happened and the charcoal canister was full of fuel. But I would start by checking the purge…