Date registered: Apr 2013
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Mercedes Benz W202 near stalling when stopping or accelerator lift
Hi hopefully this is a valid new thread as I cant find any that are a close enough match for my issue.
Car is a 1995 W202 C220 with what I believe is the M111 engine (could be wrong)
Symptoms are simply when I press on the gas and release, the revs drop well below normal and engine nearly stalls but doesn't, also similarly when driving whenever I get to a stop sign or traffic lights and have to stop the same issue occurs the car nearly stalls. No CEL is on.
Checked and tested and disconnected MAF so not the cause as it causes further erratic engine behaviour when not connected
Disconnected Cam position sensor does seem cause further erratic engine behaviour
Another possibly related symptom is the Fuel pump does not shut off while key is on prior to starting, it also sounds like bubbles going through a hose pipe.
My guess and I'm hoping someone can confirm is that either the input pipe to the pump has a leak (no fuel is visibly leaking) and is sucking air through (also in so doing preventing the pump to reach proper pressure for shut off and or idling)
or the pump is worn out causing a lack in pressure (wouldn't explain bubbles though right?)
or clogged Filter (wouldn't explain bubbles or failure to reach pressure and subsequently shutting the pump off)
or faulty pressure regulator valve / sensor (not 100% sure if these cars have them but BMW for eg do and its common enough for them to go bad) if its just a sensor then unsure how that would affect fuel pressure but probably badly if it is stuck at a running pressure instead of idling pressure?
I have been driving the car like this for almost 4 years and behaves fine as long as when I come to a stop I keep the revs up.