I got an 1987 325is a few months ago with a cold start issue. I have gone through the whole intake side of the engine with new gaskets and hoses. I have done a smoke test to ensure I have no vacuum leaks. The problem still persisted where if the car sat for more than 30 minutes, it would take about 5-10 seconds for it to finally sputter to life. I just replaced the fuel filter, fuel pump, and fuel pressure regulator thinking it had to be one of those. It still won’t start right up. If I prime the fuel pump by jumping the fuel pump relay, it fires right up. What else could it be? When I pulled the gas line between the fuel filter and fuel rail, it sprayed gas everywhere after sitting for a few hours so that line still had pressure. My car has the inline fuel pump and the in-tank transfer pump. Could that pump be the culprit? I am tired of just throwing parts at it. Just as a side note, at idle the car does have a random cylinder misfire and OCCASIONALLY a surging idle but I don’t know if that has anything to do with this issue. Any insight helps. My MPG is poor as well (17-18) driving to and from work about 15 miles everyday, so I plan on replacing ignition components as well as O2 sensor and coolant temp sensor. Car pulls great throughout the rev-range.
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Make sure both fuel pumps are replaced, check the ohms coming from your Crank Position Sensor as well.
Replacing all ignition components is probably a good idea anyways, if the car has sat for long.@IRON-E30 aka Edwin:D -
Could be leaky injector(s) flooding the cylinder(s) and releasing pressure in the fuel lines...Comment
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