Auzeras 28 Report post Posted October 9, 2014 My M30 powered 735i runs ok but I feel like it lacks a bit of power and even if it's a cold or hot start it always idles at ~600RPM which is a touch low for hot and damn low for cold. It's got a million missed maintenance items from the PO which I'm working through, one of which is fixing up the fuel system. Already Done: I've already tried to fix a problem with the sender and made sure the pump fuel lines were on good in the tank, tank gasket was fresh and there was hardly any sediment in the tank, got the magnetic bits out with a neodymium magnet a few tiny bits remain, nothing to worry about. Filter screen on pump was in good shape. Fuel Filter - Replaced What want to check/do: Fuel pump - Pressure & Flow Injectors - Clean & rebuild (O-Rings, Filters) Fuel Hose - Replace all flexible lines Fuel Pressure Regulator - I think it's original since it's covered wit the same yellow flaky spray crud they coated the engine bay with before export. Doesn't seem to smell of fuel in the vacuum line but is there some sort of definitive test to make sure it's functioning? Is it likely to be good after 26 years or should I replace it? $150 I'd rather not spend if it is good. Anyone else have anything to add to that? I'll need to borrow a fuel pressure gauge (if anyone has one I could borrow that would be great) and I have no idea how to work out if the fuel pump is delivering good flow, is there a way to check that or should I not worry about that if the pressure is right and it's not loosing power at high RPMs? Injector rebuild - Will be building a rig to pressurise the injectors and pulse them to properly clean them. If anyone wants to rebuild their injectors at the same time let me know. Would be good to combine shipping or do a bulk order of parts & make the rig a bit more of a worthwhile build than for just one run of 6 injectors. Would also be happy to loan it out at the cost of shipping for those outside of Welly. I come up to Auckland regularly too so can drop it off up there. Only thing is if the fuel pump IS bad with low pressure etc, what are my options other than an OEM part? I've got access to 3D printers, lathes, milling machine, CNC router etc so I can easily fabricate a new pump holder. Will any aftermarket pump with better specs than the OE part drop in or does the flow & pressure have to be pretty carefully matched to provide good spray at the injectors? Cheers for any info/suggestions. Quote Share this post Link to post Share on other sites
yng_750 247 Report post Posted October 9, 2014 Injector cleaning usually runs cleaner through them with pulsing but also usually uses ultrasonic vibration to dislodge crap. As its a fuel air mix redo the intake manifold gaskets. And clean any idle control system Quote Share this post Link to post Share on other sites
Auzeras 28 Report post Posted October 10, 2014 Forgot to mention - Cleaned ICV & replaced throttle body gasket. Have got the manifold gaskets. Will do them too after media blasting and a paint job. Quote Share this post Link to post Share on other sites
