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View Full Version : Hard starting 750


jmhuot
03-22-2006, 09:32 AM
My 750 is very hard to start. I suspect a problem with vacuum and fuel, but looking for anyone who may have had this problem. I actually have to apply throttle to get the car to start. It will start, but then just stumble and shut off. If you don't apply some throttle it will not stay running. Once started though, it will stay running and idle. It is the M70 engine and it's in an '88 750il. Any ideas or help is appreciated.
joshua43214
03-22-2006, 08:18 PM
Could be far too many things to mention, this is one of the few cars I have ever worked on that I knee jerk on hooking up to the diagnostics and pull codes so I would atleast have an idea of where to start. Its possible if you wrote a very long highly detailed description of starting and idling someone might be able to make a good educated guesse, or an experienced tech might be able to pin point it if they started it themselves. Please don't get me wrong, I love the 750's, there is something invigorating about v12's, but the techs at the dealer will hate you if you waltz in with it and you are likely to get the guy at the bottom of the foodchain working on it. So, either drive it by a dealer and pay for the quick check, or gives us loads of details.
shogun
03-24-2006, 01:24 PM
First of all, is it after long time engine off only?
To check if the fuel check valve in the tank on the fuel pump is o.k., turn ignition to 2 but do not start engine. In this position the fuel pump starts working till the required pressure is there. If the check valve is defective, fuel returns to the tank and fuel vapour starts to develop.
Do that 2 times,ignition on position 2 for about 10 seconds, switch ignition off and on again. Fuel pump stops working if required fuel pressure is reached but engine is not switched on.
Many other things could be the problem: faulse air, air temperature fller, coolant temp sensor, ignition wires.
How about the distributor caps and the distributor rotors? Have you removed them and had a look at them? Some cars still have the first ones inside and they were never changed.