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poohbear15 07-26-2010 02:25 PM

740i shuts off
please help, ok my car is a 1995 740i, while drivin or just parked it shuts down. when cold the car starts right up n runs sounds drives great. then suddenly it just shuts off without out warning after about 20 mins. i have no check engine light. after it shuts of it usually starts right back up but will only stay on for a minute or so then shuts off again. any help will be greatly appreaciated

btw car has 104k n i sprayed the maf with maf sensor fluid

balance 07-26-2010 02:52 PM

I'm thinking fuel pump, but that is just a guess.

poohbear15 07-26-2010 04:09 PM

thnx how can i check that, does anybody else have any suggestions

FABOCH 07-26-2010 04:51 PM

fuel line clogged...bad fuel filter or bad fuel pump

poohbear15 07-27-2010 05:20 AM

thnx for the help, ima check all the fuel components, ive also heard it cud b the crank ps or the camshaft ps, any insight on this

poohbear15 07-27-2010 12:16 PM

bump please help

tommyb2b 07-27-2010 02:51 PM

I would put money on the Fuel system. The fuel pump is under your rear seat and very very easy to get to. Listen to see if it hums. I would replace the fuel filter and check the fuel lines as well.

poohbear15 07-28-2010 03:27 AM

thnx guys, pay day tomorrow so ima change the fuel filter and check the fuel pump

balance 07-28-2010 10:20 AM

If you have access to one, get a tool that checks for fuel pressure at the fuel rail. Then start driving with the gauge in the car and see if the pressure drops before hesitating or shutting off.

poohbear15 07-28-2010 10:54 AM

dont have access to one of those, r they expensive?

balance 07-28-2010 11:06 AM

Not really, a cheap pressure check set is about $30. It's raining like crazy outside so I can't check it myself, but first find out if the fuel rail has a shrader valve, before buying the set, as that is what you connect the gauge to. A shrader valve looks like the air valve on your tires, and it should be somewhere on the fuel rail, but some cars don't come with them.

FABOCH 07-28-2010 02:38 PM

or a BAd MAF sensor

poohbear15 07-28-2010 03:35 PM

ok, ill check that out as well

poohbear15 07-28-2010 03:40 PM

i disconnected the maf n the car ran a lil rough but stayed on for a while. eventually it shut off just like it normally does ao i think its the maf

balance 07-28-2010 04:23 PM

If you disconnect the MAF while the car is at idle, it should run smooth. If it runs bad, and when you disconnect it, it runs good, then you can be sure that it is the MAF.

poohbear15 07-29-2010 07:06 AM


Originally Posted by poohbear15 (Post 5356837)
i disconnected the maf n the car ran a lil rough but stayed on for a while. eventually it shut off just like it normally does ao i think its the maf

sorry meant to say i dont think its the maf

poohbear15 07-31-2010 08:45 AM

i took the car to a mechanic n he said the car didnt shut off on him n no codes came up, so even he doesnt know wats wrong.......but he did tell me its not the maf or the fuel system so ima try the camshaft position sensor, ive heard that cud b it

balance 07-31-2010 02:03 PM

The Camshaft Position Sensor should be throwing a code if it is bad. You could test it the same way you tested the MAF, disconnect it, turn on the motor, let it run and see if it shuts off by itself again. The motor will run off of the crankshaft position sensor until it is re-connected, but I wouldn't reccomend driving it this way.

poohbear15 07-31-2010 09:47 PM

wheres the crankshaft position sensor located, i wanna try that one

balance 08-01-2010 09:05 AM

It should be somewhere around the harmonic balancer, but if it was bad, the car would not start at all. I'd start with the cam. Are there any other symptoms?

poohbear15 08-01-2010 01:26 PM

yeah i changed the cam postition sensor and it didnt help, there are no other symptoms it starts up fine runs smooth n powerful n then shuts off. my dad keeps tellin me to change the coild but idk if i shud, wat do yall think......btw i have no cel

poohbear15 08-02-2010 07:24 AM

anybody help, shud i change the coils i dont wanna if it doesnt make sense

balance 08-02-2010 08:37 AM

I am 99% sure that it is not the coils. These cars have 8, and even if 3 or 4 went bad AT THE SAME TIME, the car would probably still stay running. Also, if a coil goes bad, it usually stays bad. Sorry man, but I'm all out of logical ideas. If the mechanic knew what he was talking about, and it is not the fuel system, and the car does not throw any codes, then it could be anything from a loose connection somewhere, to a bad ECU. You could try checking to see if voltage drops right before it shuts off? If anything else pops up, please keep us informed, and I will try to help out.

poohbear15 08-02-2010 09:07 AM

im actually checkin the fuel system now just pulled out the rear seat, i really appreciate everybody's help, thnx alot i will stay posted

poohbear15 08-02-2010 05:59 PM

the fuel filter was the culprit, i swapped it out with a new one from bmw, now the cars running perfect. i checked out the old one n it was severely clogged im suprised the car wud even stay on as long as it wud.....anywho thnx everyone for all ya help n suggestions much appreciated

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