e38 help

[yng_750 247]

hey guys having a little trouble with my 94 e38 740i

it has always started first pop

until about a week ago when it cranked for about 10 seconds before catching and running fine

then yesterday morning it would only crank over but would fire at all, no coughing or spluttering at all

then after trying to start it about 4 times for 20 seconds each time it started and ran fine

once it had warmed up it started again with no hesitation

that evening it did the same thing and i had to try for a while to start it but when it started it ran fine

this morning it did the same thing but wont start at all

i smelt the exhaust after cranking for a while and could smell no fuel

i had a play this evening to rule out a couple of common issues i have read about

removed the fuel pump relay and opened it up and checked it moved

when i tried to start the car it did not react

i then held it open with a piece of plastic

after this i could hear the fuel pump running under the car (quite a loud hum) but still no sign of starting at all

i will check tomorrow in daylight whether it has fuel pressure at the rail and im not sure if i can with coil packs but will try to check whether it has spark

anyone have any idea what my problem could be?

or easy tests i could do to narrow down the issue?

thanks in advance

[yng_750 247]

btw there are no warnings or check engine light etc on the dash

[yng_750 247]

from reading around sounds like it may be my crankshaft position sensor

will try to give that a test tomorow

[Greg111 13]

Was thinking cam or crank sensor, seen a few V8s with cam sensor faults doing the same thing.

[yng_750 247]

on a whim i tried to do a stomp test

turns out my check engine light doesnt come on at all suspected blown bulb

though cam and crank angle sensors supposedly give some strange error codes

its been raining heavily here and the sensor is meant to run around 650 ohms im told, so any water in the plug will mess with things another thing to check

[yng_750 247]

bah enough of this now

im watching some boston legal and going to bed

deal with this crap tomorow

[yng_750 247]

i pulled the cam position and crank position sensors

the cam tests look normal

however the crank sensor apparently should read around 650 with the multimeter on 2Kohm setting

mine reds nothing there and only read when i put the meter in 200Kohm setting and then it just slowly raises in resistance constantly but if you touch the pins it goes back to where it started

so somehow my inductance pick up coil is acting like a capacitor

not much to go on but everything else is checking out so im gonna take a wild stab in the dark and replace it

anyone know where i can get a crank sensor on a saturday in taupo.......

[yng_750 247]

Back up and running

thanks to HARTGE535i for the crank sensor

as a quick tip to anyone running into either long cranking issues or no start at all take the engine cover off and at the front of each of the plug boxes there is a plug on the intake side

the left one runs to the crank position sensor and the right runs to the cam position sensor

you can test them in place just unplug and measure the resistance between pin one and two it should be around 550 ohms

if its much higher like mine was then its probably stuffed

[BM WORLD 1283]

good work . i bet your glad its back up and running

[yng_750 247]

yup

took the opportunity to do a coolant change

doing an oil change also this week

probably going to sell it in the near future as im hopefully off to europe in September