Crankshaft Speed Sensor need help

[joedir1]

Does anyone know if a faulty crankshaft speed sensor on my 1994 540i can cause the DME to not talk to the main motr and fuel relays causing no fuel to pump and the car not to start? thanks.

[E34-520iSE]

That's correct - No crank sensor signal means the engine won't start.

HTH,

Shaun M

[joedir1]

does the same goes for the camshaft speed sensor?
I know for sure the car will not start if the oil level sensor does not work.
thanks

[E34-520iSE]

Can you tell us exactly what's happening here? Are you suspecting that your cam sensor and oil sensor are duff too? I don't know about V8's but my M20 will start no matter what the oil pressure sensor says

[joedir1]

Well here it goes...car stalls one night. Tow to dealer. They notice a wire is burned up and recommed new wire harness...$ 2500 installed. Only paid $ 2000 for car. Got it home and replaced the one wire that went to the oil level sensor. Car starts right up. Dealer did say at time that either camshaft or crankshaft sensor showed a fault, but at that time car did start so we just kept driving. 2 months later car stalls and barley makes it home. So since not so confident in dealer, we start to check it out. Replace some relays, and oil level sensor since it was burned up. Car still will not start, even though I know fuel pump works as I by passsed relay. Put in new main relay also and still no start. THough about it more today and remember the fault the dealer mentioned. Since we put in a new camshaft sensor, the only one left is the crankshaft sensor. THANKS alot. my kid is really bummed out with out his ride...and I cant give up on it. Its a really cool car.

[Ross]

A bad crank position sensor will cause a no start because of no spark. Sometimes they can be brought back to life briefly with a well placed blow to the sensor.
If your no start is because of no spark the CPS could be the trouble.

[Bill R.]

know that the pump works because you took the hose off and bypassed the relay and gas came out... did you hook up a gauge to verify how much pressure was there?

Well here it goes...car stalls one night. Tow to dealer. They notice a wire is burned up and recommed new wire harness...$ 2500 installed. Only paid $ 2000 for car. Got it home and replaced the one wire that went to the oil level sensor. Car starts right up. Dealer did say at time that either camshaft or crankshaft sensor showed a fault, but at that time car did start so we just kept driving. 2 months later car stalls and barley makes it home. So since not so confident in dealer, we start to check it out. Replace some relays, and oil level sensor since it was burned up. Car still will not start, even though I know fuel pump works as I by passsed relay. Put in new main relay also and still no start. THough about it more today and remember the fault the dealer mentioned. Since we put in a new camshaft sensor, the only one left is the crankshaft sensor. THANKS alot. my kid is really bummed out with out his ride...and I cant give up on it. Its a really cool car.

[joedir1]

I did not check the presure. The bypass tool that I made with a toggle switch and fuse ran the pump from the stop where that fuel pump relay goes.
I was just happy to see fuel come out of pump. When I put the relay back in the holder, no power at pump plug. This is why I replaced the DME main relay and still no power at plug. thanks for the replys...I appreciate the help....and my kids hockey team just played and tied the # 3 team in state....so all he needs now is his old Bimmer running.

[whiskychaser]

I was just happy to see fuel come out of pump. When I put the relay back in the holder, no power at pump plug. This is why I replaced the DME main relay and still no power at plug.

Maybe I missed something, but you only get power to the pump when the engine is running or being cranked

[joedir1]

I only have been able to get power to the pump when I use the bypass tool with toggle switch. Click switch on and I hear E-box fan, and pump sends out fuel. ( I saw it as I unhooked fuel line from pump) So as Shaun M said above, no crank signal, no message to DME to power up? I have replace a few sensors now and am willing to replace this one too, just trying to be more sure. Appreciate the commets....thanks ahed of time to all.