engine swap M42 cranks but no start

[tashakes]

This morning wanting to take the 02 to work, get in like I normally do, crank, no start. Last night it was working perfect, and since I finished the swap a couple of months ago no issues. Fuses are good, relays seem ok. Will check fuel pump this weekend. Any suggestions?

[Arash2002tii]

Check spark too.

[morfiya.pb]

Check for fuel or spark first thing that comes in my mind crank sensor

[M3M3]

Main and fuel relays.

[ClayW]

Main and fuel relays.

+1 on the relays. I thought mine were okay on the M42. a few months later (too busy with other stuff), I replaced them because I ran out of other things to check. Fired right up. 

 

They're like $13 each from the dealer. Get `em.

[Arash2002tii]

+1 on the relays. I thought mine were okay on the M42. a few months later (too busy with other stuff), I replaced them because I ran out of other things to check. Fired right up.

They're like $13 each from the dealer. Get `em.

Just swap them with known good relays first to see if they even need replacing. Also remember that just because a relay clicks does not mean it's good.

[tashakes]

Are the relays regular ones or special dealer-only type of thing?  I have some extra relays around that I can try this weekend if so.  Otherwise, will have to buy the ones that are needed.  

 

I read on the E30 forums that if the CEL does not light up, then it is the fusible link, but I am sure I dont have it because it is supposed to be located on the trunk by the battery on the E30.  The skinny wire with the fusible link supposedly powers the ECU and blows quite often.

 

After the relays, if it does not fire up next will be to check the CPS.  Stay tuned.

 

Thanks for the ideas guys, always good to know I can rely on the good ol FAQ!

[tashakes]

Ok. Here is what I have done so far

Tested relays all good (bench tested with test lamp)

Replaced relays in case

All fuses good

CEL no faults

Tested fuel pump (jumped) works fine

BUT no power to pump when cranking (tested with test lamp)

Leads me to think crankshaft position sensor. I read that pump only fires up when crank movement is detected.

Suggestions?

[Arash2002tii]

Ok. Here is what I have done so far

Tested relays all good (bench tested with test lamp)

Replaced relays in case

All fuses good

CEL no faults

Tested fuel pump (jumped) works fine

BUT no power to pump when cranking (tested with test lamp)

Leads me to think crankshaft position sensor. I read that pump only fires up when crank movement is detected.

Suggestions?

Seems like you're on the right track. Can't remember if the tach is supposed to show RPM while cranking, but if it is and your needle just sits dead then that might just help confirm.

 

You can look to see if the sensor is covered in gunk, and that it is correctly positioned in relation to the toothed wheel.

 

It does seem like the most likely culprit if you've already replaced the relay and the pump still isn't being commanded on.

[tashakes]

Thanks the tach needle is completely dead while cranking.

[ClayW]

 Also remember that just because a relay clicks does not mean it's good.

 

This. When I first checked my relays, I could hear and feel the fuel pump relay clicking, so I assumed it was good.That assumption cost me hours of diagnostic time, which resulted in months of downtime. 

 

I replaced the relays with new and she fired right up. Cost me $26.

Seems like you're on the right track. Can't remember if the tach is supposed to show RPM while cranking, but if it is and your needle just sits dead then that might just help confirm.

 

You can look to see if the sensor is covered in gunk, and that it is correctly positioned in relation to the toothed wheel.

 

It does seem like the most likely culprit if you've already replaced the relay and the pump still isn't being commanded on.

 

 

After testing or replacing the crank position sensor, check the cam position sensor. that could throw it off, too.

[tashakes]

To close this case, replaced crankshaft position sensor and everything is now ok. $79 from autozone.

[dlmrun2002]

Good to know for us M42's. Thanks for posting on R3V board too. Now  I know why I carry extra relays, crank and cam sensors in my 318is { extras from a 2nd engine }

 

dlm ny country

Edited February 1, 2015 by dlmrun2002