Weird Cranking in M30

[e34m30SF]

Hey everyone, just junked my m30 with my car since the block was cracked. not sure how the previous owner drove it, but that engine was toast. Got an engine from a donor 735iL and that engine is great, except I noticed one thing.

It's an intermittent problem, but when i go and crank it, from sitting overnight it jumps to life. When i try to start it when it's warm, it sounds as if it has been cranking for 10 seconds (start spins real fast) and it takes a good 5 seconds or so for the engine to turn over and run on its own. sometimes it will happen, but more often than not. i'm a bit paranoid about this donor engine breaking down on me, but so far it proved itself in the first 300 miles.

The sound can accurately be described as trying to start an engine that has a bad coil...it'll keep cranking but never turn over, but remember, that's just the sound. Again, starter seems to be spinning abnormally fast, yet the engine just doesn't "get it" until a few seconds later.

Lastly, my old original engine cranked in 1-2 seconds, every time but this one seems to be very tempermental. I will admit I'm OCD, but not sure if I'm just being overly-paranoid or there really is an underlying problem.

[BFEINZIMER]

fuel return check valve or sumthin

same problem here kind of embarrsing sometimes!

i need the part #

[whiskychaser]

It's an intermittent problem, but when i go and crank it, from sitting overnight it jumps to life. When i try to start it when it's warm, it sounds as if it has been cranking for 10 seconds (start spins real fast) .

Had a similar problem only a few days ago. I was convinced the starter was spinning but not engaging. Till I watched the fan blades going round And I will swear the engine was turning over faster than normal too. I think we get used to 'normal' sounds of the engine trying to fire or picking up. In my case the engine ran for a couple of seconds then died so I'm going down the fuel route. Perhaps something to think about?

[e34m30SF]

whiskeychaser, you've described it exactly. starter spinning but not engaging. fuel problems? *grumble* well, if it helps any, it does idle rough, though not unusual, yet when i accelerate, there is some hesitation. the usual electrical stuff is new (cap, rotor, wire, plugs) new rubber hoses all around, etc. mechanic (who i've been going for 18 + years) says it might be a fuel pump ready to go on vacation.