M42 cranks but won't start

[Mohit]

My 91 318is has been running fine since I bought it a year ago, no issues at start up (except the hot start issue that every noob has). On Saturday I jacked the front of the car up to try to install my z3 short shifter, but decided I didn't have enough time, so I let the car down. Didn't start the car until this morning (Monday), and it wouldn't start. Battery is fine, all lights show up, it cranks, but it won't start. It seems like it wants to start, but it just won't catch or something. There wasn't any issues before indicating something was going bad, so I don't know what to do. Here's a video of what it sounds like.

http://www.youtube.com/watch?v=FfqOVKDbvs8

[Dj Buttchug]

fuel
air
fire
comp
time

what do you not have OP?

[Mohit]

fuel
air
fire
comp
time

what do you not have OP?

I dunno where to start. I tried checking for spark by putting the first spark plug onto the engine and cranking, and I saw blueish sparks. Here's a pic of the spark plug

[Dj Buttchug]

those need to be changed. Are you sure the engine is getting fuel? I think your fuel pump might be crapped out conveniently when you started working on the car.

[Mohit]

those need to be changed. Are you sure the engine is getting fuel? I think your fuel pump might be crapped out conveniently when you started working on the car.

Okay, I'll buy some new ones. I tried turning it on while WOT to clear out fuel because this guy said so, and let the plugs dry. It started after cranking for ~8 seconds, with a super rough idle. After letting idle for about a minute I revved it about 1.5k RPM and started squealing really loud. It's squealed like this before in the morning when it was around 50F outside.

https://www.youtube.com/watch?v=gkP5CfhbS34

[Dj Buttchug]

belts loose!

[Mohit]

belts loose!

Any belt you think in particular?

[d_elson0]

Mine did the same thing. My battery seemed fine, would crank all day and lights would all work. Threw some cables on it and jumped after a minute or so of being hooked up. My 2cents

[noypi2]

I have the same problem. I replace the fuel pump relay and it works. I have a M10.

[Mohit]

I changed the valve cover gasket and replaced the spark plugs, and it starts fine now but has a rough idle. It smells like gas, so it's running rich for sure. I guess I'll start with the fuel pump relay.

[roguetoaster]

If it's running rich, or running at all, you should not need to replace the fuel pump relay.

Is it only running poorly when warm? If so, it may be the oxygen sensor. Bad idle from start up? Probably vacuum leaks or ICV in need of cleaning.

Beyond that it could be any number of things, from the catalytic converter to the air flow meter. Be sure that the wire on the passenger side under the plastic cover (the one that covers the 3 relays) in unplugged. After that I'd check the position of the throttle at 0% input to make sure it's seated.

[Mohit]

If it's running rich, or running at all, you should not need to replace the fuel pump relay.

Is it only running poorly when warm? If so, it may be the oxygen sensor. Bad idle from start up? Probably vacuum leaks or ICV in need of cleaning.

Beyond that it could be any number of things, from the catalytic converter to the air flow meter. Be sure that the wire on the passenger side under the plastic cover (the one that covers the 3 relays) in unplugged. After that I'd check the position of the throttle at 0% input to make sure it's seated.

It's a rough throttle at start up, not really even driveable right now. I am about 70% sure my catalytic converter is empty, according to the muffler guy. He said that it was basically hollow, and this was about four or five months ago. That wire you're talking about is unplugged, I had that hot start problem when I first bought the car a year ago. I also had a smoke test done when I bought the car and everything checked out, but I guess that could be bad now.

Thanks.

[roguetoaster]

Well, if it truly started out of the blue it should to be an ignition issue, either bad a bad coil (did you verify spark on all 4?) or an ECU issue. It could still be a coincidental vacuum leak, but this would probably not be an issue at operating speeds.

As to the catalytic converter being empty it won't impact engine operation, but will make the exhaust smell more of gasoline.

It may be worth checking the vibration dampener/crank wheel. Some time ago mine separated without failing completely (the trigger wheel rotated on the vibration dampener) and would still start and run for a very short time before stalling, but was 100% undriveable.

[Mohit]

Well, if it truly started out of the blue it should to be an ignition issue, either bad a bad coil (did you verify spark on all 4?) or an ECU issue. It could still be a coincidental vacuum leak, but this would probably not be an issue at operating speeds.

As to the catalytic converter being empty it won't impact engine operation, but will make the exhaust smell more of gasoline.

It may be worth checking the vibration dampener/crank wheel. Some time ago mine separated without failing completely (the trigger wheel rotated on the vibration dampener) and would still start and run for a very short time before stalling, but was 100% undriveable.

I only checked spark on one of the the plugs. I don't know about the vibration dampener/crank wheels, it doesn't seem to stall.

[Mohit]

I verified spark on each plug, and I tried a stomp test and no codes came up. I'll try cleaning to ICV next.