Need Help Getting M50 Started

[kevdeno]

I've got a 1987 325e with a 1992 non-vanos M50 installed, DME 403 (green), no EWS.

Problem: No fire whatsoever. Engine cranks, but doesn't even catch the tiniest of combustions.

CONFIRMED
- Green ignition wire powers up in on/start position.
- Black/Yellow wire powers up in start position.
- Starter engages and turns engine.
- Main relay powers up.
- Fuel pump relay and pump power up during cranking.
- Fuel lines are connected: from pump to silver metal line under intake man. (goes to front of engine), return to black metal line under intake man. (goes to rear of engine with fuel pressure regulator). Charcoal canister never was disconnected throughout the entire swap.
- Fuel reaches engine.
- Injectors receive power, ground and signal from DME.
- Coils receive power, ground, and signal from DME.

What else is there that could go wrong?
- The DME gets signal from the crank position sensor, otherwise it wouldn't send a signal for spark or fuel injectors, right?
- The engine hasn't run for more than a year. Could the injectors plug up?
- What about the fuel pressure regulator? Could it plug up?

QUESTIONABLE STUFF
- Spark plugs are in good enough shape to make spark, but are a little black and worn. I'll be replacing them in the near future.



Anyone have any ideas? This one's a tough one. I'm looking for an unturned stone that I can't even see right now.

[FredK]

How fresh is the battery you're using? How long did you crank for? If the engine has been sitting for a while, it sometimes takes a nice long ole crank to get it started.

Is the engine ground strap connected from the engine mount arm to the M8 stud on the E30's frame rail?

[kevdeno]

How fresh is the battery you're using? How long did you crank for? If the engine has been sitting for a while, it sometimes takes a nice long ole crank to get it started.

Is the engine ground strap connected from the engine mount arm to the M8 stud on the E30's frame rail?

The battery is maybe a year and a half old. It holds a charge quite well, and can withstand many, many starting attempts with no noticeable degradation. I frequently put the charger on it to keep it fully charged.

So far I've cranked the engine multiple times, in excess of 50 times. Some for as short as a half second, some as long as 8 seconds. I'd say the majority of the time I crank it for 4-5 seconds. A lot of the time I try it many times over, one right after the other, for 4-5 seconds each.

Edit: I used the ground strap from the E30. It's on the driver's side. It connects to the driver's side motor mount.

[FredK]

What flywheel/trans combo are you using? Is the little alignment dowel in place between the crank hub and the flywheel?

[kevdeno]

What flywheel/trans combo are you using? Is the little alignment dowel in place between the crank hub and the flywheel?

Using an E36 transmission. I never unbolted it from the M50. I dropped it into the car in one piece. The whole thing came out of a running 1992 325i 5 speed. Completely stock.

[FredK]

How are the power wires hooked up? Do you have a digital camera that you could take a pic of the power hookups next to the firewall?

Fuel rail ground hooked up? It's a small wire that loops over the engine lift eyelet at the front of the engine.

Also, is the donor car an automatic?

[kevdeno]

How are the power wires hooked up? Do you have a digital camera that you could take a pic of the power hookups next to the firewall?

Fuel rail ground hooked up? It's a small wire that loops over the engine lift eyelet at the front of the engine.

Also, is the donor car an automatic?

I can take pictures tonight when I get home from work. I won't try to explain the connections until I get home and can provide pictures with my description.

The fuel rail ground is hooked up, and tests ok with a test light.

The donor car is a 5 speed.

[BigD]

Pull out a plug after cranking a bit. Is it wet with fuel? That will tell you a lot.

[kevdeno]

I took a picture of the power distribution at my firewall. Notations are on it.

[kevdeno]

Pull out a plug after cranking a bit. Is it wet with fuel? That will tell you a lot.

Not wet.

I just don't get it. I still don't know if the injectors would get clogged. Surely not all 6 at once. I confirmed that they receive positive power when the key is in on and start. I confirmed that they receive ground trigger from the DME during crank.

[BigD]

Not wet.

I just don't get it. I still don't know if the injectors would get clogged. Surely not all 6 at once. I confirmed that they receive positive power when the key is in on and start. I confirmed that they receive ground trigger from the DME during crank.

Just curious, how did you confirm this? Do you have an oscilloscope? I mean, the period is microscopic.

Do you have fuel in the rail? Maybe you got the lines backwards. edit: checked your first post, and you seem to think that the fuel gets to the rail... but like you said it doesn't make sense, you're not checking something right. You can't clog all 6 injectors so they let NO fuel through (at that pressure, no way even 1). If you want to perform a sanity check, put 12v across one of them, they make a solid click. You're either not getting fuel or signal at the injectors.

[kevdeno]

Just curious, how did you confirm this? Do you have an oscilloscope? I mean, the period is microscopic.

Do you have fuel in the rail? Maybe you got the lines backwards. edit: checked your first post, and you seem to think that the fuel gets to the rail... but like you said it doesn't make sense, you're not checking something right. You can't clog all 6 injectors so they let NO fuel through (at that pressure, no way even 1). If you want to perform a sanity check, put 12v across one of them, they make a solid click. You're either not getting fuel or signal at the injectors.

Well, I didn't use an oscilloscope. I used a test light. After reading through the BMW electronic troubleshooting guide I learned that the fuel injectors get a constant positive wire from the ignition during on and start. The DME sends a ground signal when needed to complete the loop and open the injector valve. I simply hooked my test light to positive, the probe to the ground on an injector and cranked away. I got a blinking test light. Tried it on many injectors and received the same result. As far as the injection period being microscopic, you could be right. I just don't know what to do with my findings.

Yep, I've got fuel in the rail. And I've double, triple, and quadruple checked that my lines aren't backwards. I made that mistake early on, weeks before posting this thread, and fixed it.

Back to the injectors. I went out and tested them. New wire straight to the injectors and nothing. No click. No fuel. Nothing. All 6 are this way.

What the hell? All 6 failed?

[BigD]

What do you mean by new wire? Get a spare battery or your charger, and hook it up straight up to the poles of the injector (sounds like you already know which is signal and which is power). If it still doesn't click, smack it good with a wrench. I think it's pretty hard to really kill these things, it's just a solenoid. But they can get gunked up. Although like you say, I doubt all 6 would be THAT bad but... iuno. I personally took my pinkies to an injector shop. For $120 bucks taxes in, I had a set of injectors as good as brand new.

[kevdeno]

What do you mean by new wire? Get a spare battery or your charger, and hook it up straight up to the poles of the injector (sounds like you already know which is signal and which is power). If it still doesn't click, smack it good with a wrench. I think it's pretty hard to really kill these things, it's just a solenoid. But they can get gunked up. Although like you say, I doubt all 6 would be THAT bad but... iuno. I personally took my pinkies to an injector shop. For $120 bucks taxes in, I had a set of injectors as good as brand new.

Yeah, I didn't explain the "new wire" thing well. What I meant is I used two pieces of new wire from a roll and wired each injector straight to a battery. I got no clicking sound or fuel leakage. (I got the injectors removed by the way) And yes, each injector has a red/white wire (positive), and a brown/unique color wire as well for the ground trigger.

[BigD]

Yeah, I didn't explain the "new wire" thing well. What I meant is I used two pieces of new wire from a roll and wired each injector straight to a battery. I got no clicking sound or fuel leakage. (I got the injectors removed by the way) And yes, each injector has a red/white wire (positive), and a brown/unique color wire as well for the ground trigger.

Did you try reversing the poles for shits and giggles (if they don't do shit this way, then they're either dead or you have it backwards anyway, so why not)? But it's not like your injector rail has the poles reversed (provided they indeed do get power and signal)... so I guess all of them are somehow fried...?! Try to jack one or a set from someone to try... like say if you break 'em or they work you'll buy.