No Start, need help before car is towed!

[603Racing]

'84 325e - all original drive train and electronics

Yesterday afternoon, I tried to start the car, cranks fine but was not getting spark or fuel. When turning key, the main relay would not click. Then after 3 tries it clicked and the car fired right up. Drove it another 30 miles that day with no issues. Went to O'Reilly's last night to pick up wiper blades and Rotella T. When I came out, same issue. Except this time the main relay does click, but still not fuel or spark. I have no power at the coil. Fuel pumps do not function while I'm cranking the car. I jumped the fuel pump relay and the pumps kick on. I also swapped around the relays and put in a brand new main relay, still no fire or fuel.

All relay connections were clean, wires running to relays look good. ICV is new (wouldn't suspect that anyway). Timing belt has less than 5k on it. I'm going to go back later this morning with a meter to check ohms on the reference and speed sensors on the flywheel. The only other issue the car has had is it runs a bit rich, but I've traced that to a burned section of O2 sensor cable. But even that shouldn't cause no spark/no fuel.

My buddies '85 e28 had this same problem, turned out to be the security module had shorted and was cutting fuel and spark. He bypassed it and that fixed it. Does the early Eta have one of these? I saw a similar small black box under the headlight switch area with two similar green plugs running to it. Anyone familiar with this? Of course I left without writing down the part number off that black box.

[603Racing]

That "security" box I referenced is actually the OBC relay box.

I'm going to try this as well as test CPS. Though I will jumper it, not cut and splice just yet.
http://www.mye28.com/viewtopic.php?t=40739

[SmokeE30]

That "security" box I referenced is actually the OBC relay box.

I'm going to try this as well as test CPS. Though I will jumper it, not cut and splice just yet.
http://www.mye28.com/viewtopic.php?t=40739

Yes I just had to replace the obc relay box on my 85 325e try smacking it while cranking doing that a couple times got my car to hiccup to life so I replaced it but you can bypass it to get it running in a pinch too.

[603Racing]

Update:

5 hours of troubleshooting later. Luckily I have access to a lot of spares, so all this testing didn't cost much. I tested or replaced the following parts...

• CPS - both of them on flywheel
• FPR
• Relays - main, o2, fuel. Used 3 different mains and fuels just to be sure
• DME
• several fuses just in case
• coil
• in tank pump was replaced 2 weeks ago
• plug wires are less than 2 years old
• jumpered green wires to OBC relay box - no affect
• jumpered fuel relay, pumps kick on
• temp sensors replaced 2 weeks ago
• ICV replaced 1 week ago

So, after all this the car cranks but will not start. The list is not in order exactly. I have greatly narrowed the search. I believe I had two issues going on, narrowed down to one. I was getting no spark previously and no fuel pumps upon cranking. The last thing I did yesterday was jumper the fuel relay again, letting it run for about 10 seconds before cranking. It fired right up then immediately died. So I know I don't have fuel pressure. I know, I know, should have tested FP before, but neither parts store I'm close to had a complete kit, they are missing the exact parts I need to T in the gauge. Anyway, I crawled under the car and the high pressure pump and filter are very old and the pump is noisy. I have another set of in tank and external pumps, I'm going to put those on tonight along with filter. If that doesn't work I'll go buy a FP gauge.

I've only been driving this car for a couple weeks, so I haven't had a chance to look over all details of the car. So no ball-busting for not looking at the pump sooner! ;)

[603Racing]

Ha, I know I've done at least an adequate job of troubleshooting when there aren't responses to my problem.

Another update... fuel pressure is effectively zero. It will no longer fire briefly even if I let the pumps run for 30 seconds. Put a pressure gauge on it, nada.

Being fairly certain it was the high pressure pump, I set out to replace it. Once again working in the parking lot of the auto parts store. Working against the rain, impending darkness, and decades of rust, I discoverd the pump setup was the "original" e30 setup with the dampener and several short, hard to disconnect hoses. No worries though, I didn't even get to the hoses. The third terribly rusted 10mm nut/bolt I tried to remove was having none of it. Thouroughly sprayed with PB, the bolt still bent and twisted while the nut started to round off. Many explatives were produced and a wrench may have been used as a weapon of massless destruction on the rusted bracketry of German over-engineering.

End story: I had spent one-too-many evenings on that parking lot and hauled my car to a buddies BMW specialty shop. I will post the final fix, but until then... F IT, I'M OUT!

[dsphil]

New harness perhaps. Just a thought.

[603Racing]

As I suspected, no fuel pressure. New high pressure pump going in today as well as a new filter.

[603Racing]

Turns out I had multiple issues, so I don't feel so bad in handing it over to the shop. The high pressure pump was bad and I also had a intermittent short in the wiring to the OBC relay box.

Man do I hate intermittent electrical problems!

Pump replaced, green wires to relay box jumpered, new fuel filter because existing one had junk in it... car starts and runs like a champ again.