tempermental E30

Post Sat Dec 07, 2013 7:51 pm

Having trouble with a 1988 325iC, all stock. Cannot get it to start. No signal to fuel pump. I have spark, but no signal to run fuel pump. Replaced: crankshaft position sensor, fuel pump relay, DME relay, Ignition harness, main engine ground, swapped ECU with same result. I can jump the Fuel relay and make the fuel pump run, but cannot start. When fuel pump is jumped and running, it is moving fuel. Any ideas???

Post Sat Dec 07, 2013 7:53 pm

Have you checked the fusible link in the power cable for engine loom?

Post Sat Dec 07, 2013 8:00 pm

No, what is the easy way to find it? There were no weird things to make it not run. It was running and I parked it. The next day, no start. The crankshaft sensor was wearing on the pulley though, if that caused some king of short...?

Post Sat Dec 07, 2013 9:50 pm

Just take a look at the power terminal under the bonnet, assuming the battery is in the boot? There should be a big thick cable in a clamp (starter cable) and a much thinner cable in it's own clamp with it's own little terminal. Check for battery voltage at the smaller terminal - although tbh if you have a spark and can make the fuel pump run by jumping the fuel pump relay, chances are you have power here.

Post Sun Dec 08, 2013 3:45 pm

Anyone know of anything else that will shutoff the fuel pump only? Immobilizer, some sensor, like oil or something? Any ideas out there?

Post Sun Dec 08, 2013 3:48 pm

You say you jumped the fuel pump and it ran. Did you do this at the pump, or from the fuel pump relay? If it's the former, then you need to go back and check that the wire from the relay to pump is ok.

Post Sun Dec 08, 2013 9:35 pm

Are you sure the relays are in the correct place? DME relay is a five pin one with two switched outputs (87). One output powers up the ECU, so will give sparks, and the other output supplies the injectors and the COIL of the fuel pump relay.
If this latter output is missing, the injectors won't fire and the pump relay won't switch on, although it will work if the relay is bridged.

Post Mon Dec 09, 2013 6:15 pm

I bridged the relay of the FP at 87 and 30, (I believe). They have been replaced both and in the same position as they were. Four and five prong respectively. It still makes sense that the DME relay is the issue

Post Mon Dec 09, 2013 6:47 pm

You can bypass the DME relay in the same way as you bypass the pump relay. Link 30 to both 87s.
Unclip the socket and check that there's a wire connected to the centre pin. Of the three, only the DME relay has any connection to this pin.

Post Fri Dec 20, 2013 11:45 pm

I'm going to start with the harness this holiday week looking for short, etc. Any ideas how to tackle this, where to start, etc?
I'm guessing I will start by peeling back the outer insulation and start following everything along. From there...?

Post Sat Dec 21, 2013 10:42 am

bmtrblu wrote:I'm going to start with the harness this holiday week looking for short, etc. Any ideas how to tackle this, where to start, etc?
I'm guessing I will start by peeling back the outer insulation and start following everything along. From there...?

All you're likely to end up with is a very tatty looking harness. It's extremely unlikely that there's anything wrong with it, unless one particular fault has happened in the past. Pull off the plug to the oil level sensor (in the top of the sump, right below the alternator), roll back the rubber boot, and examine the condition of the brown/orange wire. If it is burnt, then your loom could well be faulty, with the possibility of multiple random shorts, where this wire has melted into others along most of the length of the loom. If this is the case, buy yourself a fresh loom. Facelift 320 and 325 looms are identical.
Have you done everything I've mentioned in my previous posts? It's difficult to solve problems if you don't do the tests and provide feedback, so that I can suggest the next step.

Post Sat Dec 21, 2013 6:04 pm

The relays are in the correct position, I have not jumped anything yet. I will be doing that this week also. I am a little unclear about the route for connecting, the 30 vs the 87...?

Post Sat Dec 21, 2013 6:42 pm

Pull out the relay and identify the pin numbers of its socket. These are marked on the relay itself, either by the pins or on a diagram printed on a side of its case.
Take a 4" piece of wire, strip off about 15mm of insulation at each end, and stick the ends down the sockets (30 and 87) so that the wire makes contact with the buckets. DME relay has two 87s, so you will need two pieces of wire with one end of each twisted together to push down any one of the sockets, and the other two ends down the others.

Post Sat Dec 21, 2013 9:31 pm

Cool, I see, so jump the DME relay, and then the FP relay. Thanks. Wasn't completely sure. ..

Post Mon Dec 23, 2013 10:57 pm

Ok, Brian. I inspected the wires as you said, everything looked ok, nothing burnt or loose, or unusual looking. I jumped the DME relay and the FP relay as you said. The car started right up. Is that good news or bad news. I think I have over analyzed this so much, I am clueless now.

Post Mon Dec 23, 2013 11:37 pm

Right, so now we know that there's nothing fundamentally wrong with the engine. I hope all those parts you've fitted weren't new!
Remove the links, keep the relays out, and switch on the ignition. Push the DME 5 pin relay slowly into its socket and listen to hear if it clicks when the pins make contact. Should click again when you pull it out again.

Post Mon Dec 23, 2013 11:57 pm

No click...

Post Tue Dec 24, 2013 12:21 am

Do the same with the fuel pump relay.

Post Tue Dec 24, 2013 12:40 am

I actually misspoke on my previous post. The reason it did not click was because the battery was still dead even after letting it run. (May need a new one to top this all off!).
So. Yes the dme relay clicks when connected and disconnected

Post Tue Dec 24, 2013 12:41 am

FYI. Nothing from fuel pump relay.

Post Tue Dec 24, 2013 10:29 am

No click from the pump relay is correct.

1) With both relays jumped, the car starts and runs.

2) The DME relay clicks when pushed in or pulled out with the ignition on.

3) The engine will not start and run with the DME relay fitted, and just the pump relay jumped.

If all three of the above are correct, I can't see how it can be anything else than a dud DME relay, or that you have fitted an incorrect relay.

Post Tue Dec 24, 2013 11:24 am

That all sounds correct. I will go buy another one today and let you know. Thank you again for your time spent on this.

Post Tue Dec 24, 2013 1:44 pm

Can you post a close up pic. of the circuit diagram on the side of the relay case?
It's a fairly simple device inside - you should be able to see what's wrong with it if you take the case off.

Post Tue Dec 24, 2013 5:46 pm

The cover is completely blank.

Post Tue Dec 24, 2013 5:57 pm

I ordered the relay, from a different shop this time. It will be here at 2 o'clock my time.

Post Tue Dec 24, 2013 9:28 pm

That took care of it. Can't thank you enough. Will get new battery for it and then good to go. Thanks again.

Post Tue Dec 24, 2013 9:41 pm

So it was the DME relay then. The incorrect one you have had in the car is probably a change over type, and would likely have caused a drain on the battery while parked up, so don't totally condemn your battery just yet.

Post Tue Dec 24, 2013 11:57 pm

Put the new one in and drove it and so on, but barely enough strength even to light up the dash lights. Will get a new one Friday. What is the best way to look for battery drain after I put the new one in?