Fuel pump/starting problem for the electricians and experts

[genphreak]

Excellent. Now we're getting somewhere. Please don't be frustrated; we'll get it worked out for you. I didn't mean to come off as a jerk in the earlier post -- I was impressed with the information, just believe that there're better ways to approach the diagnosis.

best, whit

Class sleuthing Whit, I'm sure I am not the only one following this chase... I'll put an early bet on with you and say some of those those coils are bad...

Seriously, with a BeMtroubleuw the is often in the detail... so this thread provides a clear lesson for many: Azale (good work on your posts mate) made a huge effort to explain things clearly and probably has a solution now. We should all try to take as much care when posting, to be specific and explain the context within which we describe our actions/deductions. It encourages good minds like Whit to pipe-up and help out, so before you know it the fault is found (exactly as Whit has gone to great lengths to do here).

If you don't take the effort to explain yourself the solution can be harder than pulling teeth.. which won't help anyone.

I hope this optimism doesn't jinx Azale in fixing it now...

[Bill R.]

cps... I would first check again for spark, having somebody help while you ground the coil and the plug electrode and crank it to check for spark, if your not getting spark then i would check the cps, if you are getting spark and you already have fuel pressure then i would check the camshaft sensor which triggers the injectors.

Lowell: Thank you, I do like the car: almost as much as my wife does.

Thank you for being kind with the criticism, I get enough rejection from my BMW right now.

For a little more background: I had it towed to my friend's garage. I live in an apt and my dad's garage already had a disabled vehicle. Because I never heard the pump, I assumed it would be an easy fix with minimal tools--a job that could easily be performed inside my buddy’s garage. Because of the lack of tools, I have been looking for an easy fix, and everyone online is talking about the DME relay, the fuel pump relay, and the crankshaft sensor. When I checked the fuel pump relay, things didn’t add up so that caught my attention.

Now, I am following the bottom-up approach. Using minimal tools, I broke the seal on the fuel rail and gas squirted out all over the place. Fuel in rail and pressurized – check. Plenty of air is coming out of the tailpipe so air must be getting in there. Air – check.

The next tests were performed with no help, while the battery was losing power. I pulled one plug: it was dry and it didn’t look like it was sparking (from inside the car), but the plug wasn’t touching a grounded bolt (which I have been told to do). Then I checked for voltage going into the coil and didn’t get any, but it is possible that when I taped the connections to the frame I wasn’t getting a good connection.

I will check tomorrow with some help but I assume there is no spark and it’s possible that the injectors aren’t pushing fuel. The gas tank has no significant dents .

I say good shape, you may say the car looks great, almost no rust, the interior is in great shape, strong engine, smooth shifting, new timing chain, new tires, new suspension, new steering linkages, and I could perform open-heart surgery in the engine compartment if I had a willing patient.

Stevebuk, I looked for the CPS connector with about as much luck.

Does anyone know what pins in the DME harness are for the CPS? I read they were 78, 79, and 82 was ground. Well, my harness doesn’t even have wiring in socket 79. The way things are going with this job, I’m not surprised.

[azale]

Lowell: the timing chain was replaced as a result of the previous owner’s meticulous care for his car, the fact that it had 190,000 miles, and his vocation as an engineer at ZF Sachs (just for the record, he has an ‘80s Jaguar Vanden Plas in better shape than the 525). He also replaced the main and upper tensioners. Up until now, the car had been driving great, plenty of power, no complaints. I was driving a car when the timing chain skipped a gear and it was . . . obvious, but the car had given me 240,000 miles so I wasn’t as bummed as I am right now. It was actually my dad’s car and his ‘bummedness’ was a different story.

I will inspect the coil packs tonight. Where do I look for the leakage, around the outside or down into the hose that leads to the plug? Do the coils snap off the hose? If one coil leaked, do I need a new DME?

Please accept my pre-apology for the next sentences. I am sorry that I haven’t received my repair manual and therefore am unable to identify certain features on my car. The manual is literally in the mail. 1. Please explain ‘TU.’ 2. I forgot to mention this but last night I was looking at the ‘hot/jump nut’ under the hood that comes from the battery. From there I see a footlong thick red cable going to what looks like a solenoid on the back of the engine (but the solenoid main contact is pointing toward the front bumper and the rest of the unit is toward the firewall). The cable is frayed/split. I assume this isn’t a big problem (yet) because the insulation doesn’t look burnt. I can’t imagine the cable fried because I think the fusible link would bite the bullet first. Let me know.

Genphreak, I also hope your optimism doesn’t jinx me, but it is refreshing.

Bill, thanks for the diagram. I will check for resistance between 16 and 43 tonight but what about the camshaft sensor? Am I checking for resistance between 17 and ground or 17 and 7?

You guys have all been a big help thus far. Thanks.

[Kalevera]

Lol, no worries man. No need for apologies, either. There are no stupid questions around here, so ask away (but a search is always a good idea ).

Someone has a picture of a leaking coil pack. I know I have one, too, but I can't seem to find it right now. The insulation has a caramel color to it. None should be visible when inspecting it. It usually oozes out by the plates. Pull the plastic cover, undo the 2 x 8 mm (or are they 10? I forget) on a pack, use a flat blade screwdriver to disconnect the harness connector, and pull the coil out. While you're at it, inspect the plug holes for oil -- a leaky valve cover gasket will cause oil to seep in there, which has the potential to wreck the lead and coil. Only worry about the leads if they're wet with oil -- just inspect the packs.

"TU" refers to the VaNOS (variable valve timing, german-ified) version of the M50. Mid production run (91, 92) 525s were delivered with the non-vanos version, which has a different head and a few other items.

The solenoid you're seeing is for the starter. It needs a heavy gauge wire, direct from that terminal and from the battery, for all of the obvious reasons.

Good luck!

best, whit

[azale]

I pulled the first two coils off and here’s what I found:
first coil (closest to the front bumper)

second coil

The insulation sure doesn't taste like caramel

I also checked the resistance between DME harness contacts 43 and 16 per Bill R’s diagram: a little more than 500,000 ohms. I found 10,000 ohms between contacts 7 and 17, but I don’t know if that is the proper procedure for testing the camshaft sensor resistance. Is my sensor hosed or is there a better test?

So 'VaNOS m50' and 'm50TU' is the same engine and 'VaNOS m50TU' is redundant, right?

It looked like a starter solenoid but I though the starter was on the front side of the engine. Is the solenoid bolted to the starter?

I would have sent this message last night but my connection is slow as molasses. I use my blackberry as a GPRS cellular modem (unlimited data usage through Tmobile) but for some reason I can’t access google. That’s usually not a big deal but bimmer.info gets ads from some type of google syndication site. My computer downloads all the source code then waits and waits for the ads. But that’s a problem for another message board.

[stevebuk]

I think your coils should be fine, the one nearest the windscreen is generally prone to some rusty marks on its exterior.

I've made great progress with mine, I connected my scope to the ECU socket and both the crankshaft and camshaft sensors were producing pulses. I found the problem was no supply to pins 48 and 54 from the DME main relay, removing its white plastic cover and pressing the actuator allowed me to start the car. The supply to the relay is being switched by the ignition but the coil is open circuit. Off to the stealer tomorrow morning to get a new relay.

Don't know if you've looked at this site but great info on pin outs and wiring diagrams etc.

http://www.carsoft.ru/avtorepair/bmw_e34/E34.html

Steve

[azale]

That's not rust; its coil insulation.

Did you have to remove the intake manifold?

Tell me more about your scope. Does it send power through the sensor while you crank the engine?

[stevebuk]

The coils are potted in a small amount of epoxy, it's quite normal to see a little bit of the yellow resin, if there's breakdown you'll generally see grey streaks, my no 6 cylinder coil had a lot of rust marks on the rubber insulation which I cleaned off.

I'm just using a rather old mains powered scope, I keep meaning to get a more modern hand held one but it works fine and I only seem to use it these days to diagnose the odd car problem.

The scope doesn't provide power it just lets you look at the waveform, the crankshaft and cam sensors produce pulses of around 0.5v (I think) as the engine is cranked which you can see on the scope. If you have a high impedence analogue voltmeter you should also be able to detect the voltage pulses as the engine is cranked - it's really difficult with a digital meter!!

I didn't remove the intake manifold (I've given up trying to locate the cps connector) I decided that I'd measure all the voltages at the ECU plug, so I just unplugged it and connected the scope/multimeter between chasis and the pin I was testing. When I removed the spark plugs and cranked the engine I couldn't smell any petrol so knew that there wasn't any fuel getting to the cylinders - I then did the voltage checks on the ECU plug.

[azale]

What I'm trying to find out, is if you had to pass power to the sensor to test for a pulse. I assumed power was routed to the sensor from the DME (because the diagram only shows two wires). I'm thinking, how can it pulse if I am just testing for resistance? At that point I'm only sending like a milli-milli-amp right? Is that all the power the computer sends through the sensor?

Lowell, I did *not* have any spark when I tested correctly last night.

I have a volt-ohm meter on my Christmas list.
Also, my wife called today to tell me that my computer disks are in. TIS, finally.

[stevebuk]

The Crankshaft and Camshaft sensors don't require power, they're essentially a coil of wire that generates a small voltage as the teeth on the pulley pass them.