M60 Won't start (Still)

[BIGRED]

Hello all,

I posted in the E34 area and while there has been replies, to this point in time I am still hunting for the source of my troubles. Car is a 94 530it. I have owned it for a short while, it has 148,000 miles on it and I have no paper history.

History
Once purchased I had a rebuilt transmission put in it and a major service. The car ran really nice. I was out and about, floored it and it downshifted as it should have. There was a stumble the check engine light came on ran much rougher and then died. Re-start attempts within minutes of this event at best showed it trying but would not start.

Condition at time of event
1/2 tank of fuel
No blown fuses
Code was thrown Oxygen sensor #1

Tests performed thus far
Checked and swapped Fuel Pump relay - Both appear to be working fine.
Ran pump before regulator - Fuel was coming out
Put pressure tester at tank - 25 psi (with motor cranking)
Pulled pump and ran it using another battery source - Huge difference in liquid flow

Checked voltage at both fuel pump and main relays - The problem seems to point to something in this area or the oxygen sensors.

With the engine cranking at times there is no voltage at the plug to the pump.

Jumping the fuel pump relay socket (ignition on) does nothing. No power to the plug and or the pump does not pump.

There is a green wire with a violet stripe that should be hot but is not. Tracing it around in circles brings me to 2 green wires to which it is joined. The green wires head to the oxygen sensors.

It "feels" like the oxygen sensor has the fuel pump shut down. I did read when cool, they oxygen sensors have no impact on fuel control until it warms up.

I am fairly certain that is I power my fuel pump directly from the battery, the car will start (assuming there isn't some other control o prevent this).

So.....

I am not sure what my problem is.

Any help will relay be appreciated. I live in quite a remote area and no way is there a mechanic around that has BMW experience.


Thanks in advance!
Don

[632 Regal]

Hi Don,

the O2 sensors wont shut the pump off, sounds like a voltage issue from what you wrote. Im guessing the fiuel filters are fresh and with batt voltage your getting upwards #45 lbs pressure. This will zero it down a bit before you ransack the electrical system which runs miles long.

Double check voltage with key on with engine not running, then with direct 12 volts. if both pull the same pressure at the pump measure at the manifold, could be FP regulator or other nonsence.

Zero this in and we can go from there.

[winfred]

if all you get is 25psi of fuel pressure something is screwed, sounds like the pump to me without getting my hands dirty, should shoot over 75 if you pinch the return line when jumping the fp relay 30 is the power 87 is the power out to the pump, connect those two, 85 and 86 are the triggering wires one should go hot with the key and the computer grounds the other to turn on the pump if i remember right, if you have 3 relays 2 4 pins and a 5 pin the 5 pin is the main and the 4s are fp and 02, if it has 2 relays (like a 535) the 4 pin does the 02 and fp, if the fp relay doesn't power up while you are cranking see if you have spark by pulling a coil and sticking a screwdriver in like a plug and hold it about 1/8" from a good ground (you can get zapped if you are a better ground!). the 02 has nothing to do with starting

[632 Regal]

I like good burgers, get that at IHOP?

[BIGRED]

Thanks for the replies.

Knowing it can't be the OS2's is a BIG HELP!

I want to run my tests over one more time to make sure I have done it correctly, however I am almost sure that I have an electrical problem. In one test I pulled the electrical connector to the pump with the engine being cranked, there was no voltage at the plug end.

Is it reasonable to bypass the entire electrical system and power the fuel pump from another battery source and then.

1. Take pressure readings
2. Try to start the car?


OR will I muck up something new?

[winfred]

you can power the fuel pump by jumping 87 to 30 at the relay, with the key on 30 should be hot, if it's not the main relay may be dead, just look at the bottom of the relay for which pin is which #

[BIGRED]

you can power the fuel pump by jumping 87 to 30 at the relay, with the key on 30 should be hot, if it's not the main relay may be dead, just look at the bottom of the relay for which pin is which #

Assuming (I will re-test) that 30 is not hot with the key on. That points to the main relay as the source of the problem for the FP Relay? Is there a way to test the main relay and socket to confirm that is the source of the problem? AND that the source of the problem isn't further upstream, before the main relay?

Thank you for the help!

[Ross]

It sounds like you are jumping the wrong relay. The grn/vio wire that splits into two grn ones is for the O2 sensor heaters.
The fp relay will have a brn/grn wire to term #4(85 on the relay), the O2 relay has brn/blu at that position.
You have checked for spark, right?

[BIGRED]

I have not yet checked the ignition side yet. I am working on diagnosing fuel first. I have 25 psi at the pump and or at times no power to the pump. The question why?

I will check and see where the grn/vio wire goes (to get it fresh in memory)

[winfred]

the main relay gets it's power from the battery, it's 30 should be hot all of the time, the fp and 02 relays get their power from the main relay

[BIGRED]

Great.

So thee battery goes to the main relay and is not feed via the fuse box? Do you know which wires feed the O2 and FP relays.

Thank you

[BIGRED]

Got part of the problem....

Someone moved the relay order around. I had been testing the OS2 relay(brown) and not the FP relay(blue).

My fault for not checking ALL the wire colors, but being comfy with the pin number which I am learning repeats itself.

Yet today I need to check the FP Pressures.

So while I am not home free yet, I am working through it.

Thanks for the help.
Don

[BIGRED]

With a tee line pressure test after the filters and before the regulator I am getting 45 psi with the regulator the engine being turned over and 75 if I jump the relay. Still will not start.

I think it is time to move onto the ignition side of things and see what I find.

As before, I am grateful for any suggestions.

Don

[BIGRED]

Fuel pressure was OK
Had ignition spark
Battery was drained from cranking

Checked it, it was bone dry (looks brand new)
Changed battery it started!!!!!

Checked charge while running it is about 13.6

My guess is that it shorted out causing a shutdown of computer functions and I was DEAD.

If this is not a reasonable conclusion then please let me know.

I can't believe this. Never a sign of battery troubles of any kind!

Don

[e34musician]

How did it all happen? The car just died?

Seems like "weak battery" can create a lot of headaches for E34 owners.

How can I check the battery condition to make sure I have a heathy batt?

[Ross]

It knew you were contemplating running it on soybean oil. Let this be a lesson to you.

[BIGRED]

Ross the BMW is more than 10 feet from the fuel filler on the MB's so it couldn't see me. (shessssh some people are so lame)

[BIGRED]

Well I don't know what to say. I had the battery tested and it proved to be fine. It was a 1 hour recharge and test.

Maybe it is a computer? Any way to test them?

1. I was driving along, kicked it into passing gear.
2. Engine light came on engine sputtered.
3. Engine died, throwing an OS2 sensor code
4. Car towed
5. Checked for fuel flow
6. Checked for juice at relays, fuses and fuel pump
7. Fuel flow quit from pump
8. Pulled pump it worked out of car.
9. Put it back, car won't start
10. Check FP Pressure none
11. Rechecked electrical circuits and took apart wiring harness in engine and E Box
12. Battery was drained by this point so I went to charge it. Charger kept cycling on and off.
13. Popped open the maintenance free caps, battery seemed dry.
13. Put in another battery and car started
14. Assumed battery had a short, tests out OK
15. Going to put the battery back in and expect it to work, never having found a problem.
16 Looking at .357 online, will it penetrate the block?

Thanks
Don


Don