no fuel no fire at same time

[youstillmyd]

I'm working on a 85 325e BMW and the owner drove it for a little while set it down and later, maybe a month or two, went back to start it, it would not start but cranked over and over. But there was no fuel when the gas line was loosed and also there was no fire from any of the spark plugs and neither was there fire at the coil. What could cause both the fuel and fire to go at the same time. Every now and then it would start and run find. Could the main relay cause this or could it be the computer? Have anyone else experience this problem? And what can I possibly do to find the problem?

[colin93 325is]

the spark plugs probably have carbon deposits built up on them. did you try to replace them?

[csieminski]

When I had my 1986 528e, the fuel pump quit at one point. The car sat at my place of employment for about a week. During this time, the car would crank endlessly but never fired.

An independent mechanic (not my regular mechanic) happened to be nearby and looked at the car for me. He tested for spark and was puzzled by the fact that there was none (at this time no one knew what the problem was yet).

When the car was finally towed to my regular mechanic, he explained that BMW's automatically shut off the spark any time there is a problem in a fuel-delivery/ignition related area.

Your problem is not likely to be the fuel pump, since the car does start and run from time to time. Nevertheless, it seems that your "no spark" issue is a deliberate function of the lack of fuel. Fix the fuel problem and spark should return automatically.

[jeffreyb4me]

I highly recoomend you replace the MAIN & FUEL PUMP Relays, 9 of 10 times this is the cause of symptoms like yours.....................................jeffb

[youstillmyd]

Thanks for all the information!!! It turn out to be the main relay

[bertram25]

Which is the main relay that you are talking about I have the same prob, with a 87 325i convert, it sat for a mounth or two and ran fine when parked and the battery went dead and charged it and no start will crank and if i cross the pins under the relay not in the fues box but the one on the fender well in the center of the three relays i get fuel out of the rail but no spark. thanks in advance bertram25(martin)

[jeffreyb4me]

okay, there are 3 relays under that cover on the l/s wheel house. front to back they are DME Main, Fuel Pump, O2 sensor heater. The Main has 5 terminals, the Fuel pump & O2 heater 4.
when cranking, the big red/white wires from the Main should have B+ and the green/violet from the fuel pump relay will also have B+.
BE CAREFULL doing ANY jumping of terminals unless you're SURE of there function and loads !!

[bertram25]

Here is a twist washed the motor with gunk and it started then ran for a 1/2 hr then did not re start ?

[bertram25]

How do you test the crank sencors

[jeffreyb4me]

A DVOM can really only show continuity of the sensor. The ONLY sure test is with an oscilliscope which is out of the reach of most do-it yourselfer's. If you have fuel pressure while cranking but no spark or injector 'clicking' the 'Reference Sensor' is a possiblity. Is your car auto. trans. or manual ? ? ?

[bertram25]

manual

[KC Ron Carter]

The issue is electrical since it can correct it's self with no intervention.

I would suspect the relays, main, fuel, or o2.

I would be suspect of the OBC relay.

I would be suspect of the ECU.

When running, impacting or thumping the above relays, with the plastic handle of a screw driver will show up a random releasing set of contacts or a crack in the circuit board.

Next under the car examine the leads to the o2 sensor, I have seen it cause this issue, usually it is rain related on the o2 sensor wires.

There is the connector on the WOT switch on the bottom of the throttle body, it get full of leaking coolant.

There are a pair of connectors on the valve cover from the reference and tach sensors.

If the tach is fully functional even when the issue is shutting down the engine, swap the tach and reference sensors on the bell housing and the connectors, they are the same sensor for both.

Swap, or just buy a 027 ecu on E-Bay, they sell for $25 most weeks.

Next and further testing will require, a ETM, and a volt meter.

BMW did a heater hose recall and inserted a valve in the coolant line to preheat the throttle body, and I have seen that valve cause issues in the ECU engine temperature circuit since that is where BMW wired the added valve to.

Sometimes paying a professional mechanic is cheaper.

Later,

[jeffreyb4me]

'RC Ron Carter' has some good points there and there's only so much the 'average joe' can do in the driveway unfortunately without resorting to parts swapping [which I see far too many "professional technicians" also do..........Anyway here were my thoughts prior to 'Rons' feedback.
Many may know this but most don't I think. On manual trans. cars a very common failure involves the clutch of all things. One of the 'ears' on the clutch release bearing snap off. The clutch release will still function on the remaining ear but will feel 'funny'. This broken piece will do one or both of two things. 1] float in the bellhousing until it's caught by the starter teeth on the flywheel and get 'stuck' on top of the 'Reference Sensor' [killing it's output] OR just as often it seems, get jammed between the bellhousing and flywheel and shear off most or all of the 'Reference Pin' that's pressed into the flywheel [the sensor uses this pins different mass to 'see TDC]. There's often just enough of a 'nub' remaining to trigger the DME [most times], other times it won't recking havok with someone unfamiliar with the problem while troulbeshooting. I had one of these towed in to the shop just last week where the customer had replaced EVERY component of the system and it still wouldn't run. With this info in hand I quickly diagnosed the problem saving him $$$ in time someone else might have 'needed'to charge him.
A few comments on 'Ron's' feedback. I think he's confusing an 'Summer Engine Campaign' mod. that was done '87-'88 by BMW in which an 35'C switch was added to the NTC to improve cold running. These switches or the connecting hoses would leak, shorting the switch and causing an overrich condition. The 'Heater Recall' on E30's have NO connection to the DME - they're ONLY connected onto the heater hoses with hoses [no electrics].
While he's correct that the sensors are identicle, they BOTH are for the DME, one is Reference the other is Engine Speed. The Tach siganl is a generated one from the DME to the cluster [you could 'read' it but the info would, for the most part be meaningless].

As "Ron" said, 'paying a pro might be cheaper' it depends on what resources you have available [ a parts car, with GOOD parts?].
If all else seems to have failed, pull out the 'reference sensor' [it's the rearward one underneath]. Turn the engine over slowly by hand looking for that pin [looks like a small block] on the flywheel with a small flashlight. If your SURE it's there, reinstall the sensor and see if it now runs...if so, the ear is broken and it fell to the bottom of the housing when you pulled the sensor out [the magnet in the sensor is what would keep it there]..........beat to you and stay in touch.................jeff b.

[bertram25]

Thinks this fourm is great I have a old Bertram 25 and the help I get there is priceless same here again thanks martin (Bertram 25)

[ckdavis31]

I am having a similiar problem on this topic with my 1988 325i. I am not getting any fire throughout even though it does turn over. I have replaced the coil and the white main relay but it did not help. I swapped (o2 & fuel) the other two relays in that box since they are the same type to see if that made a difference. is there any relays in the main fuse box that can cause it to not fire? I thought the ecu (computer) but a guy at the BMW shop told me it would probably still start if it was the ecu but would run terrible.
This car ran fine until my brother shorted pin 6 or 7 in the connection that looks like the diagnostics connection near the main fuse box (engine plug I think) and firewall. He should have been shorting pin 7 in the diag box to reset the service indicator.