Won't start

[TheShark850]

Hey guys , I am back . I haven't touched my 2 8-series in couple years due to being really mad at them for constantly needing things rebuild

Let's start with the one I am hoping to sell first

1992 , manual , 850i
It will not start any more . Last three times it started , the first time the car was media blasted (glass particles) so it was COVERED in fine glass and paint
The paint guy was about 35 miles away , drove it there , no problem
4 Months later , we had some some disagreements , he changed the contract we had so I took it back , it drove fine again home

Parked it in my garage and 6 months later - it will not start . Took the spark plugs out , the spark plug bridge was fused with dirt , like oil grime I guess ?!? Those were new cables and new plugs . All original old school bosch plugs , the good ones . They were dark-ish and I know car wasn't even driven 200 miles with them and as I said , gap was fused with what looked like grime . I cleaned all 12 , best I could , but the car wouldn't start again . Won't even try to start . Just cranks

A year later - today , I removed the gas hose from the fuel filters by the drivers rear tire , they seem to be releasing gas just fine when cranking

Second test - there also seems to be electricity going to the spark plugs , I removed a spark plug on each side and installed a spark plug outside...only thing I noticed is that when it was being cranked , the spark is not constant , like it will spark , then have little pause , maybe half a second to a second , spark again . Both sides . I do not think that is normal

Things that were also changed before this debacle - the injectors , fuel filters (not the pumps) , spark plug cables , spark plugs , manifold gaskets , rebuilt throttle bodies , fan clutch , radiator .

Any ideas guys ? I'd really appreciate it . I bought this car for a daily 6 years ago and I am further from that place than I was when I first bought it and almost 13k into it and still needs about 8 to 10k to be perfect . Not my best buy . Thanks in advance fellas

[TheShark850]

Update - No gas goes to the spark plugs , they are dry . So either the injectors got clogged in less than 200 miles (how and why ?) or the injectors fuse or relay is not working ? or something else ?
I have a 2nd good running 850i that I can interchange parts from all day long , just need to know where to start from , thanks guys

[Timm]

It is possible but unlikely all the injectors are blocked - if the same fuel has been in the car a number of years it will turn into a rubber-eating chemical that can and will attack the fuel system. Streten had the same problem (I think) on a V12 he was restoring. But, it is certainly worth trying to start the car with some starting fluid before you go much further just to check if your diagnosis is correct!

[rjjablo]

Pull and Inspect your Fuel Pumps. Drain All the gas at the same time. Likely they are all gummed up

[TheShark850]

Thanks guys . Any thing regarding the injectors shutting off , relay or otherwise ? Ive had plenty in limp modes in those cars to know that there may be something electronic waiting to go out haha

[Pneill316]

Just a quick thought but have checked the fusible links in the trunk? Had a issue once where it would just crank and not turn over due to one of these fuses being bad. 45 cent later and she started right up. Even if they look fine still replace as they get hairline fractures over time.

[Rickwalk]

Just a quick thought but have checked the fusible links in the trunk? Had a issue once where it would just crank and not turn over due to one of these fuses being bad. 45 cent later and she started right up. Even if they look fine still replace as they get hairline fractures over time.

Car sat for a year. Check both Batteries in addition to the links. I replaced the links with a built in reset switch. Timm's advise should also be heeded. One does not need to be a doctor to have p a t i e n c e with these specimens.

[mbarrett635]

If the car sat for three years, as Timm and rjjablo said, the fuel has turned to varnish and your fuel system is clogged. Keep trying to start it and your fuel pumps will be toast.

You need to drain the fuel tank, clean and inspect the fuel pumps and fuel lines. The injectors might be clogged, but that's the least likely problem in my experience.

[Marc850]

My money is on the fuel pumps, or the two hoses connecting them to the top off the fuel pump assembly. Happened on both my 850i

[TheShark850]

Update: I was able to start it with starting fluid inside the throttle bodies . After the starting fluids were burnt , it will shut off again so we are back to the injectors not turning on to produce gas inside the engine .

1) I changed the 3 computers in the engine compartment , no change (old computers work on my other car)
2) I changed all relays ! Every one of them from trunk and engine compartment - no change (old relays work on my other car)
3) Checked all fuses - all work
4) Removed the gas hoses to see if gas is being pushed by the pumps , yet , they are pumping gas
5) Gas does not reach the spark plugs



it’s something SIMPLE , I just can’t figure it out . It’s something that is not turning on the injectors ?

[TheShark850]

Another update
There is 12v going in the injectors...at this point I am stumped . I’ll try any recommendations

[rjjablo]

Test or Swap you Doughnut sensors, Car will typically run for a bit before shutting down

[TheShark850]

Test or Swap you Doughnut sensors, Car will typically run for a bit before shutting down

What is the doughnut sensors , where are they located ? What are they for ?

I think you mean the sensor that is connected to the spark plug wires , those wires are brand new and worked fine before parking . Even if one side doesn’t work , the other should still work right and start in limp mode ?

I read somewhere about camshaft sensors , different car though , any idea ?

[shogun]

Donut sensor = cylinder identification sensor on ignition cable # 6 and 12. https://www.bimmerforums.com/forum/s...ex-Sensors-M70

M30/M70 ignition system data accdg to Bentley
Coil primary, coil code # 2051118335 terminals 1 (-) and 15 (+) resistance 0.50 ohm, Coil primary, coil code # 20510171101 terminals 1 (-) and 15 (+) resistance 0.37 ohm
Coil secondary, coil code # 2051118335 terminals 15 (+) and 4 (ctr. resistance 6.0 kohm, Coil secondary, coil code # 20510171101 terminals 15 (+) and 4 (ctr. resistance 9.0 kohm
spark plug ends 5.0+/- 10% kohm, shielded plugs 1.0 +/- 20% kohm, spark plug wires 0 ohm (approx.), rotor 1.1 +/- 10% kohm

crankshaft position/rpm sensor: 540+/- 10% ohm

from workshop manual
distributor rotor 1+/-20% kohm, angled/shielded connectors 1+/- 20% kohm, spark plug connectors 5+/- 20% kohm, cylinder identification sender coil resistance at 20 degree C (68F) <1 ohm, pulse sender/crankshaft position sensor coil resistance 540 +/- 10% ohm

[Marc850]

I think you should go up the fuel system lines from the fuel rail to see where the fuel flow stops. If you have fuel to the fuel rails and 12V to the injector then they are clogged.
Disconnect all spark plugs before doing that of course.

But It seems clear that it is not an electrical issue, otherwise you would not be able to run the engine with starting fluid.

[TheShark850]

So , I've done extensive testing . Doesn't look like it's the injectors anymore because 12 volt is going to them and I've replaced the 12 spark plugs with the original new spark plugs the car was supposed to come with

Fuel is going to the spark plugs . I must admit , gasoline , even though it's still flammable , is not as fresh as it probably should be , but not to be able to start at all ? I'd expect rough running , trying to start , especially after kick starting it with starting fluid but not starting at all ? I will not attack the gas just yet . Feels like it's something else

I change the distributor caps with my other 850i , it felt like there was little change in the way it was cranking along with the new spark plugs , but after prolonged cranking , it will sound like the other times .

So gasoline going to the injectors , 12v going to them
Spark is present
Starts with starting fluid but not by itself

Besides changing the gas which I will , anything else I should go for ? I like to have my days on the cars busy , having at least few tests I can perform ?

[Timm]

12V on the injectors doesn't mean they are doing anything. There is a constant 12V supply to all of them and then the other side of the injectors is pulsed to 0V by the DME to get them to fire. You can use a probe to check them - there are quite a few 'flashing light' testers available

[shogun]

we had a similar problem some years back with an M70 parked some years, engine did not start, the old fuel clogged 10 out of 12 fuel injectors completely, they did not open anymore, that stuff was like chewing gum. Changed the fuel injectors from a spare engine in and engine started immy. You could also try to clean the fuel injectors and pulse them with cleaning solution, add new fuel injector filters, o-rings and pintle caps.

[mandd]

What is the actual fuel pressure?? If the pressure is too low it will not start.

The injectors should be pulsed cyclically on and off when cranking, DME controls the ground side.

Mark.

Update: I was able to start it with starting fluid inside the throttle bodies . After the starting fluids were burnt , it will shut off again so we are back to the injectors not turning on to produce gas inside the engine .

1) I changed the 3 computers in the engine compartment , no change (old computers work on my other car)
2) I changed all relays ! Every one of them from trunk and engine compartment - no change (old relays work on my other car)
3) Checked all fuses - all work
4) Removed the gas hoses to see if gas is being pushed by the pumps , yet , they are pumping gas
5) Gas does not reach the spark plugs



it’s something SIMPLE , I just can’t figure it out . It’s something that is not turning on the injectors ?

[e32weis]

What is the actual fuel pressure?? If the pressure is too low it will not start.

The injectors should be pulsed cyclically on and off when cranking, DME controls the ground side.

Mark.

Did you get a chance to figure out what the problem is, or any updates available??