I’ve checked everything! Too much fuel.

[RichHawk]

I am seriously at my wits end.
My 1989 325iX e30 will run for 15 seconds then fuel foul out the plugs.
I have disconnected and ohm tested every single part associates with fuel delivery. Twice.
I am looking for someone who has seen this symptom before.
Cold start with clean plugs will fire up, idle decently and then die in about 15 seconds. It won’t restart, the plugs will be wet.
Remove and dry off the plugs, and it will restart and again die in about 15 seconds.

If I disable the fuel pump, I can run on starting fluid until the starting fluid can is empty, way longer than 15 seconds.

Fuel pressure is 42psi entering the fuel rail.
engine vacuum (measured at FPR port) when running is only 15inhg, but when revved above idle goes to 19inhg. The vacuum does not drop when running in starting fluid, making me think the exhaust is not clogged.

I took the injectors out and bench tested them, but haven’t spray pattern tested them.
I also have not hot water tested the engine temperature sensor.
I don’t know what symptoms a bad #6 plug wire pickup sensor would create.

engine compression is 130-135 psi across all cylinders. Leak down is 5-10% through the rings.

Engine temperature sensor disconnected no change. Cold it ohms out correctly
AFM disconnected, no change.

ICM cleaned and it maintains idle.

Timing belt is new, and perfectly lined up.

DME disconnected disassembled and visually checked. No water damage. In fact it looks like it’s brand new not 30 years old.

flashing check engine codes correctly read whatever senso I leave disconnected, but nothing more.
I've seen a video of a diagnostic tool that could read certain things like engine temperature etc. but is that reading the sensor values, or reading what the DME sees as the sensor values?

Help me please. What is causing the immediate rich fouling
Richard in Kansas City.
1989 325iX

[TobyB]

An additional test:

are your injectors pulsing? This is usually tested with something called a
'noid light'- which is simply a light that's energized
when the injector's open.
It's a subjective test- after looking at a few 'normal' cars,
you start to be able to spot an abnormal pattern. In your case,
I'd be looking for the injectors sticking on.

You can also 'scope them- there's a waveform across the injector,
AND a current pattern through a current shunt resistor that help.

That all said, IF the DME is alive and well
(this is usually confirmed with a 'known good' swap)
there aren't a lot of faults that can result in such a gross fuel failure.
The idle maps just don't have that many external scalars. I
WOULD confirm that you're seeing the temperature sensor
at the DME, and that the DME is well grounded.

I'm thinking either your DME's scrambled or something
far more basic (like a massive short in the connector below
the intake) is holding the injectors full open.

t
guesses at things on the internet

[m3clutch]

Quite the pickle. I recently went through my m20. swaped injectors and revamped the ignition system top to bottom. Car ran awful and fouled my plugs instantly. Changed crank sensor, still ran bad. changed my fuel pressure regulator and instantly started and ran smooth. This won't help you, but it's hard to say what's fouling plugs so fast...obviously too much fuel/poor running conditions. Check your CPS. make sure your spark and coil are good. Injectors are probably fine. Maybe you've got a goofy electrical issue at the connector for the injector connectors (under the intake mani, on the side of the head)?

What do you spark plugs look like after you foul them? They all the same?

I hope you figure it out.

[Gregs///M]

Definitely check on the FPR. Double check your CPS and AFM signals with an oscilloscope. Consider swapping your DME with a known good one.

[McGyver]

Sorry OP, sounds like this really sucks! Maybe some of this will help.

1. Did you change anything that resulted in this condition? Did anything happen immediately before this condition started?
2. Are you sure that you have the correct spark plugs and injectors?
3. Are your coil, cap/rotor, and ignition wires good?
4. Have you tested your throttle position switch?

It sounds like your injectors must be stuck open, which doesn't make sense to have all 6 get stuck at the same time. I would start by swapping a known good DME (borrow one to test). Toby has a point about the wiring, you may want to test the injector wiring for faults.

[e30davie]

The ECU doesn't have some oddball chip/tune in it?

[dnguyen1963]

I vote for FPR

[ADEN]

I vote for FPR

+1