325e runs GREAT on starting fluid... dies 10 seconds later...

[lovely325eta]

Hi everyone! I've got a head-scratcher for you! (and I PROMISE to post the solution once she's fixed! )

My 1986 325e will start up on starter fluid, idle and rev like a dream, then die after about 10 seconds (once the starter fluid is burned off).

That tells me a few things:

1. Good compression
2. The engine is getting good spark

My next thought: is it fuel-related?

1. both fuel pumps spin when the engine is cranking
2. I disconnected the fuel line to the starter injector, and it fills up a glass with gasoline in just 2-3 seconds

My next thought: is it the computer, relay, or a fuse?

1. I put in a new main relay
2. I put in a new fuel pump relay
3. No blown fuses anywhere
4. I even swapped the Motronic computer above the glove box (0261200027)
5. No obviously disconnected wires, frayed wires, corrosion, etc. Garage-kept car

Brand new, fully-charged Interstate battery.

Pretty good head-scratcher, huh!! My next question - could it be the two crankshaft position sensors? (mine are both on the transmission bell housing). Or maybe a camshaft sensor?

One last thing - the maintenance indicator Green/Yellow/Red lights stay on all the time, even when the key is off, but it has been doing that for years, so I don't think that is related.

Any thoughts would be INCREDIBLY helpful!!

Thank you!!

[richardodn]

So it fires with starting fluid but not without? It is definitely a fuel problem as in it's not getting any or way too much. Are you sure both pumps are working? On the early cars, the in tank pump only provides sufficient pressure for a carb. The external pump is the high pressure pump for the injectors. Since you are getting fuel to the cold start valve, the fuel hoses are correctly attached. Supply connects to the rail and return to the regulator. Reversed lines would prevent fuel from flowing into the rail. A bad regulator would also give you issues. Do you smell fuel at the tailpipe? Get a noid light and verify the injectors are firing. Remember they fire in 2 banks; 1, 3, 5 and 2, 4, 6. Also to eliminate the chance of the cold start valve dumping fuel and flooding the engine, pinch that line off. All the other stuff you've changed out would affect ignition too.

[msservices]

I would check the fuel pressure with a gauge, since you say it fills up a glass but how big is the glass? A small glass I would expect fuel to spray back out of it if pressure is really where it should be, but I have only sprayed injectors that way on an e30, never tried an open hose. Also check for continuity across the cold start injector, and other injectors as well, to make sure there are none open or even worse, shorted, also test those crank/flywheel sensors for continuity as well, do you have access to a Bentley manual?

[superj]

I would change the trans bell housing sensor that applies to firing. I don't remember which one but my 86 did the same thing and once I changed that sensor, the car would run