Cranks, Backfires, Won't Start

[Neilskiw]

Greetings,

I'm stumped. Where to look next?

1994 325 IS

It drove into the garage. 2 months later- Cranks a couple seconds and ceases like it wants to spin in reverse. Sort of like the distributor was way out of whack... if it had one. Put in new plugs. Had the injectors cleaned. Tested the crank position sensor. Tried another TPS. Tried 2 different known good DMEs.

Suggestions?

Thanks in advance!

[Eric93se]

Got gas in it? Did it start fine before you worked on it? check over your work.

So the car sat for 2 months, check the battery voltage, should be over 12v when the car is off.

[Neilskiw]

Thanks for the reply, Eric!

Voltage seems plenty. Even tried 2nd Batt on jumpers. The cranking and then ceasing had me questioning voltage also. Occasionally I've gotten it to crank continuously, but then I worry about frying the starter. The fuel isn't that old, but I might drain the dang tank and start over for good measure. The fuel filter is brand new.

One fellow 325 racer suggested "The Car Wash Syndrome". Start, back out, wash, pull in, and next time... no start." Okay then..... how do you fix it?

The car is more of a CARcass. It gets swapped from garage to car trailer when not working on our '92 325 IS race car. Need a bigger shop. Plan is to use it for seat time on track day.

[Eric93se]

No need to dump old gas, just wanted to be sure you were not on E. The fact that it cranks and then stops is odd, could be a loose wire somewhere or possibly a bad ignition switch.

Do the basics, make sure the fuel pump runs (it should only prime for a second when you turn the key). Pull a coil and stuff a spark plug in it and ground the spark plug, crank and check for spark.

[jclausen]

Fuel pressure?

[Neilskiw]

Thanks for the reply, JC. Yes, I have fuel pressure.

I have intercepted the fuel line at the fuel rail and pumped all the gas out of the tank. I'll put it in my Valiant. That sucker will run on moonshine.

I've been looking at the IACV. I have 3. All were stuck, so I cleaned them. 2 wiggled to and fro rather sloppy. I installed a sloppy one before I found the 3rd, tighter valve.

Next step is to fill with fresh fuel, and swap out the IACV. I'll check all 6 coils for spark again, and maybe even check the brand new spark plugs for good measure.

It ran. It had no front bodywork, radiator, serpentine belt, or alternator. But it ran. Just long enough to move it without heating it up. Now it has all those parts and it's scared of what comes next.

[Eric93se]

So the last time it ran was without a radiator.....

[Redchugger]

I had a bad MAF and a loose intake hose and it did the same thing i would check those and maybe check wires and fuses if you havent
i had my car outside overnight and there were rats that crawled in my car and chewed on some wires

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[Dekoninck]

I had an issue with my 325i some months ago. I went home to pick something up, stop the car at my door, went inside and when I tried to turn it on it began backfiring and if I kicked a bit the throttle it would stop. The engine made noises like popcorns and I thought in the worst things possible. Took it to my garage and after coming through the whole world of google I found a video of a guy having the same issue.

Under the intake, there's a conector for the "recirculation of oil" (?), not sure how to say in english. The thing is that it went out of place and the engine was mixing more air than it should.

I am just telling you because it happened out of nothing and maybe, if not the same connector, something could have been pushed out of place when cranking like happened to me.

Not mine but here's a video:

https://www.youtube.com/watch?v=b_PjGlsKBec

Good luck!

[Neilskiw]

Greetings and thanks for all responses.

I went back to basics and am checking everything as Eric suggested. Compression on all 6- Check. Spark on all 6- Check. Fresh 92 octane fuel- Check. New o-rings on the intake manifold- Check. Ohms test the crank position sensor- .52 I had visions of injector pieces dropping down the port and holding open the valve for the piston to collide with on the way up.

Which way should the arrow point on the IACV ?

Again, thanks to all !

[Eric93se]

Did the spark plugs have any gas on them after trying to start the car? No fuel on the plugs, most common is the cam sensor. Unfortunately its a hall effect sensor and it's not easy to test.

[flyfishvt]

Arrow should point towards the intake manifold. I had this issue on my 95 325. In my case the hose from the ICV had popped out of the intake manifold. Created a massive vacuum leak. The plastic clip that holds that tube into the manifold is a well known failure item. Especially when they get 20 years old. Use a light and look down through the middle slot in the intake runners. Use a large screw driver to push that clip/hose into place. If it moves at all when you push it then you might have found your issue.

[Neilskiw]

Greetings!

I thought some really helpful folks (all whom replied) might appreciate hearing the solution.

It was a loose nut behind the wheel. Remember I said it was like the distributor was out of whack? While I was reinstalling the water pump, alternator, and serpentine belt, I removed the air conditioning pulley from the crankshaft... ... ... and never reinstalled the bolts that hold the crank pulley to the crankshaft. So the crank position trigger spun on the shaft and retarded the timing.

Usually I tape a big paper to the windshield and write down every step during the dis-assembly process so as not to be out of order or forgetting bolts. Well I totally blew it this time.

Thanks again!

[Eric93se]

Face palm!