motorcranks but wont start, has fuel and spark

[tunethtmkII]

i have a 1990 325i that i purchased "as-is". he said it was driving, then got parked for 3 days and wouldnt start, i somewhat trust his word, he is a credited member of r3v and i read through his build thread. i bought it knowing it had spark, but still wouldnt start. so i assumed it would be a simple fuel pump or relay. i checked the pump and all is operating.

so what im left with is a motor that cranks,

has spark

and fuel to the fuel rail.

i did some research and my possible ideas are FPR, CPS or maybe the motor is now flooded?


has any one had similar problems? any ideas?

[Medivh1984]

Good Evening!
I had that exact issue this fall with my 325i Cab E30, parked it to do suspension work for several weeks, very strong battery, confirmed fuel and spark. While it made no sense why it would have failed, check out the Crankshaft Position Sensor:

Pelican Tech Article

On the M20 it routes along the front of the timing belt cover behind the engine fan, and up next to the sensor plug. I took the fan off so I could access it easier, in a little plastic cover (which I subsequently broke...old plastic). If you have the Bentley manual it tells you to conduct a resistance (Ohm) test on the sensor, my manual is not nearby right now, but I believe it's supposed to be 540 +/- 40 Ohms. In the case of my Vert it was Zero, Ziltch....and I compared to my track E30 to make sure I was testing correct and it returned 538.

As soon as I swapped the sensor out, as I had a spare, the car fired up perfect with no issues.

Hopefully that helps before you start digging into bigger jobs...

Most details on the sensor said this was only the issue if the engine would "barley run", but in my case I could turn the engine over for as long as I wanted to hold the key and run the starter, and it would never even sound like it was about go...

[tunethtmkII]

Good Evening!
I had that exact issue this fall with my 325i Cab E30, parked it to do suspension work for several weeks, very strong battery, confirmed fuel and spark. While it made no sense why it would have failed, check out the Crankshaft Position Sensor:

Pelican Tech Article

On the M20 it routes along the front of the timing belt cover behind the engine fan, and up next to the sensor plug. I took the fan off so I could access it easier, in a little plastic cover (which I subsequently broke...old plastic). If you have the Bentley manual it tells you to conduct a resistance (Ohm) test on the sensor, my manual is not nearby right now, but I believe it's supposed to be 540 +/- 40 Ohms. In the case of my Vert it was Zero, Ziltch....and I compared to my track E30 to make sure I was testing correct and it returned 538.

As soon as I swapped the sensor out, as I had a spare, the car fired up perfect with no issues.

Hopefully that helps before you start digging into bigger jobs...

Most details on the sensor said this was only the issue if the engine would "barley run", but in my case I could turn the engine over for as long as I wanted to hold the key and run the starter, and it would never even sound like it was about go...

sounds like what im going through, and that seemed like one possibility. thank you.

[Medivh1984]

No Problem, I still have no clue why the Sensor, which even when removed was perfect looking without a mark...was a dud. This given the entire time since it last ran it was stored inside, very dry time of year, and battery was never disconnected to have the source be a "short" on reconnected the battery.

I can't think of anything that could have occurred to cause the issue...but experience proved that this was my solution :P

Good Luck!

[paperplane94]

If this helps...

The connector is located underneath the intake mani and it plugs into a big plastic wiring harness box.

[seatown88]

have you tried a stomp test?

Attached is a list of checks that jlevie told me to check when I was having no start issues after putting a motor into my pro3 race car, it's a great way to check all of the electrical circuits that are needed for a start to occur. If you have fuel and all of theses tests pass, then there is something weird going on possibly a bad DME.

When I say DME I mean the DME connector on the harness side so it will require the removal of the DME.

[tunethtmkII]

where is the cps located? is it by the bellhousing or by the front of the motor on a 1990 325i?

and is this the correct part?

[paperplane94]

It is located in the front of the engine above the a/c compressor near the waterpump.

It should look just like the pic above except the cylindrical housing will be metal, not plastic.
It should be help in by an allen head screw, and the wire goes around the timing cover to the other side of the engine.

[tunethtmkII]

It is located in the front of the engine above the a/c compressor near the waterpump.

It should look just like the pic above except the cylindrical housing will be metal, not plastic.
It should be help in by an allen head screw, and the wire goes around the timing cover to the other side of the engine.

then plugs in under the intake manifold?

[paperplane94]

then plugs in under the intake manifold?

yes.

just follow the wire from the cps.

[FLG]

Wouldnt have spark or fuel if it was the CPS sensor.

Timing belt isnt broken i assume? Can you check if the injectors are firing?

[tunethtmkII]

Wouldnt have spark or fuel if it was the CPS sensor.

Timing belt isnt broken i assume? Can you check if the injectors are firing?

many people have told me this, however many people have had the same problem and when replacing the cps it was corrected. from what i understand if the cps is bad it might be sending the wrong signal and sparking off time.

whats the proper ohm reading for the injectors?

[603Racing]

Check fuel pressure. Having fuel and having proper fuel pressure are two different things. If you don't have enough pressure your car won't start. You can check injector pulse and fuel pressure for free before you go buying parts.

[Exodus_2pt0]

If you have fuel, spark, and compression then the engine will run assuming the timing is correct. Either your timing is off or you are missing one of the 4 requirements for a running engine.

Fuel
Air
Compression
Spark

Check your fuel pressure as stated above

[tunethtmkII]

so i pilled all the plugs and turned the motor over a couple times to get the extra gas out of the cylinders. then re intalled the plugs and wires. then i installed the new cps and turned the car over. still no start.

now im left with a possible fuel pressure problem?

fpr?

i dont have access to as fuel pressure gauge. is there any other problems that may be occuring with the dme?

what is a stomp test and howd do i go about performing it?