325i wont start, looking for suggestions

[rix313]

Hi all,

I an effort to expand my knowledge a bit beyond the M42, an engine I have spent lots of time living with, I decided to buy an E reg 325i as a bit of a project. Long story short it doesn't run and I'm a tad puzzled. Car is running 35 pin Motronic 1.0 ECU.

• I have fuel at the engine although I want to rig up a gauge and check the pressure in the morning.

• When I removed the plugs they were wet so I therefore assume fuel is getting to the cylinder.

• I checked each spark plug against the rocker and there is spark on all 6.

• The Zone wiki flow chart says to check the blue temp sensor, which on a 3.5degreeC day was reading 4500ohms both at the sensor and the ECU. Seems ok to me...

• I did change the cambelt as there was no history but after triple checking my work, all TDC marks line up and the rotor arm sits on cyl1 of the distributor. As the crank pulley has a keyway it all has to be correct.

• As far as I can tell everything is plugged in and sealed.

I did discover the inlet boot was in bad shape, which while I know won't help, shouldn't stop the engine from running entirely?

Furthermore it has coughed a couple of times like it was going to start, but didn't and continues to crank.

TIA

[Brianmoooore]

If all you say above is correct, then it should run.
Blue temp. sensor or wiring O/C won't stop the engine from starting from cold, nor will holes in the inlet boot. Car should start and idle almost normally with the inlet boot completely missing.
Has it run lately? Petrol deteriorates with age.
Does the fuel pump run when you crank it? Take the supply hose off of the fuel rail and put it into a container.
Fuel pressure gauge is a good idea. Can diagnose faulty fuel pump, faulty pump non return valve, leaking fuel line, leaking injectors and faulty fuel pressure regulator.

[rix313]

Thank you Brian. This is why I need a sanity check really. It’s hard to hear the fuel pump running when it cranks but I rigged up a multi meter, it looks like gets power and I also bypassed the relay and tried to start it and still nothing. I shall try just seeing what goes into a container.

Apparently it did run not long ago and I will be getting some fresh fuel inside it too as it was stood for a while.

[Speedtouch]

The early 325i with Motronic 1.0 had two crank position sensors, one buried away inside the gearbox bellhousing:
https://www.e30zone.net/e30wiki/index.p ... tronic_1.0

I would suggest removing the ECU plug and ensuring the CPS terminals have the correct impedance(s):
https://www.e30zone.net/e30wiki/index.p ... tronic_1.0
https://www.e30zone.net/e30wiki/index.p ... ion_Sensor

[Brianmoooore]

The early 325i with Motronic 1.0 had two crank position sensors, one buried away inside the gearbox bellhousing:
https://www.e30zone.net/e30wiki/index.p ... tronic_1.0

I would suggest removing the ECU plug and ensuring the CPS terminals have the correct impedance(s):
https://www.e30zone.net/e30wiki/index.p ... tronic_1.0
https://www.e30zone.net/e30wiki/index.p ... ion_Sensor

I totally missed the bit about it being the early motronic system, in spite of it being clearly stated in the OP. Yes, there are two crank sensors on these early machines, both located in the bell housing. One determines RPM and the other the crank position - the job done by the missing tooth on later systems.
I've only little experience of this early system (never fitted to Tourings), but it's difficult to see how you'd get sparks if either sensor was dud, as the engine wouldn't know how often to fire one, or the timing of #1 plug to start the sequence. It would know the engine is rotating with just one though, so the fuel pump might run.
One of the sensors is triggered by a magnet inserted into the flywheel, and this magnet has been known to fall out.

[Speedtouch]

Just a thought, if it coughs like it's going to start, perhaps try spraying some Easy Start or similar down the throttle body while you crank it over - perhaps it just needs a little coaxing back into life...

I presume you have purged the system of old stale fuel and put some fresh stuff in, along with a new fuel filter?

[DanThe]

If this is a distributor on the side of the block setup id advise to get the timing light out first, easy start sprayed into an engine with the ignition timing out can result in it spraying fire back out of the intake in your direction

[rix313]

I will drain the tank/test the flow when cranking and get some fresh fuel in there afterwards. But yes I did run the pump for quite a while to behind with to purge it. The cough I've decided is maybe just a load of fuel in a cylinder finally igniting.

[Tineca]

Blocked exhaust?

[Blanca]

If this is a distributor on the side of the block setup id advise to get the timing light out first, easy start sprayed into an engine with the ignition timing out can result in it spraying fire back out of the intake in your direction

With side mounted dizzys very easy to get it wrong, hence I did a YouTube video on the subject.



But isn't yours a cam mounted one? Can one still get it 180 out on TDC ?

[Brianmoooore]

AFAIK, no 2.5 ever had the side mounted distributor.
Yoou can't set a cam mounted distributor 180 degrees out. One turn of the crankshaft and it's correct.
Blocked exhaust, enough to stop the engine from starting, would be very unusual on a car without a cat.
I'm waiting to see if fresh fuel does anything. I have a petrol strimmer that absolutely refuses to start on last year's fuel, whether in its own tank, or the can of mix kept for it. Tip the tank up to drain, add new fuel, and it fires up first pull. Will then happily start and run on last year's fuel.

[DanThe]

Ive noticed the same with old petrol in my chainsaw Brian, must be all the nasty plant based rubbish thats put in it nowadays

[Brianmoooore]

Bl**dy ethanol absorbs water from the atmosphere if it gets a chance, which rusts up the rotors of fuel pumps a treat.
Not much of a problem for cars used everyday, but can cause damage to cars parked up for months at a time, and is also a concern to those of us who run truly 'green' cars on the industrial waste product of LPG, where a half tank of petrol may last a year.

[Blanca]

Bl**dy ethanol absorbs water from the atmosphere if it gets a chance, which rusts up the rotors of fuel pumps a treat.
Not much of a problem for cars used everyday, but can cause damage to cars parked up for months at a time, and is also a concern to those of us who run truly 'green' cars on the industrial waste product of LPG, where a half tank of petrol may last a year.

Have that problem with my Eagle SS kit car with dual DelLortos, I sits there for months on end and the 5 lts I put in the tank disappears and all that's left is goo and I have to strip and clean the carbs, again. and they are going to up it from E5 to E10, shit!

[rix313]

So it was shit fuel!! I pumped out the old fuel which was brown and nasty. Fired 20 litres of fresh stuff in and all is good.

[Blanca]

So it was shit fuel!! I pumped out the old fuel which was brown and nasty. Fired 20 litres of fresh stuff in and all is good.

This 5% ethanol (E5) is rubbish, causes a lot of problems when it goes off.

[martauto]

So it was shit fuel!! I pumped out the old fuel which was brown and nasty. Fired 20 litres of fresh stuff in and all is good.

Nice one Rich, silly stuff like this is the last area where you look sometimes.

Mart.