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Syy0628

Help, crank no start problem e36

11 posts in this topic

Hi,

My e36 316iA with m43b16 engine left me stranded on the state highway 1 last Sunday, I was doing 90kph slight downhill when the engine just lost power and rpm drop to 0. I taxied the car to the side of the road and checked the oil and coolant as I thought the engine seized, but both coolant and oil look good.

Next, I pulled the spark plug, and I can see spark going and the spark plugs seem normal with good a bit red-ish color. I tried to start the car, it just cranks and won't catch at all. I jumped the fuel relay and I can get 12V and ground to the fuel pump, but the car still won't start. At that point, I thought I have a bad fuel pump, but when I took the pump off and bench tested it with a spare battery, it pumps fine, enough pressure to shoot gas right onto my face:wacko:. So I changed the inline fuel filter, and it doesn't help either.   I also checked the fuel pump relay coil side pin 85, 86, 30, 87 I am getting 12V at the fuel pump, so 87- fuse - pump circuit is good, and I bench tested the relay, it is working good. Pin30 is getting 12V at all time which is good, I am getting 12V from pin 86 when DME is turned on, but I got a strange 0.02V at PIn 85 and no continuity to chassis ground. I read it somewhere that a bad crank position sensor will stop the coil side of fuel pump relay getting power, so I tested it, and it seems good apart from quite dirty. In addition to that, I cleaned the MAF as well.

Now I have put everything back and it sometimes starts but won't idle, and sometimes won't start at all. I pulled the plugs again, and there is black soot on the plugs?  I was under the impression that I am not getting fuel so no start, but why is there soots on the spark plugs from I trying to start the car? note that when the car first broke down, the spark plugs look good. 

I am out of ideas, please help. as the problem is kind of interment. to conclude the problem above. When first broken down, won't start at all. Then after I took the fuel pump off and put back on, together with a new fuel filter, it won't start but catches sometimes. 

After I tested and cleaned the CPS and MAF it starts but won't idle but will stay at 1500rpm if I give it some gas. However it eventually died even with throttle input, and I discovered spark plugs covered in black soots.

I cleaned the spark plugs, and now it won't start and catch occasionally. 

I think I should do a fuel pressure test, but I don't have the gauges and being a poor uni student, I am not going to tow it to the shop and pay for the repairs. Does anyone in the forum have fuel pressure gauges is kind enough to lend it to me for a few days? 

 

Sorry about the long and unorganized text written in shitty English, thanks in advance for advices and suggestions. 

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It's been a few days , today I installed new spark plugs and  tried to start the car again, it wont idle, but I can get it to run by reving it to around 2000rpm.  and after about 30seconds, I shut it off, and the spark plugs are covered in black powder like soot again. So is it running rich, or is it normal for cold start ? If it is abnormal, what can cause it to run rich? I would think that the fuel pressure regulator is bad? But would that cause the car to cut out at highway speed ? really need help 

Thanks 

Edited by Syy0628

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Stop fiddling and guessing and be careful with the advice given on here. Get it scanned and checked by a professional BMW specialist

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48 minutes ago, *rUstY_nUts* said:

Stop fiddling and guessing and be careful with the advice given on here. Get it scanned and checked by a professional BMW specialist

Thanks for the reply.

I know sometimes the advice given on forum is not always accurate, most advice is based on people's experience. It can be the exact same problem or completely the opposite. Like Brain tumor will cause a headache but you have a headache doesn't really mean you have got a brain tumor. But it is always good to know what other people think about the problem. 

I do not plan to get it checked by a BMW specialist, I got the car for cheap, and I am learning to work on cars on this cheap e36. I have another car that is totally reliable if I have places to be. so I am not in a hurry. 

I have gone through the Bentley manual and find the BMW is quite interesting in design. 

I just hated the fact that tools are expensive in NZ, and there are no places to hire them from.

Edited by Syy0628

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Failed pressure reg generally helps cold start and makes hot start very difficult. Your fuel pressure is at max during starting as there is little to no vacuum acting on the regulator

Black soot is nothing to worry about.

Clamp off the return line to see if it is just low pressure 

Check for air leaks also as its an m43 

the easiest way to tell is beg/borrow/steal a scan set up using ADS interface and a serial port. 

 

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17 hours ago, dirtydoogle said:

Failed pressure reg generally helps cold start and makes hot start very difficult. Your fuel pressure is at max during starting as there is little to no vacuum acting on the regulator

Black soot is nothing to worry about.

Clamp off the return line to see if it is just low pressure 

Check for air leaks also as its an m43 

the easiest way to tell is beg/borrow/steal a scan set up using ADS interface and a serial port. 

 

I bought the fuel testing tool from the link provided by Eagle,  I should be able to diagnoses the problem properly this time. 

What are the common air leak location on a m43 engine, I have checked the all the intake boot before the throttle body, they are good.

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Any gasket on the engine on an m43 will leak :P 

Brake clean or similar around the intake system should help

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1 hour ago, Syy0628 said:

I bought the fuel testing tool from the link provided by Eagle,  I should be able to diagnoses the problem properly this time. 

What are the common air leak location on a m43 engine, I have checked the all the intake boot before the throttle body, they are good.

I would say you wasted $24.99 on that because it can be tested with your finger as far as a non start issue, but not as a prolonged throttle situation. You may need it later for future problems though. Most technicians are capable of checking a non start pressure related issue on these older vehicles by inspection and feel... carry on though.. I'll keep watching

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On 11/23/2017 at 2:42 PM, *rUstY_nUts* said:

I would say you wasted $24.99 on that because it can be tested with your finger as far as a non start issue, but not as a prolonged throttle situation. You may need it later for future problems though. Most technicians are capable of checking a non start pressure related issue on these older vehicles by inspection and feel... carry on though.. I'll keep watching

It took castle parcel 4 working days to finally deliver the fuel pressure testing kit. The Courier didn't even bother to come down the driveway before I call the breach the second time. 

Just like *rUstY_nUts* said, it is low fuel pressure. But a steady 8psi is really weird, as it shows no sign of failure before, and suddenly died but not completely. Anyway, now I got a used fuel pump from pick a part, it is running alright now. thanks everyone for the help. 

One thing to note is that unlike normal Japanese car from the 90s, on BMW e36 m43 engined car, the coil side of fuel pump relay does not get power unless the DME sees all the signals it needs to start the engine(rpm is one of them, from crank position sensor). which means the fuel pump does not prime, nor does it work with the key at On position.  

 

Edited by Syy0628
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