Engine starts, runs for a second or two, then dies??

Post Sat May 17, 2014 12:46 pm

Hi all...I am trying to start my 1990 Tech 2 Sport...its got 1/4 tank of fuel, and a good battery....it fires up, runs for a second or two, and then dies...if i try to fire it again immediately, it just turns over....if i wait 10-20 mins, it will fire again, but then dies just as quickly... the 'Check' light is on...any ideas before i start replacing things?..

Post Sat May 17, 2014 12:52 pm

Check the CPS wiring isn't chafing on the fan. Also check blue temperature sensor.

http://www.e30zone.net/e30zonewiki/inde ... oubleshoot

http://www.e30zone.net/e30zonewiki/inde ... emp_Sensor

Post Sat May 17, 2014 1:30 pm

Speedtouch wrote:Check the CPS wiring isn't chafing on the fan. Also check blue temperature sensor.

http://www.e30zone.net/e30zonewiki/inde ... oubleshoot

http://www.e30zone.net/e30zonewiki/inde ... emp_Sensor

Hi..right, I dont have a multi meter to hand, but I certainly cant hear the buzz of the ICV...(having read the trouble shooting section)..I will get a multi meter and check the blue temp sensor, the coil and the DME...hopefully, it will stop somewhere there!..many thanks

Post Sat May 17, 2014 1:53 pm

First thing I'd be checking is the fuel pump. I suspect it's stalling under cranking voltage.
Give it a head start by pulling out the pump relay (orange relay under the cover by the air filter), identifying pins 30 and 87 of its socket, and linking them together with a short piece of wire. This should make the pump run continuously.

Post Sat May 17, 2014 2:53 pm

Ok, I realised that I CAN hear the IVC buzzing when the ignition is on....I found 2 orange relays with a 3rd black one by the air filter...both had an 87 and a 30...so i bridged both, one at a time...it turns over but doesnt fire at all...

Post Sat May 17, 2014 2:57 pm

I am going to check for a spark ...and i am pretty sure I can NOT hear the fuel pump...and my car is stripped of its interior...so if It was working, I should hear it..

Post Sat May 17, 2014 3:49 pm

Whatever the issue is, it's undoubtably rust related ! Any more pics ?

Post Sat May 17, 2014 5:07 pm

pacerpete wrote:Whatever the issue is, it's undoubtably rust related ! Any more pics ?

Post Sat May 17, 2014 5:09 pm

I have ascertained a spark...so I guess that counts out the CPS...and would leave the fuel pump as prime suspect?...

Post Sat May 17, 2014 6:17 pm

Indeed. Give it a clout with a rubber mallet or similar.

Post Sat May 17, 2014 9:54 pm

Check fuse 11 by replacement before you get too violent with things.
The pump should run ALL the time with the 30 to 87 link in place, even without the ignition switch being on. Without the noise of the engine it should be easily heard.
The second orange relay is for the heaters of a lambda sensor. Unusual (and unnecessary) for a '90 UK car to have a cat.

Post Fri Jun 06, 2014 2:32 pm

Ok, I have checked fuse 11...i have bridged 30-87 again...i can NOT hear the fuel pump at any time...HOWEVER...when i turn the engine over now it fires up like before BUT it fires more strongly...BUT...still cuts out after a second or two and there is no response to the accelerator.....does this STILL point to the fuel pump?...

Post Fri Jun 06, 2014 2:43 pm

Brianmoooore wrote: The pump should run ALL the time with the 30 to 87 link in place, even without the ignition switch being on. Without the noise of the engine it should be easily heard.

If this isn't happening, then that is your problem.
Double check that you are connecting the link properly and all the wiring is OK by pulling the two pin plug off of the fuel pump and connecting a 12 volt bulb to the plug. The bulb should light of, course.
While the bulb is in place, refit the pump relay and crank the engine. The bulb should light when the engine turns, and go out shortly after you release the key.

Post Fri Jun 06, 2014 2:48 pm

Brianmoooore wrote:
Brianmoooore wrote: The pump should run ALL the time with the 30 to 87 link in place, even without the ignition switch being on. Without the noise of the engine it should be easily heard.
If this isn't happening, then that is your problem.
Double check that you are connecting the link properly and all the wiring is OK by pulling the two pin plug off of the fuel pump and connecting a 12 volt bulb to the plug. The bulb should light of, course.
While the bulb is in place, refit the pump relay and crank the engine. The bulb should light when the engine turns, and go out shortly after you release the key.

cheers Brian...I will try that and let you know..

Post Thu Jun 12, 2014 1:42 pm

Ok, I have got a multi meter in order to test the fuel pump ...what goes where on the wiring to the fuel pump?....there is a green wire and a brown wire..

Post Thu Jun 12, 2014 1:50 pm

Is the brown wire the one I attach the positive probe to?...

Post Thu Jun 12, 2014 1:52 pm

Brown is usually negative (earth) on German cars.

Post Thu Jun 12, 2014 1:53 pm

cheers ...lets give it a go

Post Thu Jun 12, 2014 1:56 pm

12 volt bulb NOT meter!

Post Thu Jun 12, 2014 2:40 pm

Right, it does NOT light up a 12v bulb....and when i put the multi-meter to the connection it kept flickering between 0.00-0.01-0.02v....

Post Thu Jun 12, 2014 2:53 pm

Try connecting 12V (from a car battery or charger) directly across the fuel pump contacts, to verify that the pump itself works.

Post Thu Jun 12, 2014 4:46 pm

I have tried a direct feed...the pump does not operate..

...and when I checked the power to the pump with the mulitmeter again it was now showing between 0.03-0.06 v..

Post Thu Jun 12, 2014 4:49 pm

Sounds like your pump may be shorting out, having seized; use a multimeter to measure the resistance across its terminals.

Post Thu Jun 12, 2014 5:02 pm

The meter shows '1' when switched on....and when put across the terminals does not change..

Post Thu Jun 12, 2014 5:25 pm

That indicates infinite resistance, which would suggest that either the brushes or windings on the motor in the fuel pump have failed.

Try giving it a clout with a rubber mallet!

Post Thu Jun 12, 2014 6:23 pm

Right...the more I hit it, the stronger the fire up is each time...and it's lasting longer...but it still cuts out...i will spend the next couple hours and 'gently' try to coax it into life..

Post Thu Jun 12, 2014 8:20 pm

Whoo hoo!...I have been knocking away for the last few hours....and I decided to give it one last go before I pack away for the night....AND..this time, I decided to get on the throttle once it fired...and guess what?...It ROARED into life!...what a sweet sounding beast!...and I reved the nuts off a little bit!..

..its just idling now at about 650 rpm....I am in love again!...and her name is BMW!!! lol..

Many, many thanks for all the help fellas...

Post Thu Jun 12, 2014 10:03 pm

Good to hear that dude; mallet action FTW!

Post Thu Jun 12, 2014 10:18 pm

Speedtouch wrote:Good to hear that dude; mallet action FTW!

Many thanks dude...I am very obliged to yourself and Brian

...i have learned a fair bit and I reckon I saved a fair amount of money ...and on that basis, I have made a donation to the Zone..well worth it! ...just to hear the sweet straight 6 roaring through the West Midlands evening air! lol..

Post Thu Jun 12, 2014 10:35 pm

Nice one.

Post Thu Jun 12, 2014 11:47 pm

The commutator in the motor is wearing through. If the motor happens to stop on a patch where the copper is completely gone and one of the carbon brushes is on the backing plastic, then it will not restart, until the motor shaft turns a bit under the hammer assault.

Post Fri Jun 13, 2014 9:08 am

Cheers Brian..I think as I am going through the car getting it ready for the road I will replace it for peace of mind...