Non Run issue....any ideas....Scratching my head.

[Mrum]

Hi all. My first time on here. I bought a 71 fully restored CSI a few months ago. You might have see it on oldcolonel classics. I also have an E28 M5 (US version) but the CSI is much more fun....never thought I would say that.
Any...rambling. Have the following issue which I am really struggling with.
Last week car died underway. Did not look electrical. But now not sure. The engine turns and fires briefly but will not run on...just dies every time. I have check the following:

Battery Volts Good
Fuel Pump running and pressure at rail - I have even had the fuel pump running straight off the battery so its on all the time and still wont run on. Inerestingly the fuel pump only runs actaually on ignition....I thought it would pressurise the rail in key position 2 rather than 3.
Spark Plug all sparking
Air good.

I am wondering if it is an ECU issue ? I have seen prices of these so would like to explore all avenues.

Any advise VERY warmly received.
Cheers
Mrum

 

[dang]

Starting circuit versus running circuit?

 

[sfdon]

You need either a screwdriver or your hand or a NOID light (Bosch2)
You need to feel or hear or see if your injectors are working while you crank.
In the meantime- make sure your MPS connector and distributor connector are plugged in all the way.

https://www.ebay.co.uk/itm/Kent-Moo...042875&hash=item2ac470497b:g:WCcAAOSwKhFcZET8

 

[sfdon]

There is a board lending library that I maintain where tough to find or expensive parts are loaned out for diagnosing problems including an ecu.
First look for other obvious issues.

 

[adawil2002]

What are you running in your distributor?
Points & Condenser or Pertronix or 123?
How old are the Trigger Points in the bottom of the distributor?

My CSi had the same condition trying to run a Pertronix. The car would run then die, then restart and be fine for 15 or so minutes and die. The Pertronix module would heat up and stop the electronic pulse, cool and be fine, then stop running, etc.

 

[lloyd]

The engine turns and fires briefly but will not run on...just dies every time. I have check the following:

Battery Volts Good
Fuel Pump running and pressure at rail - I have even had the fuel pump running straight off the battery so its on all the time and still wont run on. Inerestingly the fuel pump only runs actaually on ignition....I thought it would pressurise the rail in key position 2 rather than 3.
Spark Plug all sparking
Air good.

I am wondering if it is an ECU issue ? I have seen prices of these so would like to explore all avenues.

If the spark plugs are "sparking," how did you determine this? Did you actually remove the plugs, and if so, were they wet, dry, fouled, etc.? Unless you recently submerged your car, I would place the ecu last on the culprit list.

Having pressure at the fuel rail is good, but the pressure needs to be at 28 psi +/- 2 psi. The fuel pressure regulator found at the middle of the fuel rail is adjustable. But before going there, I would find the manifold pressure sensor unit and check to see if it is holding a vacuum, by attaching a suitable tube and sucking on it. No vacuum = no running. https://e9coupe.com/forum/threads/pressure-sensor.18005/

http://e9-driven.com/Public/Library/BMW-E9-Manual/pages/en/13.html#refertoc
http://e9-driven.com/Public/Library/BMW-E9-Manual/pages/en/12.html#refertoc

Fuel pressure regulator:

Manifold pressure sensor is on the right:

 

[aearch]

WAY BEYOND MY EXPERIENCE
yet it dors sound like a distributer issue runs then just dies
out of nowhere

 

[3nsahalee]

Check and clean all grounds. There’s a grounds cluster behind the battery that’s ez to overlook that’s given me same-ish troubles in the past.

 

[Mrum]

Morning All....wow what a great response. Thanks very much for all the gems of info. I will collate all later today and make a start this evening. I will revert on findings.
THANKS !!!!
Mrum

 

[Mrum]

If the spark plugs are "sparking," how did you determine this? Did you actually remove the plugs, and if so, were they wet, dry, fouled, etc.? Unless you recently submerged your car, I would place the ecu last on the culprit list.

Having pressure at the fuel rail is good, but the pressure needs to be at 28 psi +/- 2 psi. The fuel pressure regulator found at the middle of the fuel rail is adjustable. But before going there, I would find the manifold pressure sensor unit and check to see if it is holding a vacuum, by attaching a suitable tube and sucking on it. No vacuum = no running. https://e9coupe.com/forum/threads/pressure-sensor.18005/

http://e9-driven.com/Public/Library/BMW-E9-Manual/pages/en/13.html#refertoc
http://e9-driven.com/Public/Library/BMW-E9-Manual/pages/en/12.html#refertoc

Fuel pressure regulator:

Manifold pressure sensor is on the right:

Awesome thanks !!! Yep removed plugs and grounded...good spark. Can I trick the Manifold Fuel Pressure Sensor by jumping the connections ? Quick way to prove ?
Mrum

 

[dang]

I made my comment while up to my elbows in grease earlier... I meant to ask, does it start and then stop immediately after letting go of the key or does it run for a few seconds before dying? What's the chances of the ballast resister being faulty? Does it have one?

 

[Mrum]

Hi....With the key in stat position 3 the engine does fire but then dies immediately after releasing key. It does not really run on. I can't help think it's something simple. I will check on the resistor...thanks

 

[Stevehose]

Faulty ignition switch?

Hi....With the key in stat position 3 the engine does fire but then dies immediately after releasing key. It does not really run on. I can't help think it's something simple. I will check on the resistor...thanks

 

[sfdon]

Run a direct wire from battery positive to big lug on coil - if switch is bad this will bypass switch.
disconnect QUICKLY if engine now runs.

 

[Mrum]

Hi..thanks for advice..sorry to sound stupid here - which coil ?

 

[E9madada]

The coil that supplies HT lead to distributor.
Where abouts in the UK are you?

 

[Mrum]

Gotcha...I am in Romsey, Hampshire. Right on South coast near Southampton.