Page 1 of 1

Weak spark wont start lightly firing

Posted: Sat Jun 24, 2017 9:33 am
by 201964
My 320i has been sitting for 6 years. Car will lightly fire on turning over but not enough to keep running, I have changed the coil, the leads are about 2k ohm resistance, the rotor and distributor cap are cleaned up. I have read the ignition control unit rarely goes and it checks out for voltage, resistance etc...
Fuel is all present and correct. Any ideas sometimes it back fires which I associated with the weak spark and the fuel igniting late.

Re: Weak spark wont start lightly firing

Posted: Sat Jul 29, 2017 5:55 am
by Skitzy
Does the 320i have a dizzy that can be adjusted?

Re: Weak spark wont start lightly firing

Posted: Sat Jul 29, 2017 9:41 am
by Speedtouch
First off, ensure the spark plugs are clean and set with the correct gap - consider fitting a new set.

Check the inside of the distributor cap for signs of arcing and cracks, also that the carbon brush has sufficient length to make contact with the rotor arm.

Also try spraying some brake or carb cleaner down the throttle body while someone cranks it over. You may have some stale fuel in the tank/injectors which needs drawing through before it will run properly.

Re: Weak spark wont start lightly firing

Posted: Mon Jul 31, 2017 1:04 pm
by 201964
Thanks speedtouch, I have traced the problem to the incorrect setting of the timing for the distributor pulley when the cambelt was changed. This is the old M20B20 engine with the distributor at the side of the engine. No marks on the pulley, it's a visual set up.

Re: Weak spark wont start lightly firing

Posted: Mon Jul 31, 2017 6:22 pm
by Speedtouch
Ah yes, the good old L-Jetronic 320i. :) Chances are, the air-slide valve may be stuck if it's been left sitting, leading to an overly high idle speed:

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