BMW Bosch Fuel Injection System Trouble-Shooting Guide

SYMPTOM:	PROBABLE CAUSE:
No cold start	Fuel-pump fault or clogged fuel-filter
	Additional air-valve not opening correctly
	Start-valve not opening correctly
	Leak in fuel system
	Throttle-valve plate not opening correctly
	Temp.-sensor fault
	Diode-relay fault
Poor hot start	As above then:
	Leaking / faulty injector
	Heat/time switch fault
Poor idle	Baffle-plate stop wrongly adjusted
	Leak in Vacuum-system
	Fuel-filter clogged
	Mixture-adjustment incorrect
Backfire from engine	Weak fuel mixture
	Fuel pressure too low
	Starter-valve leaking
Engine runs on after shut-off	Leaking / faulty injector
	Stiff/stuck baffle-plate
	Stiff/stuck control-plunger
Excessive fuel consumption	Control pressure too low
	Starter-valve leaking
	Leak in fuel-system
	Fuel mixture too rich
	Heat/time switch fault
Idle-speed too high	Control pressure incorrect
	Additional air-valve stuck open
	Baffle-plate stop wrongly adjusted

Detailed maintenance guide / diagrams in this post [L-Jetronic] - https://www.beemerlab.org/2020/03/bmw-bosch-l-jetronic-fuel-injection.html

Bosch K-Jetronic injection-system overview / diagram here - https://www.beemerlab.org/2019/11/e21e12e28-bosch-k-jetronic-fuel.html

Bosch L-Jetronic injection-system overview / diagram here - https://www.beemerlab.org/2019/11/e30e28e34-bosch-l-jetronic-fuel.html