startup problems 930 78-3,3

[jeos]

Hello. what pressure to fuel injection nozzles (Cis) open at? and sitting there a check valve in the distributor head? I ask about this when I soon changed many things in vain because of startup problems. so this is the last thing I need to mess with.

Regards john

[RarlyL8]

Cracking pressure is 40PSI.
Fuel system check valves are in the fuel accumulator and front fuel pump.
What symptoms are you having?

[jeos]

It starts badly when it is hot and has been at approx. 60-90 minutes. I have measured the fuel pressure is 6.5 bar,and I've changed check valves (fuel pump) and the fuel accumulator are new,it has new spark plugs new coil new ignition wires and new battery and ignition stand just
and all hoses are tight and new Vur. valve it has also been

Regards john

[JFairman]

Could be the CIS injector(s) are dirty so the pintle is not seating and sealing so the residual fuel pressure is leaking/dripping out of the injector after shutting down.
Thats nothing new and almost all CIS injectors used to do it eventually in the days CIS was used by most european cars because they stay open all the time the motor is running.
The quality of the gas used and the detergent used in it probably has some effect on that.
With the CIS injector staying open carbon would eventually accumulate around the pintle and on the seat which made it so it would leakdown gas intead of holding fuel pressure around 35-40 psi against the accumulator spring loaded diaphram after shutdown.

EFI injectors are immune to this happening because the pintle is constantly opening and closing against the seat so carbon can't build up on the sealing surfaces and they are somewhat self cleaning because of that.

Try some Techron or Seafoam in the gas, they both use naptha as a cleaning agent and it might help clean the injectors.
To diagnose this you can also remove the injectors and insert them into clean plastic water bottles and watch the fuel spray cone come out of them as you push down on the airflow sensor plate. The fuel spray should be a fine even cone shape all the way around with no dribbleing.

No fuel should drip or come out the injectors while the fuel pumps are on and the airflow sensor plate is at rest - engine not running.

After shutting off the fuel pumps put the injectors in clean empty bottles so any leaking down fuel over the next 2 hours will be visable.

[jeos]

It sounds like a good idea

Regards john

[spuggy]

Originally Posted by jeos

Can you separate CIS injector to clean them

No, but you can soak them and back-flush them, there's a good thread or two on this.

Read this thread Blocked Injectors - how to clean? and the threads they reference.

and maybe adjust them??

Flow adjustment can be done on the fuel distributor, but you'd probably be well-advised to start with a set of CIS injectors that were very close on flow rates to start with.

Threads on checking injector flow here too.

Meter head flow adjustment question??

And another one on adjusting the distributor itself - from Alan L? that I can't seem to find right now.