Volvo 1800ES D-Jetronic MY73

Hi Jean-Pierre,

at least prositive prgress !

You can also remove pin 19 from ECU connector. Then fuel pump relais should be inactive and be activated when you put that line on ground. If FPR is still active, you know that is does not come form ECU. If it is only active when you apply ground, then you know that it is ECU. See Download section for a wiring diagram for Mercedes-Benz.

Yes, I understand, great test to do ! Thank you.
I'll do it after Christmas

Although I did not do the test described above by Dr-Djet, I progressed on other items :
- injector #4 seal (the small one) was leaking, so I replaced all
- hose between intake manifold and auxiliary air valve was cut just after hose clamp ; this was the reason of variating idle speed... this is solved now
- ignition distributor was in bad condition and was not the one for B20E engine ; I found the right one and overhauled it so that now dwell is ok, ignition advance is very stable and the engine runs smoother
- fuel pressure regulator was slightly leaking under the lock nut, so I found another one (unfortunately not a new one, which is very rare as you might know) 
- fuel pressure is set to 2.1 bar again
- valve clearance is set properly (0,40 to 0,45 mm at intake and exhaust) and checked in hot engine condition
- spark plugs were not the right ones (too hot index) ; so replaced with Bosch WR5BC
- rubber boots of all connectors are new now ; this is a piece of patience to replace...
- idle speed is set at 900 rpm
 
Now, the car is quite smooth, engine is responsive, a much more pleasant car to drive than one month ago !

Aux air valve seems not to close at 100%, so I plan to change the plunger that I suspect to be a bit lazy with age.

 I keep in mind to check pin 19 test !

 

I just realised that on the starter solenoid there is no white wire. There should be one white wire to thermal time switch and wire 18 from solenoid to ECU.

I'm quite sure wire 18 has been plugged to a permanent + source, which would greatly explain that fuel pump run permanently before cranking..

Another check to do !

Hi Pierre,

if that turns out to be true, you might also have starting enrichment ON all the time.

What a crazy mistake.

Bingo !
Double white wires connector was plugged on +12V on coil... The distance is quite the same to coil and to solenoid, so someone has been confused... since when is it like this ?

Now that this connector is plugged on starter solenoid, fuel pump activates 1 second when key is at position II !
I'm happy with this, as it is a simple resolution. Hopefully, ECU is not faulty. I always incriminate ECU in very last hypothesis. I have taught from my previous job that 98% of ECU coming from warranty exchange are 100% perfect condition. They are very rarely faulty, but often changed because it is so easy for the garage.

Then I measured exhaust gases and the result is : 4.05% CO ; 11.3%  CO2 ; 227 ppm HC ; lambda 0.91
It may be better but it's quite correct for a 1973 car. What's your opinion ?

Driving test show some hesitation just above idle, TPS should have some maintenance...