Volvo 1800ES D-Jetronic MY73

As I mentioned in my introduction, I recently purchased a 1800ES. This car has a smart cosmetic aspect, but technically some points to review.
Here it is :





This car, as most of D-Jet cars, has two relays to pilot fuel pump. There was a third one, recently added according to the clean wires, that was supposed to replace one of the old ones. It was wired on ignition coil, which I think it is a mistake. With this relay the fuel pump had a strange behavior : sometimes the pump run, sometimes not. I think it was a source of problems (and I prefer original state to any modification which is not in line with original definition)

So I removed this recent relay and checked the old ones, which were in good condition. I carefully wired the two Bosch steel relays with original loom (which has not been damaged, hopefully). At position II of the contact key, now the fuel pump runs. But there are two problems :

1 - the fuel pump runs continuously at position II, before starting. It should run for 1 or 2 seconds only. Maybe something makes the ECU believe that the engine is already running ? I discovered also that fusebox (old style conical fuses) has been replaced with a chinese fusebox. But busbars included in old fuse rack are missing, so that additional wires have been added... I managed to find an original fuse box to recover original state. I will receive it in a few days.

2 - the mixture is considerably more rich now than before : the car starts not easily and spark plugs are fouled. I think that fuel pump was running with low current so that flow and pressure were low. Fuel regulator has been tuned in this condition so that now with a well running pump pressure has increased. What do you think about this assumption ? I will check fuel pressure in a few days (I'm waiting for a T 8mm-8mm-6mm to plug a manometer correctly) to check this hypothesis and go back to correct pressure value.

Around these two problems, I tried to check simple thinks according to Djet checklist :
- Trigger contacts seem in good state :



- MAP Sensor has its yellow plug intact ; resistance of primary and secondary coils are ok (84.5 and 307 Ohm)
- Coil primary and secondary resistances are OK (3.3 Ohm and 9000 Ohm)
- Throttle switch is OK and correctly installed now

So, could you help me about points 1 and 2 ? Thank you very much in advance


 

Hi Jean-Pierre,

what a nice snowhite coffin (as we call them in Germany). I start with 3 questions:

1. Does pressure sensor hold vacuum? See my test in checklist and video in compendium.
2. Has someone changed wiring so that fuel pump relay is not operated by ECU but by ignition switch? was sometimes done when ECU failed to control fuel pump.
3. Have you verified that you have correct components? You can check on Bosch website www.bosch-classic.com/de/de/produkte/fah.../?selectedFilters=10 for B20E engine for example

Thank you for your reply. For the moment the coffin stays at the garage... but it should take the road quickly with your help !

So... YES pressure sensor holds vacuum ! I did the test just now. Difficult to build a airproof test device but it holds definitely -0.35 bar for one minute, so it should hold longer.

MAP sensor is 0 280 100 015, it is OK as far as I have read.
ECU not checked yet...

Sorry, other questions will be answered later, I have to leave the place where the car parks for one day and a half.

 

So... I can answer :
1. Does pressure sensor hold vacuum? Yes
3. Bosch numbers check : All components are matching with Bosch number list, except distributor which is for B20F engine, but i think it has no direct link with my problem (Bosch Classic has kindly sent me the advance curves, which are similar)
2. Has someone changed wiring so that fuel pump relay is not operated by ECU but by ignition switch? It seems that it is not the case. I performed several electrical tests to check this point :
a. wire 19 between ECU and connector 85 of fuel pump relay is ok in terms of continuity
b. Voltage between connector 86 and -Bat is Ubat
c. Voltage between connector 85 (wire 19 from ECU) and -Bat is 130 mV always (engine running or stopped) ; my understanding is that it should be almost zero V during one or two seconds, then Ubat (to stop the pump).


 

Hi Jean-Pierre,

there is a pull-up resistor in pin 19. Only when ECU wants fuel pump active pin 19 will show 0V. If it is 130mV all the time it is either another resistor and ground connection or ECU has an issue.

So... Today is a great day, I have driven the ES on 50 km ! Carefully switching off to position 0 as soon as engine stops.
Engine runs well, although a bit with a slightly lean mixture. Spark plugs are coloured white with orange negative electrode. This is a bit surprising for me, as line pressure is set at 2 to 2.1 bar. Maybe my manometer is not accurate enough ? I ordered all the parts to build an accurate one according to Dr-Djet page.

Concerning electrical issue on fuel pump triggering, I will first put back the fuses rack and come back to a full conformity on fuses installation. Then I'll tell you if it influsences something about fuel pump activation.
 

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...
 

Hi Pierre,

congrats for having found the fault !

4.05% CO seems too high. I would drive a bit and then adjust to workshop manual values. At a quick glance I saw 1-2% as normal value.

I received all the parts to build a fuel pressure manometer, as Dr-Djet suggested.
I just have chosen the "cheap" version of reader, without glycerin inside.

So I tested it on the 1800ES. It works fine and is very accurate, either because of construction and thanks to the big diameter of the reader. A great tool, which can be used for any other injection system with small adaptation.

One point on the 1800ES : the fuel pressure is not constant as the engine temperature rises. If I adjust the fuel pressure to 2.1 bar when engine is hot, I am not far from 2.5 bar at engine start around 0°C. What can be the cause of this ?

Hi Pierre,

normaly that means an issue with pressure regulator. In rare cases it could be too little fuel volume from pump or blockage on return line to tank.

I will measure with another fuel pressure regulator.
If the problem remains, it will be an interesting point.

Some information about work done on this car :
- engine oil drain revealed dark oil, sign of excessive enrichment, probably linked with bad electrical connections... 
- fuel pressure is well stabilised when engine is hot, but remains higher when engine is cold (2.3 bar). As a consequence, warm-up phase is a bit erratic. Unfortunately, as fuel pressure regulator is not available in new condition, it is a bit tricky to find a reliable one.
- throttle sensor has been carefully opened :





PCB was dusty (means some risks of erosion), so I carefully cleaned it with a small and soft pencil, some brake cleaner fluid, dried it with low pressure compressed air, then cleaned it again with a electrical contact cleaner and a thin piece of soft paper inside the contacts.
Then I adjusted and checked the right positioning of the sensor to obtain the resistance change when leaving idle position and the 10 resistance changes when accelerating and nothing at decelerating. Everything is ok.

Finally, I replaced the thin foam barrier around the sensor, hoping to improve the sealing of the housing.

This throttle sensor is the first version, right ? Is it the right one for '73 Volvo 1800ES ? Not sure...

...

Hi Pierre,

yes Throttle switch is an early version with scres and soldered wires inside.

Hi Pierre,
you could use an alternative pressure regulator like this one: www.ebay.de/itm/233599329216 or this one: www.ebay.de/itm/272270476505
This cheap item could work, too: www.ebay.de/itm/373722429530?hash=item57...tkp%3ABk9SR_yr-KGtYw

Regards
Norbert