Volvo 1800ES D-Jetronic MY73

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...

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