Citroen DS Bosch D-Jetronic Injection Issues ; Help?

[ChasR]

Right, this is not for my car but a friend's car. I have my suspicions that the wiring is iffy (either from a short, wrong connection or a relay going bad), but just to rule a few things out I thought I would ask on here ; someone is bound to have messed with this injection system on here! I'm not sure if he can buy one either!

Anyway, he has a 1973 Citroen DS21 Pallas with a 2.1 EFI engine using Bosch D Jetronic. When he bought the car it ran very well and IMO would have the naysayers thinking it was not all that slow and wheezy, but we suspect it leaked fuel from a number of hoses etc ; the fuel economy was horrific on the car (I think he reckoned it was doing around 15MPG!). After changing the fuel pressure regulator and alot of fuel lines all seems well there.

However the car does now have other issues. When coming to put the car's battery connection on one of the relays 'clicks' ; there are three of them attached to the battery clamp. All of the wires going to the relay are black with some of them being cut, but no shorting from what we can tell ; the terminals on the end are coloured however where they go onto the relays.

When the ignition is turned on the fuel pump kicks in but just whirrs and whirrs and never stops pumping. It did used to turn off before. The car however does start fine.

Of course, the pump not turning off is a cause for concern with the ignition off. I guess what I am going to ask is what issue do you think the car has? I appreciate it's a tricky question to a car which has probably have had him and certainly people before him botching the car (the lead which makes the relay 'click' goes to the battery, which I suspect should actually be an ignition feed).

All ideas welcome. To be more forthcoming have a few pics and a photo of what people call the devil's injection system:

[Deleted]

I would imagine that the fuel pump relay must have some sort of timer circuit that would let the pump run for a couple of seconds while cranking. It also ,most likely will be connected to the oil pressure switch. As long as there is oil pressure,fuel pump will run. Stall engine,no oil pressure,fuel pump should switch off. Maybe check oil pressure switch and wiring?

[kevins]

If it is the same as the lucas copy of d jertonic  my old xjs used the engine computer switches the pump via a relay if it does not recieve an engine run signal fromm the dizzy, which in turn is fed from the inertia switch, the computer packed up switching it on the xjs it sounds like this may be the same. I ended up wiring it directly to the ignition, a better way would be to wire it via a engine run relay and timer relay in parallel which would retain the original functionality.

[vitesseefi]

Not sure about L but on Bosch K-jet the fuel pump relay usually has a connection to the ignition and monitors the pulses from the ignition. No ignition pulses means no pump run. They quite often incorporate a rev limiter which cuts fuel if the revs get too high. It's rather crude...... Gives a rather low rev limit when you use a 4 cylinder relay in your 5 cylinder car too.

Nick

[Tepper]

Following on from what vitesseefi has said, this relay is used on later Bosch systems so might be the same on D-Jet? It's called a tachymetric relay, it's energised initially by the voltage to the starter solenoid and is kept energised by the ignition pulses. Have you got a picture of the relay? If you were worried about the safety side of things it probably wouldn't be too difficult to wire in a tachymetric relay. Sounds like someone's bodged it in the past either way!

[ChasR]

From reading up it appears to be ECU controlled according to the literature, a little like the Lucas equivalent. What drives that part in the the ECU sounds like another matter but the ignition side sounds like a possibility. On the basis a few things have been disturbed I may get him to check the ignition side and the oil pressure switch.

But yes, the wiring is a little iffy!