fuel pump relay again.

[Ian Fife]

I got my information from a Volvo trained mechanic who now runs his own Volvo business,

Ian F

[Offgrid]

Originally Posted by Ian Fife

I got my information from a Volvo trained mechanic who now runs his own Volvo business,

Ian F

You were lucky to find someone who knows about car components. Most so-called mechanics these days seem to be either software engineers, or fitters.

I've taken the covers off the two failed relays, and they are very different ( although they are both green ). The one that failed in the traffic jam has got a wire that has become de-soldered, and the insulation has melted slightly at the end. This ties in with the fact that the case became red hot. I'll resolder it, and see if it works, if so, I'll keep it as a spare. I'll have a look at the wiring diagram, and see if I can work out where the heat came from. Since fitting the replacement, the car seems to be a bit friskier, and the starter disconnection hasn't returned. I'll give it another couple of days before forming a conclusion about that issue.

The reversed functionality of the earlier failed relay will require a bit more research. I'll keep you guys posted when I get round to doing that.

The white relay has arrived, and it appears to be identical externally. The connectors and lugs are all in the same locations. I haven't had the courage to try it yet. I might do that on the saloon, but it doesn't have a back box right now, and the neighbours complain if I start it too often.

[Offgrid]

OK
Here is the definitive answer for a 1990 B200E engine.

Green ( mechanical ) is the correct relay. With it fitted, the pump runs for a couple of seconds on turning the ignition key, and the engine starts.

White ( electronic ) doesn't work. The fuel pump run continuously when the ignition key is turned, and the engine doesn't start.

Apologies to anyone who's opinion I called into question.

[classicswede]

Told you so

The relays do get hot as they are a high load relay and that is why the soldering can let go. As the soldering starts to fail the relay gets hotter

The covers unclip easy enough to look at them. You can sometimes repair them

Stop looking for information in the US as it does not apply to UK cars

[Rversteeg]

The 2 seconds priming function is not in the relay itself, but in the ECU.
The name fuel pump relay is a bit misleading as it is actually a dual relay with a primary one powering the ignition and injection system and a secundary relay powering the fuel pump(s). Quite a crucial relay in the heart of ignition and fual system.

[classicswede]

Originally Posted by Rversteeg

The 2 seconds priming function is not in the relay itsef, but in the ECU.
Th.

Can you show me and the rest of the world where the ecu is

[Rversteeg]

The ECU I am referring to is the LH-computer for the fuel injection system, located just behind the right front wheel arch, near the driver's right foot.