Merc Misbehaving Malarky

[dollywobbler]

Hmmmmmm I'd wind the mixture control back to where it was and try it again.......

 

That's an option, but the idle is still a bit on the rich side, so I don't really want to richen it more. This suggests that either I need to actually go weaker still, or that it's running rich the whole time (didn't get to check this during the MOT) due to a duff sensor somewhere.

[dollywobbler]

Reluctant again this morning, but a boot full of throttle saw it catch. Tickover was very low, gradually improving after about 30 seconds to around 700rpm. A picture is emerging of a car with a duff cold start system, and the mixture just richened to allow it to start. Well serviced by a Merc-trained technician my arse! I feel utterly stupid for being fooled by that one. I can see this car being up for sale again before too long. It's still a lovely motor once running, but I've kind of got my hands full of projects at the moment, with much reduced tinkering time. Sadly for the Merc, I'm much more excited about the idea of restoring a 2CV (or two...).

[cort16]

Engine temperature sensor, not sending a signal to the cold start injector? It would explain why they ramped the mixture up right enough.

[Rocket88]

^^^^^^^^^^^^^^^^^^^^^Wot he said. If that's the problem can't be too tricky to replace?

[dollywobbler]

Gawd knows. Fuel pump relay has also been mentioned as a possibility. Worth pulling out and cleaning the connectors I guess. It's a cheap fix if it works!

[Mr_Bo11ox]

doesnt sound very fuel-pump-relay'y to me, if thats playing up you either get petrol or don't, theres not really a middle ground.

[Rocket88]

Engine temperature sender unit, part number 006 545 45 24, green top, right at the back of the engine near the bulkhead. Nothing to do with the temperature sender unit, which is solely to do with cooling. This doohickey apparently calibrates the engine temp, and sends message to lean off or richen fuel as necessary. Might be the cause of your woes.........

[dollywobbler]

Thanks Colc. I'll try and have a look at some point. Currently failing to fit a tow bar to the BX.

[hairnet]

gi oan wi it