Collected - 1987 Volvo 740 GL

[HillmanImp]

Righto, I can't get this thing to run.

Can anyone with any sort of brain tell me the inevitably obvious stupid thing I'm doing wrong.

Coil seems to be okay when I test it with a multimeter.

Turning the car over, I've rammed a screwdriver in the coil lead and it's not sparking when turning over against this bolt or another bracket attached to the engine.

I've replaced the ignition amplifier as know they cause problems and even tried a different coil and coil lead. 

My question is, am I checking for a spark at the coil correctly? Would I get a spark doing that?

This whole fiasco came about after changing the dizzy cap so you'd think it was something to do with that but at the mo it seems to me that the problem is before the cap, or at least doing the checks I'm doing I can't say it isn't.

Annoyingly I can use my old dizzy cap as the wind blew it off the bin lid and smashed it. 🤦

[captain_70s]

Hall sensor/wiring perhaps? It plugs in under the dizzy cap.

My 740 occasionally loses spark due to the wiring/plug to the hall sensor being fucked (it gets hot and brittle). The hall sensor also lives inside the dizzy and if the seal is leaking and filling the dizzy up with oil (they all do that, sir) it can kill the hall sensor itself.

[Sigmund Fraud]

Just now, captain_70s said:

Hall sensor/wiring perhaps?

My 740 occasionally loses spark due to the wiring/plug to the hall sensor being fucked. The hall sensor also lives in the dizzy and if the seal is leaking and filling the dizzy up with oil (they all do that, sir) it can kill the hall sensor itself.

I was about to type the same - those newfangled electronic Bosch distributors are prone to this.

Also, if you don't already have one of those, get one ! They're an extremely helpful tool, and better than messing around electrocuting yourself...

[HillmanImp]

I'd still get a spark from the coil though wouldn't I though if it was that. 

At the mo, I don't seem to be getting that?

[HillmanImp]

Just reading here:

https://turbobricks.com/index.php?threads/testing-dizzy-hall-sensor.278085/

that the rev counter should bounce a bit if the hall sensor is working. Just turned mine over and it didn't so you might be correct. Would make more sense after arsing about with the dizzy cap. Will go and take a better look.

[Sigmund Fraud]

1 hour ago, HillmanImp said:

I'd still get a spark from the coil though wouldn't I though if it was that. 

At the mo, I don't seem to be getting that?

No you wouldn't, because the coil is supplied by the low tension circuit, so you need the points electronic wizardry to work for it to produce a spark.

[HillmanImp]

Ah, okay so I was chasing rainbows trying for a spark from the coil lead. Will assume that works then.

Not been out to check the hall sensor yet, just been for a bike ride. Will have a rest and try and get to it, as its in a frigging horrible place on these cars.

[HillmanImp]

Ta chaps, it was indeed the hall sensor. Car is now running fine.

However regarding timing, Do I have a vacuum advance on this? I can't see one, if I did where would it be?

[Sigmund Fraud]

No vacuum advance in those, ignition timing is controlled by a rudimentary ECU.

[HillmanImp]

21 hours ago, Sigmund Fraud said:

No vacuum advance in those, ignition timing is controlled by a rudimentary ECU.

That'll be why I couldn't find it then. Ta.  The HBOL looks like it was probably BOLing again.