Sparks, fuel, air but no ignition

[ScienceBoy]

So Harry's been out a couple of times since his MOT, where they adjusted the idles as well. However, he will not start now. He's been out a couple of times without issue, but trying him this week and nothing.

We have solenoid click, we have starter motor, we have 12.3v on the battery, we have sparks from three of the plugs (didn't try the one under the filter, but if three are sparking, something some happen), can smell fuel in the exhaust, fuel appears to be pumping through the fuel filter...
But not a single catch when turning the engine over.

Clearly I'll be asking the garage to come around, even if this is coincidental, but wondering if any other bright ideas may be forthcoming?

[Walrus]

Ignition leads in the right place? If they don't line up at the correct time it wont fire...

[ScienceBoy]

They haven't been moved since he was happily being driven around a couple of weeks ago.

[itchyfeet]

What colour are the sparks?
Try chucking a tablespoon of fuel down the carb and see if it fires at all

[ScienceBoy]

White mostly. Or slightly yellow. I had been expecting something bluer. But I checked the coil and the resistances both seemed within spec. I might try the spoon of petrol. I did give it a squirt of wd40 but nothing.

[ScienceBoy]

Fixed!
So tried the spoon of fuel and it kicked off.
Pulled the inlet hose off the carb and turned the engine over to find little pumping, which is when I found a hiss. The hose into the pump must have been letting by. So I cut it back a bit and reattached and tightened the hose clamp as much as poss after sucking the fuel up from the tank (who knew petrol was sweet!!)
I also pulled out the conical carb inlet filter which did have a few white crumbs in there. Cleaned that out, reinserted, reattached hose and tightened up.

And boom. Not literally. Harry roared back to life again. Happy days

[tandemsandy]

Exactly the same thing stopped Vinnie in his tracks a few months ago. Easy job to replace the fuel pipe with one length of pipe from the filter by the tank, all the way to the pump. Just make sure you get the right spec pipe.
Rob

[itchyfeet]

Fixed!
So tried the spoon of fuel and it kicked off.
Pulled the inlet hose off the carb and turned the engine over to find little pumping, which is when I found a hiss. The hose into the pump must have been letting by. So I cut it back a bit and reattached and tightened the hose clamp as much as poss after sucking the fuel up from the tank (who knew petrol was sweet!!)
I also pulled out the conical carb inlet filter which did have a few white crumbs in there. Cleaned that out, reinserted, reattached hose and tightened up.

And boom. Not literally. Harry roared back to life again. Happy days ...thanks

Fixed