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MG Midget and Sprite Technical - Won't start

ok. So drove my car (newly rebuilt 1275 midget) to the MOT station. Ran wonderfully.
Never ran again. Won't start.
Fires using easy start or thimble of fuel trick. So ignition ok.
Checked the hif44 carb. Receiving fuel from pump. Fuel in float bowl. Needle valve clear. Jet clear.
Only thing I notice is that the jet is about 3mm above the bridge.
Check it out and it seems to have come free of the plastic piece that attaches it to the bimetallic strip. Push it back in. Still no firing.
Question: should the jet be more firmly located in the plastic mounting. Have ordered a new jet in case.
Any other ideas.
T Dafforn

I think there is a moulded slot that the jet sits in to be restained from movement (ISTR a pair of rings moulded round the jet body that the bi-metal spring sits between)

The spring must be firmly screwed down using the heavy duty spring beneath the screw head, there's not a clip though the spring stops sideways moving of the jet tube when it's in its mounting

The mixture adjustment relies on the slot making the jet rise or fall under the influence of the screw on the side of the float chamber

Have you had the HIF apart or did you buy it and use it untested?

Its a good idea to fit a new float chamber gasket when you work inside the carb too, they stretch and go out of round which makes them prone to leaking
bill l

the jet should be held rigid in the bimetallic strip.
dominic clancy

Ok so think I have pretty much got it sorted. The jet had failed in 2 places. Firstly the plastic housing in which the metal part of the jet is an interference fit had come adrift (interference fit no more). Also the plastic housing has an external collar which prevents the jet moving too far into the jet bearing. Again this is an interference fit on the plastic housing and yes, you guessed it, it was no longer a tight fit and had slipped. Fitted a new jet and then some tweaking and she fired up.
Big question is, what happen to the jet assembly. Old age?
T Dafforn

Dave O'Neill 2

Hmmm. Could be..
I was all very odd as you would need quite a lot of force to do the damage that had been done to the jet. Given that it also happened very suddenly, all very strange.
T Dafforn

This thread was discussed between 20/12/2014 and 26/12/2014

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