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MG MGB Technical - Good spark & fuel but not starting

Hi,

Have been helping a friend with his mg a 73 gt with twin HS's - he has a good spark, jumping 1/4" at each plug on the block. They are fitted in the correct order; however, after a winter lay-up the car won't start even with a spraying of easy start.

Any suggestions before I start to take things apart?

Thanks in Advance.

Iwan
Iwan Jones

If you've got fuel your plugs may be fouled. Clean them. Check the SU dashpots are free, and get as much cranking speed as you can by connecting jump leads from a running car if possible.
c cummins

Are you sure the plug order is correct? If the leads have been off at all, and especially if the car is new to you since it won't start. You have to determine where the rotor is pointing when No.1 cylinder has reached the top of its compression stroke as although this should be about 1 or 2 o'clock it could be in any one of six or eight positions. If you've checked the basics i.e. spark and fuel, then you have to go back to first principles, if you have spark, fuel and air in the right quantities at the right time then it *must* start.

BTW, how did you check fuel? Taking a pipe off a carb isn't enough, you have to check the plugs after cranking. There should be a strong fuel smell but not soaked. If they are soaked it is flooded, but you can usually smell that anyway from the exhaust especially if the car is in a garage. It *will* flood if you crank on full choke and it doesn't start after a few seconds. In that case crank with the choke closed and the throttle fully open until it (hopefully) catches, then release the throttle and half-pull the choke. If there is no fuel smell on the plugs then fuel isn't getting through the carbs, could be float valves stuck flat and little or no fuel in the float chambers - easy to check with HSs. Incidentally, what did the fuel pump do when first turning on the ignition? Should have chattered quite a bit after a long lay-up, but as he may have done that first attempt to start before he called you he may not remember. Even now it should still click several times if left overnight, if it only clicks once then I'd suspect the float valves. A sharp rap on each float lid might clear them. Also if you take the air cleaners off and lift the pistons so you can see the jets, and put a hose on the overflow port and blow gently in to it, if there is fuel in the float chamber and jet it should bubble up out of the jet.
PaulH Solihull

As well as following Paul's advice, check the distributor cap and rotor. These have a tendency to retain moisture and cause the engine to fail to start. RAY
rjm RAY

This thread was discussed on 29/01/2011

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