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1979 Spitfire 1500 Starts hard when engine is hot


rhjarvis

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I have a 1979 Triumph Spitfire 1500 that always starts right up when the engine is cold but once the engine warms up and I then turn it off, it does not want to start right up. At times it cranks like the battery is on its way out and at other times sounds like lack of gas(vapor lock). Has anybody else ever had this problem and if so, what did you do to fix it?

My model has a electronic ignition with a 45DM4 CEI distributor.  No ballast that I know of, only a ballast resistor wire that I am having a hard time finding.

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Is that an American spec Spittie?

The ballast resistor can be bypassed by using a wire fed from any white wire source. Probbaly best from the ignition switch then you can have a 12v coil if you wish. I left my ballast wire in just bypassing it. The resistive bit will be in the loom and a b*&^%r to get at.

If the car is struggling to start when warm/hot then this suggests that something is suffering from heat-soak. Coils can suffer from this. So can the ballast resistor.

If when cranking and the starter motor is struggling then it is worthwhile checking your battery and starter motor connections and the earth-wire/braid that should earth the engine to the body. The starter motor needs a good set of connections and earth circuit as it will otherwise struggle and slightly dodgy connections caused by loose clamps or bolts will heat locally.

The heat from a hot engine might well cause connections to change from just good enough to fail.

I would go round checking all connections are sound and tightened up. If necessary disconnect connections and give everything a good clean. Obviously do this after disconnecting the battery.

best of luck.

Neil

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The slow cranking might also be a sign that the ignition is too far advanced, and that it is firing before the piston has passed TDC.  This makes that starter fight against an engine that is trying to turn backwards and, hence, crank slowly.  As a test, retard the ignition a few degrees and see if it makes a difference.

As nielnaz says, heat soak is a likely cause.  Those do not look like standard exhaust pipes to me, and I couldn't see a heat shield between the exhaust and the carburettor.  As soon as you turn off the engine, those exhaust pipes will be cooking the carb and vaporising the fuel.

The ballast resistor wire is a white wire connected to your coil.  If you are running electronic ignition, then it is likely that this has been bypassed already and you have a 12V coil, - or did the car come with electronic ignition from the factory?  I'm not familiar with the North American spec cars.

Although heat-soak on the coil is possible, I would put it lower on the list of possibilities, and the ballast resistor itself is almost certainly not the cause of the problem.

Nice tidy engine, by the way :-)

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