1995 Ford Contour starting problem

First of all, most engine's crank slowly in super cold weather. That's nothing to worry about. If your battery cables show signs of corrosion and your alternator shows signs of failure, then the first thing you should do is have these issues addressed. Because it doesn't make much sense doing further tests because you won't get accurate results.

Once you fix these and if you have the same problems, check for bad gas next. If gas is good, check fuel pressure, clogged filter and leaking fuel pressure regulator.

Time for a new battery and generator. With a shorted diode, you lose 2/3 of the generator's capacity. That means you might be getting only 25 - 30 amps. It takes a good 25 amps just to run the fuel pump, ignition system, and a pair of head lights and the running lights. That leaves nothing left over to recharge the battery. On longer trips the battery may charge enough to start the engine once more.

When corrosion forms around the battery posts, it is about to fail. Over time the lead flakes off the plates and collects on the bottom of the case. When it builds up high enough, that cell will become shorted. Also, when the lead flakes off, that leaves less material to absorb the electrons coming in. The plates and acid heat up faster. The acid starts to bubble, and those bubbles help the acid reach the posts where it seeps through and forms the corrosion. Once that happens you can expect the battery to fail within about six months.

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