Random but frequent hard/no starts - 93 Elantra

93 Elantra, 5-sp, 1.6 L
Cold starts without complaint every morning.
But in the normal routine of doing short park-then-go trips with several start/shutoff/restarts, say, while doing shopping/errands
around town, the car won't start sometimes...unless it sits...and sits...and sits...for awhile. Without this nap it'll just crank and crank and...well, crank some more. Usually there's a gas smell too. It may be coincidence...or not...that it seems to happen on warm/hot days?
Then, after sitting awhile, when it does eventually start, it trembles for a few seconds, and all is well again.
I can't make the car do this on demand, however. The problem is predictably frequent but not predictably reproduceable.
Appreciate any diagnostic suggestions!
Thanks,
rib
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rib wrote:

My son's '94 Scoupe with the 1.5 had this exact problem. It was due to a defective coolant temperature sensor.
When this sensor dies, the computer thinks the engine is cold and feeds it too much gas when cranking. The car will start fine when you first crank it in the morning but will leave you sitting around town in parking lots for 20-30 minutes until the engine cools sufficiently to start with the rich mixture.
The sensor was located on the thermostat housing on the 1.5 engine.
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You may also be interested in whether you have fuel and spark when cranking.
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On Mon, 08 Aug 2005 17:25:03 -0400, hyundaitech wrote:

Thanks, hyundaitech and Screwtape!
But hyundaitech's reply reminds me that I neglected to mention that while the engine cranks and cranks, exhaust is choking out the tailpipe. When it finally does start, POOF! a big stinky smoke cloud, then once running fine. I'm also pretty sure this engine is burning some oil, having to add a liter after 2-3,000 kms. Uh-oh.
Thanks,
Bob
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Hey Screwtape! The problem turns out to be exactly the same as your son's '94 Scoupe, ie. a defective coolant temperature sensor.
Problem instantly solved!
Thanks!
*** rib
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