Loss of coolant because of a coolant leak is probably the most common cause of engine overheating. Possible leak points include hoses, the radiator, heater core, water pump, thermostat housing, head gasket, freeze plugs, automatic transmission oil cooler, cylinder head(s) and block.

Make a careful visual inspection of the entire cooling system, and then PRESSURE TEST the cooling system and radiator cap. A pressure test will reveal internal leaks such as seepage past the head gasket as well as cracks in the head or block. A good system should hold 12 to 15 psi for 15 minutes or more with no loss in pressure. If it leaks pressure, there is an internal coolant leak (most likely a bad head gasket but possibly also a cracked cylinder or engine block).

It is important to pressure test the radiator cap, too, because a weak cap (or one with too low a pressure rating.

If no leaks - either internal or external, then there are a few possibilities for the overheating. Clogged or dirty radiator passages, clogged radiator hoses, clogged heater hoses, clogged heater core, radiator cooling fans not working.

Did you replace this Camshaft Position Sensor ?
1990 Oldsmobile 88 3.8L FI OHV 6cyl
The Camshaft Position Sensor is located:
Under hood, passenger side, upper engine area,between cylinder heads, mounted behind the powersteering pump reservoir.

Try unplugging the cam sensor and see if it starts. The cam and crank sensor share a voltage reference. If the cam sensor is shorted it will prevent the crank sensor from working also and give you no spark and no injector pulse.

1. At the ignition module, verify that battery voltage is present at pin "P", a Pink/Black wire, during the crank no start.

2. The module grounds through the mounting bracket. Verify that the module is secured to the bracket it is mounted to.

3. Next, probe the Dark Blue/White trace wire at pin "G". As the engine it turned over by hand, the voltage should toggle high and low as the vanes pass in and out of the crankshaft sensor. This signal should toggle every 10 degrees of crankshaft rotation. Typically on an aftermarket module, the voltage will be 5.0 volts on the high and less than 0.20 volts on the low.

4. If OK, do the same test at pin "H", a Light Blue/White wire for the sync signal. Rotate the crankshaft, again this signal voltage should toggle high and low as the vanes pass in and out of the crankshaft sensor. This signal will toggle 3 times per crankshaft rotation. It may toggle in as little as 10 degrees or may require up to 110 degrees of crankshaft rotation.

5. If either of these signals are not as expected, disconnect the Crankshaft Position (CKP) sensor and verify at least 5 volts on both the Dark Blue/White and Light Blue/White wires.

6. If the voltage is now 5 volts, replace the CKP.

7. If the voltage does not increase to 5 volts, check for a short to ground, cut the wire near the Ignition Control Module. At key on, engine off, check for voltage now out of the ICM. If voltage is now present, repair the short to ground.

Could be cable connections, ignition switch, neutral safety switch.

is the car get hot or the gage just stuck

The gas cap usually has a slip system to prevent it from being tightened too tight .I would some how get the old one off and replace it with a new one

When the problem is ongoing, have a helper crank it, while you visually check for spark at the spark plugs. Your local autostore should have a cheap spark tester. You could keep it in your glove box, it won't get hot.

To check for spark, pull a spark plug wire off spark plug. If plug wire is hot, use gloves. Stick spark tester in plug boot, ground metal part of tester to metal part of engine. Engine cranking watch for spark at the tester gap. If you have spark everywhere, check for injector pulse, engine cranking.

Also, check for applicable trouble codes. Some of the national brand autostores will check codes for free. Even if the check engine light isn't on, I always check for codes, anyway. If the autostore tells you, they won't check for codes unless the cel is on, tell them it was on a few seconds ago.

The cause is either a bad crankshaft sensor or a bad ignition control module. The crank sensor fails at a much higher rate than the module.