What causes a 1995 Buick Riviera to turn over but not start?

Answer 1

There are several causes. It could be a problem with fuel delivery, or something with the ignition system.

There are several tests you can try. Make sure when performing these tests that all accessories are off i.e. Radio, A/C, the automatic lighting system.

A quick way to tell if the problem is Fuel Delivery or Ignition is simple. Crank the car over a few times then go to the rear of the vehicle and smell the tailpipe. If it smells of gas, then the ignition system is not burning the fuel. If it doesn't smell of gas, then the fuel is not reaching the cylinders.

TESTING THE FUEL DELIVERY SYSTEM

First, disconnect the fuel line at a point FORWARD of the fuel filter. You could disconnect it at the front of the filter, or there are 2 lines under the hood connecting to the fuel rails insert the open line into a glass bottle or some sort of receptacle to avoid spray. Once you disconnect the line, turn the key on and see if fuel sprays out. If fuel comes out, your fuel delivery system is working properly. If no fuel is sprayed into your bottle, try the next step.

In a very quiet area, turn the key forward to the ON position. Have someone listen underneath the car or put their ear up to the gas fill with the cap removed. If you hear a brief buzz or humming noise, that is your fuel pump engaging.

If the fuel pump does not engage, have that person listen under the hood when you first turn on the key and listen for a click, if they hear a click, then another click about 3-5 seconds later that is the fuel pump relay engaging.

TESTING THE IGNITION SYSTEM

If the fuel delivery system checks out, then you'll want to see if you car is igniting the fuel.

The most simple test is checking the timing. If you don't know how to use a timing light, I would recommend consulting a mechanic at this time. Once you've checked the timing and you're sure it's ok, test the spark.

Testing spark is very simple. all you need to do is unplug a spark plug wire, plug a screwdriver into the end of it and hold the screwdriver near a ground. Have someone crank the engine and watch for the spark to jump from the screwdriver to the ground. If you see a spark then that cylinder is firing.

If up to this point everything on your car has checked out and still won't start. Pull all your spark plugs and replace them. They could be fouled or the gap could be set to narrow or wide, which would not allow an effective burn of the fuel.

Hope this has been helpful. Good Luck!