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|All Messages in Thread||Author||Date|
|86 Buic Century won't start.||Michael||11-14-02|
|My mom's Century (86, TBI, 2.5, auto,A/C) won't start. I've done a quick check and found there is no spark or fuel. I was just wondering what the most likely problem was (ECM, crank sensor (although this model doesn't have one), etc.). Any help would be thankful, as I'm a little busy right now to take any length of time working on it.|
|Re: 86 Buic Century won't start.||Sam Watson||11-19-02|
|Try this: There are two wires at the TBI injector(s), one should be "hot" whenever the key is "on", the other goes to the computer which "grounds" it to turn the injector "on". Use a 12 volt test light and check for power at these wires when key is in "run" position. No power means, most likely, that the main power relay isn't closing. If you can ascertain which wire to the TBI should be "hot", but isn't, then you can splice into that wire with a jumper wire and connect the jumper wire to battery + terminal, that way you are back-feeding the components powered up by the main relay. If the car now starts and runs, you'll know you have to replace the relay, or repair the circuits to it.|
|Re: 86 Buic Century won't start.||Rick Herlihy||11-19-02|
Sam gave you good info about the TBI. Have someone listen by the fuel tank when you turn the ignition on. The fuel pump should run for about 2 seconds. If it doesn't the fuse, relay, or pump isn't working.
To check out ignition systems I use a spark plug with an alligator clip soldered to the shell. Be very careful when testing ignition systems you can get a nasty shock. Use a spark plug with the same gap as the under hood sticker to check if your getting a spark from the dist. You can check the coil (if it is seperate) by the wire that goes from the coil to the dist.
If no spark was produced the Ignition coil, pick up coil, or module is propably shot. The official trouble shooting method checks for voltages at various test points but the quickest way to check the HEI is to find the TACH terminal and attach a test light from the TACH to ground and crank the engine. Never ground the TACH terminal directly to ground. If the light goes on and off as the engine is cranking than the module and pick up coil are working and the coil is probably bad. If no light comes on the the problem lies in the 12v feed, if the light is steady is just dims than the module or pick up coil aren't signalling the coil to fire. IMHO if one is gone the other usually will fail soon so I would replace both. On my 86 4.3 TBI the coil and module were less than $50. If the coil failed check the wires,plugs,cap, and rotor too.
If you don't have one pick up a Haynes or Chiltons manual that covers your car. They have a decent trouble shooting and testing section.