They can be both. Some will quit working completely. Some will work intermittently.
Explain in detail what you are experiencing. We may be of help.
February, 22, 2009 AT 9:09 AM
I no longer think coil packs. I have spark but won't start. So I spray starting fluid in the intake it fires instantly one more shot its running. I drove it home it ran great. Went to start it the next day would not even fire. I took the vaccume hose off the pressure regulator valve it started for couple seconds but dies. Replaced TPS and camshaft sensor. Not sure what next. Thanks for the help don't have much money got laid off.
February, 22, 2009 AT 10:55 AM
Test your fuel pressure.
Fuel pump relay is inside passenger compartment relay center, behind right side of dash.