- If you have a carburetor (seriously?), the carburetor choke may be stuck closed.
The Fix: Repair or replace choke.
- The engine may have mechanical problems.
The Fix: Check compression to determine engine condition.
The ignition timing may be set wrong.
The Fix: Adjust ignition timing.
There may be a fault in the computerized engine control system:.
The Fix:Check engine control systems with a scan tool. Test circuits and repair or replace components as required. (Generally not a DIY job)
The engine may be running too hot.
The Fix: Check and repair cooling system.
The fuel injectors may be stuck partially open.
The Fix: Replace injectors.
- There may be an emission-control device that is not working properly.
There may be some type of ignition problem.
The Fix: Check and replace distributor cap, rotor, ignition wires and spark plugs.
The fuel pressure regulator may be operating at too high of a pressure.
The Fix: Check fuel pressure with a fuel pressure gauge. Replace fuel pressure regulator. (Generally not a DIY job)