The car doesn’t idle without gas – 1995 Mitsubishi 3000GT

ANSWER : Hi there. The clutch may be worn and slipping causing the engine to stay running as the shifter is put into a gear selection. If the clutch was working, when put into gear and let off the clutch pedal, the vehicle will either move or stall out the engine. Check the slave cylinder and see if the return spring has broken off causing the clutch fork to stay engaged. Also the clutch adjuster cable could be out of adjustment or damaged. If the pedal and hydraulic assembly has no issues, then I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your clutch.

ANSWER : Hi there. It sounds like it either has some bad fuel in the tank and lines or a bad idle air control valve. As the vehicle has sat for a year, the fuel should probably be changed out and disposed of properly. The idle air control valve could be sticking or inoperative completely.

You could try cleaning it with an appropriate cleaner like carburetor cleaner and see if it clears up, but most likely the valve needs to be replaced. "Tune-up" is an outdated phrase that is commonly overused. There are now maintenance schedules for the replacement of wearable items. A tune-up used to consist of adjustments that had to be made to the fuel and ignition systems; however, these adjustments are now made by the engine computer.

Have a certified mechanic, such as one from YourMechanic, perform a pre-purchase vehicle inspection, a car does not idle inspection, and an idle air control valve replacement if needed.

ANSWER : Fuel pumps rely on liquid gasoline for cooling. Consequently, it is recommended to keep the fuel tank at least 1/4 full to prevent the fuel pump from overheating. If the pump is run to the point of being dry, the seal on the impeller can overheat and get damaged. Even if the pump subsequently runs, as you report your does, it cannot develop enough suction to pick up fuel due to the seal damage. That is possibly what has happened in your case but it should be confirmed prior to replacing the fuel pump. In your circumstance the recommended service is fuel pump replacement but if you request that, the responding certified mechanic will do enough tests to confirm that there is no other possible explanation for the failure. There is a quick and direct way to determine if the problem is lack of fuel. Procure a can of "starter fluid" from any department store. Using the material cautiously (it is highly flammable; keep away from flames or sparks), introduce some of the fluid into the intake of the engine while you engage the starter motor. If the vehicle starts and runs briefly, then you know for sure the problem is fuel starvation of course almost undoubtedly caused by the pump failing. Fuel pump replacement can be accomplished in the field, right at your location, if you desire that service.

ANSWER : Hello,
It sounds like your car responds adversely to various loads being placed on the engine such as turning on the AC. This may be a sign of a faulty MAP sensor. The Manifold Absolute Pressure (MAP) sensor senses engine load and generates a signal that is proportional to the amount of vacuum in the intake manifold. The engine computer then uses this information to adjust ignition timing and fuel enrichment. When the engine is working hard, intake vacuum drops as the throttle opens wide. The engine takes in more air, which requires more fuel to keep the air/fuel ratio in balance. When the computer reads a heavy load signal from the [MAP sensor]((https://www.yourmechanic.com/services/manifold-absolute-pressure-sensor-map-sensor-replacement), it adjusts the fuel mixture to slightly more rich than normal so the engine can produce more power. When this does not happen, you may experience an erratic idle as you have described. This may also be caused by other closely related components such as a dirty or failing mass air-flow sensor, a faulty throttle position sensor or potentially a vacuum leak. I would recommend having an expert from YourMechanic come to your location to diagnose and inspect your vehicle.

ANSWER : Hi there. It is possible that the lack of fuel in the tank may be causing the pump to have difficulty picking up the fuel. However, it is more likely that the fuel pump may be damaged, especially if there was no fuel inside the fuel pump or fuel lines. However, it could be something completely different causing your issues, so it’s probably a good idea to have a professional mechanic complete a car is hard to start inspection to isolate the source of this problem.

ANSWER : Hi there. The fact you able to get the idle speed to drop by tapping the gas pedal, lead me to believe the high idle is due to a sticking accelerator cable. Another possibility could be, a faulty throttle body not allowing the throttle to return to the closed position. Proper diagnoses should be performed to avoid unnecessary repairs. I recommend having your vehicles high idle be diagnosed and repaired by a certified technician, such as one from YourMechanic.

ANSWER : Hi there, thanks for writing in about your 1998 Nissan Maxima. You should not try and run your car until it is fixed, or a fire may result. Check to see if the fuel pressure regulator is leaking fuel into the intake vacuum line on top of it by disconnecting vacuum line and see if fuel is in it. Replace the regulator if it is and change out the oil and filter after cranking over the engine to get excess fuel out of the cylinders. If you want to have these issues verified, a certified technician from YourMechanic, can come to your home or office to diagnose the rough idling and stalling issues.

ANSWER : Hello – your symptoms suggest worn piston rings or valve stem seals (smoking), and a possible air leak in the intake, or idle air control valve sticking open (high idle). Both are signs of a higher-mileage engine with significant wear. I recommend an engine inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.