Vehicle when started runs rough and will not idle....excessive fuel odour....battery has been replaced....computer diagnostic hand held machine was used to find problem but shows no reading....the computer diagnostic worked on another vehicle.....new computer was installed...but did not fix the problem...the other issue was that the battery fuse was burnt out and replaced....any ideas....

A 1997 7.3 diesel engine that starts, idles rough, and then dies within a minute can be caused by a variety of issues. Here are a few things to check:

1. Fuel system: The fuel system is a common cause of this issue. Check the fuel filter, fuel pump, fuel lines, and injectors for any signs of blockages or damage. If any of these components are faulty, they can prevent the engine from receiving sufficient fuel and cause it to stall.
2. Glow plugs: Glow plugs are used to heat the combustion chamber in diesel engines to aid in cold starting. If the glow plugs are not functioning properly, it can cause rough idle and stalling. Check the glow plug relay and individual glow plugs for proper functioning.
3. Air intake: A clogged air filter or intake system can restrict air flow to the engine, causing it to run poorly and stall. Check the air filter and air intake system for any signs of blockages.
4. Electrical system: A faulty battery, alternator, or starter can cause the engine to stall. Check the battery voltage, alternator output, and starter function to ensure that they are all working properly.
5. Sensors: Faulty sensors, such as the crankshaft position sensor, can cause the engine to stall. Check the sensors for proper function and replace any that are faulty.

If none of these issues seem to be the cause of the problem, it may be necessary to take the vehicle to a qualified mechanic for a diagnostic inspection to determine the underlying issue.

Hi. This issue requires further diagnostics. How many miles are on this vehicle? When was the last tune up? Is the oil changed on time and is it full and free of sludge? I recommend pulling the spark plugs first. They can tell you a lot. You may want to run a compression test. Rough idle and excessive fuel consumption can be caused by poor compression, faulty spark plug/s, bad fuel injector or clogged CAT. There are other things too but it would be better if you start performing diagnostics. This engine has a timing chain. I doubt it jumped time. Let me know if you have more questions. Good Luck.

Car idle is rough Inspection Service & Cost A rough idling engine can be caused by a number of issues, some of them are serious while others tend to be minor, but the symptoms remain pretty much the same. The car will feel rough and bouncy when the engine is running. The car will also idle below its regular speed, display inconsistent RPMs and may produce a shaking, skipping or slipping sound when the vehicle is running.
While a rough idling engine may seem to be a simple inconvenience it often indicates a deeper problem within the engine. The vehicle should be inspected and repaired as soon as possible because small problems have a way of turning into expensive repairs. How this system works: The idle speed of an engine is basically the rotational speed the engine runs on when it is un-coupled from the drivetrain and the throttle pedal is not being depressed. The idle speed is measured in the revolutions per minute of the crankshaft.
When an engine is running at idle speed it generates enough power to smoothly operate equipment such as the water pump, alternator, and power steering but not enough power to move the vehicle itself. A passenger car will usually idle between 600 RPMs and 1000 RPMs. A properly functioning idle should run smoothly without skipping or slipping. Common reasons for this to happen:

• Dirty Fuel Injectors: The fuel injection system injects fuel into the cylinders, which creates a mix of air, and fuel to ignite and burn. Fuel injectors have tiny nozzles to spray the fuel into the cylinder and they can become clogged over time. clogged or failing fuel injector creates a lack of fuel in the vehicle's engine. This can cause a rough idle, it can also cause symptoms such as slow acceleration or the car not feeling as if it has enough power. If the problem is addressed early, it is possible to clean the injectors, which will restore them to full function. If this condition is not addressed in a timely manner the injectors will need to be replaced. Incorrect Idle Speed: While the average idle speed falls between 600 to 1,000 RPMs, if your vehicle is experiencing a rough idle it could be due to an incorrect idle speed setting. A trained mechanic can easily adjust the idle speed, and it should stay at the proper speed. If an adjusted idle speed becomes inconsistent or changes at random intervals there may be a bigger problem that needs to be explored. Vacuum Leak: If the vacuum system has a leak, it can seriously affect the ability of the vehicle's computer to regulate the air to fuel ratio. This can lead to a rough idle and if the problem is not addressed the car may experience slow acceleration and a lack of power. Vacuum leaks should be inspected and repaired immediately. Incorrectly Installed or Damaged Plugs: Spark plugs are responsible for creating the spark that allows the vehicle to burn fuel. If spark plugs are improperly installed or malfunctioning, the idle speed can be affected. The vehicle's engine may vibrate or there may be slipping or straining sounds coming from the engine. Defective or Clogged Fuel Pump: A rough idle can be related to fuel delivery issues. The fuel pump, which is responsible for pulling fuel from the gas tank to the fuel injectors, can become clogged or defective. If this happens the engine will not get enough fuel, which can cause a rough idle, sputtering, stalling and even slow acceleration. Clogged Fuel Filter: A clogged fuel filter can cause similar problems. The job of the fuel filter is to screen out contaminants in the fuel, over time it will become clogged and need to be replaced. A rough idle is one symptom of a clogged fuel filter. Failing Electrical Components: A problem or failure in the ignition system or various electronic components can cause a rough idle. If this is the case, the problem will usually get worse as RPMs increase. Common culprits include the ignition control module, plug wires, coils, and spark plugs. Defective Airflow Sensor: A defective airflow sensor can be responsible for a rough idle. A mass airflow sensor detects the amount of air coming into the fuel injection system and sends that information to the vehicle's computer. The computer uses that data to deliver the proper amount of fuel to the air in the vehicle. Over time these sensors can malfunction or become dirty. One of the first symptoms of a malfunctioning airflow sensor is a rough idle. The car may also accelerate slowly and even stutter or stall as the problem progresses. Dirty Oxygen Sensor: Oxygen sensors measure how rich or lean the gases are as they exit the combustion chamber. Depending on the results, the amount of fuel entering the engine is adjusted by the vehicle computer. The ultimate goal is to maintain an ideal mixture that produces the lowest emissions. A dirty or failing oxygen sensor will usually trigger the check engine light and can lead to a rough idle, lower fuel efficiency and failed emission test.

If your vehicle is fuel injected I would say you have a blown fuel regulator. This would cause excess fuel into the cylinders (flooding) causing a miss and coughing and also blow fuel into the air breather. If will also cause the vehicle to run poorly and could cause the vehicle to stall. Also to much fuel on startup can flood the cylinders and cause the vehicle to no start.

1998 1999 Dodge Durango Service Repair Workshop Manual Download Visit the on-line store, known as reliable-store, they have the repair manuals. I'm sure you will get the solution of your problem.

Hi there:
Black smoke is caused by excess fuel that has entered the cylinder area and cannot be burned completely. Another term for excess fuel is "running rich." Poor fuel mileage is also a common complaint when black smoke comes out of the tailpipe. Black smoke out the tailpipe is the least cause for alarm. Excess fuel will usually effect engine performance, reduce fuel economy, and produce a fuel odor.

How did the fuel get into the cylinder in the first place? Some of the causes of excess fuel are a carburetor that is out of adjustment, a faulty fuel pump, a leaky fuel injector, or a faulty engine computer or computer sensor. If black smoke is present, check the engine oil as in the white smoke example to make sure excess fuel has not contaminated it. Do not start the engine if a heavy, raw fuel smell can be detected in the engine oil. Call your mechanic and advise him of what you have found.

Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

Change your oxygen sensors - they're responsible for feedback that the computer uses to determine the air/fuel mixture. They usually are good for about 60k miles and then start to go downhill. When they get to a point that the computer won't trust them, it ignores them and runs on preprogrammed fuel maps that run excessively rich (too much fuel) to safeguard the engine. You've probably seen a decrease in fuel mileage as well. And the O2 sensors have to be up around 900 degrees before they'll work - the car ignores them until then. That's why you run fine after a cold start but run rough once the car is warmed up.

The O2 sensors you want to change are in the exhaust system between the engine and catalytic converters (the "pre-cat" sensors). There are O2 sensors after the cats as well, but those are used comparatively to determine how well the cats are functioning. The primaries are the ones used for fuel mixture. If it's been this way for a few weeks or so, I'd put new spark plugs in as well - rich fuel conditions can foul them and contribute to the rough running.

I would double check for any air leaks. Replace fuel filter. You will also need to reset computer after new parts are installed. This can be done with a hand-held scanner or diagnostic scanner

it could be an o2 sensor. it could also just need a tune up

Came across a fault similar to this a few years ago and it turned out to be the wires going into the distributor had become dry and brittle due to engine heat.Excessive resistance in the wires made vehicle hard to start and caused problems when accelerating hard.