I just had the alternator replaced on my 240. The idle was rough before, it sometimes seemed like it wanted to stall, mostly when it was cold. When I got my car back from the shop, the idle seemed to be really low. It runs rough and I am getting really lousy gas mileage, something like 16 mpg. Any suggestions?

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.

All of this suggests bad sensors. I would check the engine codes and try again!

If it stalls when the brake lights come on then the idle is too slow. The high amps of the lights will load down the engine and lowers the idle.

Sometimes that's caused by a vacuum leak near the manifold area.

Sometimes air in the coolant will cause an idle problem. Air will keep the air temp sensor from sending proper info.
Hope this helps.
Sometimes that's caused by a vacuum leak near the manifold area.

Sometimes air in the coolant will cause an idle problem. Air will keep the air temp sensor from sending proper info.
Hope this helps.

Loss of power, but no mention of rough or inability to idle (including stalling). If those additional symptoms are part of the problem, check for a vacuum leak to the intake. Listen for hissing or sucking noises near air hoses. Look for loose, cracked, or broken air hose connections. Check PCV valve...Cheap to replace, could be sticking, then loosen after truck sitting with engine off. A vacuum leak will not give any light indications, and vehicle will seem to run normal when applying gas, but will want to stall or run rough (or want to stall) when at idle or sometimes when taking foot off gas when slowing down.

could be alternator if it doesnt charge your battery your sensors and computor dont get the right voltage and runs rough and then stalls

mcdevito75 here, Sounds like a faulty voltage regulator, it"s 1 unit with the alternator, change the alternator, also the alt. supplies juice to the ignition switch, distributor abd plugs, thus a rough idle due to bad alternator.

Have they checked your TPS sensor as this is the most common cause for rough idles and stalls...

CHeck fuel pump. Check oxygen sensor

leake intake manafold or bad vac line... try warm soapy water on running motor out of a spray bottle to find leak... the reason the censor seemed to hel is that the take time to set them selfs... after set back to square 1 leak in the air side of motor... typical in your car...

Try replacing the ignition control module it is located under the distributor cap Cost is around $30.