Vehicle: 1991 Dakota S 4x4 with 5.2 liter V8 - Auto trans - 198K miles

This issue started with the engine going into a high idle condition at random intervals. Generally, this could be stopped by a hard application of the throttle. This went on for about two weeks. Yesterday it turned over normally, but refused to start. It is not displaying a check engine light.

I'm sure there are several possible causes like the Idle Air Control Valve or perhaps the Throttle Position Sensor. This is my first Dodge vehicle so I'm at a loss. What is the most likely cause? I have very limited funds so any and all help will be greatly appreciated.

Thank you in advance.

 

Tried cleaning out your MAF sensor? I had a weird idling and running issue with my truck and found a tiny piece of fuzz in there last week

 

Both the MAF sensor and IAC have now been replaced. When it is cold the engine will start and run. If I run it up to normal operating temperature and shut it down it won't start. I guess the next move is the Air Charge/Manifold Temperature Sensor.

 

In the end it was a bad fuel pump. That has been replaced along with the external fuel filter. I still have a rough idle, but I suspect a tuneup will clear that up.

The only other oddity is a "surging" when driving at 35 mph +/- 5 mph. This can be an rpm change of as much as 200 rpm. This is a puzzle yet to be solved.

 

So the "surging" issue has been solved as well. In keeping with the MOPAR reputation for being "picky" the transmission was 1/2 quart low on fluid. The issue went away with an added 1/2 quart. The trans has since been serviced.

 

The high idle issue could be caused by the Idle Air Control Valve (IAC). It controls the engine idle speed, and if it’s sticking or dirty, it might cause problems like this. You can try cleaning it with throttle body cleaner.

Another possibility is the Throttle Position Sensor (TPS). If it’s failing, it can send wrong signals to the computer. You might be able to test it with a multimeter to see if it’s working correctly.

Since it won’t start now, you should also check if the engine is getting fuel and spark. Look at the fuel pump, fuel filter, and spark plugs. If you can hear the fuel pump running when you turn the key, that’s a good sign.

With no check engine light, it might take some trial and error. Start with the IAC and TPS, since those are common causes.

Let us know what you find!