Lots to consider with frequently stalling truck
I hope you can solve my problem. I have a 1994 Dodge Dakota with 190,000 miles on it. The engine has never given me a problem until recently. It starts great and, at the beginning of each drive, runs nice and smooth. But, for some reason, after driving about 10-15 miles, it stalls. It usually happens when I stop at a stop sign or when I let my foot off of the accelerator going down a hill. The panel lights up. I can crank the engine, but nothing happens. It’s as if the engine is getting no fuel or power. If I let the truck sit for about a minute or two, it will start back up, and away I go. I have taken it to two garages, but they cannot find anything wrong. I have tried using two tanks of high-octane gas and fuel injector cleaner, but nothing’s changed. What is happening? — Les L.
Your Dakota is intermittently losing spark, fuel injector commands, or fuel pressure, or the controlling computer is issuing erroneous commands to important actuators. I’ll assume your shops have checked for trouble codes and came up with none.
We can at least narrow this down with the following checks: Purchase an OTC 6589 spark tester ($10-12) or something similar. Next time the truck quits, run around front, remove a spark plug wire from an easy plug, attach the end to the tester, clip the tester to engine metal, and look for spark to jump the tool as you or a helper cranks the engine. This is a pass-fail test.
Moving quickly, next use a long slender screwdriver as a stethoscope, placing the tip against one of the fuel injectors and the handle to your ear as a helper cranks the engine. Stay clear of hot moving parts! Practice this under normal conditions so you know what to listen for. It’s possible you could be losing both spark and injectors, which would steer us toward the crankshaft position sensor as a prime suspect.
Also, learn the normal sound of your fuel pump (should be a smooth consistent hum) with key on and engine off. Remove the fuel cap or place your ear to the truck bed/fender as needed. It will run only 2 seconds, then cancel, unless continued cranking or another key-on cycle occurs.
If you’re losing spark, possible culprits are a faulty crankshaft sensor, ignition module, ignition coil, and perhaps an intermittent wiring connection. No injector drive (operating commands) could be a faulty cam or crankshaft sensor, powertrain control module, an erroneous sensor input, or faulty connection. No fuel pump hum could be caused by a bad crankshaft sensor, fuel pump, pump control relay, or a faulty connection. A faulty auto shutdown relay or incorrect commands to it could also cause a stalling condition. Try also applying perhaps 20 percent throttle during a restart attempt. If this results in a successful start, the idle air control motor may be sticky or failing.
I’mhoping your repair tech can egg-on the fault by idling, then driving the truck to witness the fault personally, then pounce on it with a preplanned strategy of diagnosis. I used to drive customer’s cars home for the evening as a drivability tech. Besides improving the chances of performing diagnosis-during-fault, I gained a better understanding ofmy customer’s fear and frustration of entering tennis shoemode at an inopportune time.