My 1990 ramcharger is having trouble starting and when it does it will not stay running. it just shuts off. then it will not start. I wait and the time will vary then it starts and will run for a short time and then shut right down. I thought it might be a vapor lock but it still does it after I remove the gas cap. I am getting fuel to the throttle body. I have had the fuel pump/filter/fuel lines replaced....anyone have any ideas what this might be.

 

I'm not sure how one could get vapor lock this time of the year, but here are some ideas/questions:

1. Have you confirmed there is spark after the truck stops running? You could have a bad coil, bad magnetic pickup in the distributor, bad electronic ignition controller, or maybe even a loose connection in the ignition system. Does it just die like turning the key to off, or does the engine power seem to decrease before stopping altogether?

2. Remember that the fuel injection operates off an engine management computer, even this year. If the engine isn't running, then how do you know fuel is being sprayed into the throttle body by the injector? Conversely, if somehow you see fuel being sprayed in while the engine is being cranked, but no start, then go back to question/idea 1.

One must look at troubleshooting these things in a methodical, end-to-end manner. Start with the basics; Do I have fuel? After it dies, do I have spark? Can you hold a spark plug wire near the engine block and see a spark when cranking? If not, then move to the next parts; Using a voltmeter, do I see 12VDC at the coil input terminals when I turn on the key or crank the engine? If not then you need to trace back and see if the magnetic trigger is sending the voltage to the distributor by using the ohm tester on your meter. As the engine cranks, you should see the magnetic trigger close and open.

To summarize; I don't recommend guessing and throwing parts at something like this. Doing so will cost you in the wallet and in needless frustration. Set aside some alone time, buy yourself a Chilton's or other manual, a cheap volt ohm meter and use the troubleshooting guide in the Chilton's. Once you find the problem, you'll be surprised how much you will know about your truck.

 

Thanks for your reply, I have limited knowlege of fuel injection and computers in a vehicle I have checked for spark and do not have spark at the plugs. I spoke to a mechanic friend and he suggested the crack sensor. I am going to try that. what do you think?

 

That's outstanding! I know you probably meant "crank" sensor, either that or your mechanic is on crack!

I'm no expert on the 1990 318, but I'm not sure it has a crankshaft sensor that controls the ignition system. I thought the crankshaft sensor on that vehicle only controls the fuel injection. If no spark, I'd still bet on something like the pickup in the distributor or the CDI module.

Let us know what you find.

 

Thanks for your advice Kellyfromva it was the pickup after all.running great now..............