Yesterday morning noticed my 98 ram, 360 4x4, seemed to have a slight misfire while I was on my way to work. Thought I'd check it out when I got home. But when I tried to leave at lunch, it started and ran rough for about a second, then died. Now the engine turns over, and sometimes it seems like it tries to start, but it just won't. It's still sitting in the parking lot. I know there are several things that this could be, where do I start?

 

Crank position sensor?
Spark while turning over?
Fuel pressure (if you have a gauge handy)?

 

I'll get a spark tester before I go back to the truck. I don't have a fuel pressure gauge, but I'll see if I can borrow one. How do I test the Crank position sensor?

 

Also pop the hood and do a quick visual inspection. Make sure no spark plug wires melted on your exhaust. I had a similar issue with my last truck. The plastic wire holder that clips on the valve cover stud broke off and the coil wire dropped onto the exhaust manifold and melted.

Another thing: how old are your wires? Was it damp out when it didn't start? If your wires are old or cracked they will short out before the arc gets to the spark plug. You can check this by lightly spraying water on the wires while someone cranks the engine.

 

Not sure how you would "test" the CPS, but for the cost, you can just replace it. (Easier said than done I guess). They seem to be a common problem and I carry a spare with me in the truck now. Mopar brand, though.

 

Not able to get the spark tester tonight, I'll try that tomorrow along with fuel pressure. The cables are about a year, maybe 18 months old and still looking good. Still firmly attached. I did notice when I turned the key on, I didn't hear the fuel pump pressurizing. Is it my imagination, or shouldn't I hear a bit of a 'hum' when the key is first turned on?

 

I think 3 seconds worth. Try swapping relays with a known good one.

 

If you get spark, chances are good the crank sensor is fine.

Scanner to check for codes wouldn't hurt either.

 

I confirmed that I do have spark. I do not have fuel pressure with key on or while trying to start. Needle doesn't even quiver. Swapped the horn relay for the fuel pump relay, still no pressure & horn still worked. Swapped for the ASD and horn relay with same results. So is this a fuel pump issue, or is there something else that could cause this?

 

Thump on the bottom of the gas tank a couple times, then see if it will start.