I have an annoying sound coming from my engine. At first I thought it was a valve or a rocker arm making noise. I used a mechanics stethoscope and all sounds normal within the valve covers. The clicking sound seems to be coming from the fuel rail, but no specific injector. The noise increases slightly with rpms but not as if it was a mechanical engine problem.

Any ideas ???

 

The injectors are basically just solenoid valves, and some tend to be louder than others. Check your injectors, and see if one isn't just loud... or, maybe you are hearing all of them. (this was a common event on the old TPI GM motors.)

Also, might be an exhaust leak.

 

I have an injector that occasionally "ticks". Try running some Marvel Mystery every other tank for a while to lubricate them. Annoying, but it goes away. It adds "character" to the vehicle.

 

I use one ounce of TC-W3 two cycle oil per 5 gallons of gas in every thing with a four cycle engine in it. Seems to be a little smoother and improves mileage slightly.
Made a big difference in consumption on the John Deere lawn tractor.