Bad injectors?

[Ray Sharpe]

Hey guys. My '99 recently started to make a popping noise when idling hot. You can't here the noise when you open the hood, but it's driving me batty :mad: when i'm driving around town because it is so loud inside the cab. I thought it might be the vacuum pump, but it wasn't. Would this be caused by a leaky injector? Thanks for the info. PS. the truck now has 150 000 miles on it with orig. pump and i***.

[DmaxMaverick]

Check you injector LINES. If they are touching anything solid, or if the isolators are loose, the injector pulses can resonate through the chassis or cab. They can be very loud. Other than that, you could have some other engine/accessory/exhaust part contacting something else.

Good luck.

[Ray Sharpe]

I don't think that the lines touching each other or something else could make as loud a noise as what this is. Also, the truck doesn't make the noise when you first start it in the morning, so I don't think that this is the problem. I think that there is one injector that is leaking into the cylinder causing it to pre-ignite thus, the popping noise. But thank-you for the suggestions. Keep them coming, thank you.

[Turbo Al]

A sticking valve will make a rather loud pop that sounds like it is coming form the air cleaner area. Also it will come and go.

Al