I've been chasing this tapping-knocking noise for 2 months and can't seem to get a handle on it.Had Marty re-man the injectors,ran the valve's,new fuel filter,new prefilter,had a fuel pressure guage on it with about 24lbs at idle but the guage pounded itself to death before i could get a higher rpm reading.Replaced the overflow valve,no change The noise is best heard on the drivers side, high up.Sounds harmonic to me.Will low fuel volume cause this?Is there any one in the Clermont Fl area with a 12 valve?Would like to listen to your's and compare notes.The noise is louder at times and the truck runs good at times, and some loss of power at times, almost no noise at startup when cold.I need some help here fella's

 

My '98 does not have this noise. Many others have reported it. Just as you have, they replaced parts and still have it, or it returns, but sometimes it's fixed. No sense to it. A search will turn up much discussion.

 

mine has the same noise i've posted about it before. Seems like alot of guys have it but can't find it. I'm still looking for mine to. Like yours mine sounds high in engine i'm thinking maybe pushrods or something of that nature.

 

Yes,it does sound like valve clatter.I'm going to run the valves again this weekend and see if that helps at all.