Well, I have done a search on the ticking of a 12 valve and most everything points to a bad lift pump. Here is my delimma. I had the truck in the injection pump shop to be checked out for no power at 50 mph about 8 months ago. That resulted in the prefilter being replaced, along with the overflow valve. The tech said that my fuel pressure was at 5 at idle and dropped to nothing when driving, the prefilter screen was clogged after switching over to biodiesel.
After the O/F valve and the screen was replaced, my fuel pressure runs about 28 at idle and 20-24 at WOT. I think that is pretty high, or at least to indicate that my lift pump is ok. However, since I got the truck back, I have had a ticking when vehicle is first started that will usually go away once the truck has reached good operating temperature. This ticking is noticeable on the left side, at idle, in park and driving down the road sounds like it is coming from the drivers side floorboard. I noticed it especially bad this morning when I was about 50 feet from the truck, the ticking sounded louder than the engine. I drove to work, noticed it almost all the way(16 miles) and then when I got to work, popped the hood and could not locate the tick. It was pretty much gone and all the other clattering sounds drowned it out. Where should I start?
Chris

 

As u stated..

it all points to a bad LP.. or a failing one at least.. Hard to tell, mine was ticking when it went out, and after replacing it, well there was no more ticking at all. Some people use a stethoscope (spellcheck?) to try and isolate the sound, But if your truck has high miles it wouldnt hurt to replace it, and just MHO, it wont hurt to put a FP gauge in that truck.. it sure helps to monitor all these situations...

Rick

 

Mine does the same thing. When my truck was in the shop having other work done, the mechanic that owns the shop told me that was common and it's fuel running through the metal lines. I assume he meant it's the return line possibly tapping against the frame. Anyway, I quit worrying about it and so far no problems.
As far as the prefilter, I had the same thing happen years ago before biofuel was available. Since then I usually check it with every other fuel filter change. On one occasion I had a few little plugs in the screen before I ran some B20 biofuel. I cleaned it best I could and reused it. After I had run a few tanks of the biofuel I changed the main fuel filter. Some months later (after I switched back to straight Diesel) I went to replace the prefilter screen (8 bucks from Cummins) and the screen was spotless! From what I understand the biofuel can actually clean your system and that's why important to change the filter after the first few tanks.
One thing to be careful of when reinstalling the prefilter screen is to make sure you get a good seal and the housing is secure when you reattach everything. I had mine back off a little and it was sucking air causing me all kinds of starting problems.

 

I just went out to try to find the ticking and it is still quite now. What makes it come and go? It seems like if it was a bad lift pump, it would tick all the time.
Chris

 

Ok I did isolate the noise by pushing on the primer button when the truck was ticking. It quit, so it is the lift pump. Now, will this ticking mess up the cam? I don't seem to have a pressure problem, just noticeable ticking
Chris

 

There is a plunger in that pump that rides on the cam. When the spring wears out, the plunger is allowed to "float" away from the cam lobe causing the infamous "tick,tick,tick...".


The return line can make some noise as the excess fuel chatters past the overflow vavle.

I would not be worried about the lift pump plunger damaging the cam as much as having hard starts and low fuel pressure/power.

 

I went and bought a pump today, along with the studs. Had to go all over town to get them. The pump was 81.51 or something like that. Will post back to let you know how it went. The parts guy said that it was unusual that the pump would go bad with only 90,000 miles on it and asked if I have been running fuel treatment. I do sometimes, but for the last year and a half, I have been running Chevron B20. He thought that might be some of the problem. Any ideas or thoughts about this?
Chris

 

Got it done. No more ticking. Took about an hour and a half of actually working on it. Tried the studs, but wound up putting the original bolts back in due to the nuts used were wrong. Worked great. Thanks for the help.
Chris