Engine/Transmission (1994 - 1998) Loud Knocking @ Idling

[SSM]

I am the original owner of my 1995 12V with over 224 thousand miles. The other day I installed a Tork Tek adjustable overflow valve (OF020). I drove the truck for a couple of days with no problems, then parked the truck for two days. When I left for work Thursday morning the engine started making a different knocking sound at idle. When I backed the truck out of the garage and accelerated the engine the knock went away, and the engine sounded and ran normal. The knock got worse when I arrived at work. Worried how I was going to get my rig home, I called a mechanic and explained my situation. His thoughts from what I told him was the new over flow valve might be putting to much pressure on my fuel pump. So I backed the adjustment screw out two turns to reduce the pressure. Nothing changed so with his advice I drove it home. When I got home I reinstalled the original overflow valve, started the truck with no change. I noticed some oil dripping from underneath the rear of the fuel pump landing on the top of the front differential. Can anyone steer me in the right direction on what to look for or replace?



Puzzled in Missouri.

Steve

 

[hsmith]

Our lift pumps are prone to making a loud ticking noise when they get a bit old. Unfortunately, the new replacement ones are made in China.

 

[SSM]

I'm sorry, the fuel pump where the oil was coming from was from under the rear of the Injection pump, not the fuel transfer pump. The noise is a very loud knocking sound.

 

[MLee]

Can you determine where the noise is coming from, by a listening rod, or stethoscope?

Fuel leakage from the injector pump? or return line? behind the OV.

As much detail as possible please.

 

[champspa]

the lift pump will knock loud when the pressure is low also . check the fuel return. put a new valve in if the pressure is low . haven't got one,stretch the spring until you get one.

 

[SSM]

I cannot figure out ware the noise is coming from, but it is VERY LOUD, enough you should wear ear plugs, so I dare not use a listening device. But I do know that the noise goes away when you increase the RPM's from the idle. The leaking of oil came from behind the injection pump near the fuel shutdown solenoid AREA.

 

[SSM]

I installed the new Tork Tek OFV020 valve, a mechanic told me that the noise might be coming from my lift pump. So I tried reducing spring pressure on the new valve, this did not eliminate the loud noise at idle. When I got home I reinstalled the original Valve and this did not eliminate the noise. I spoke to Rob at Tork Tek and he mention my lift pump might be need to be replaced. I'm thankful for all your suggestion