Engine/Transmission (1994 - 1998) P7100 pump noise

[gklotz]

95 Dodge, 300 K miles

Runs great ... recently I hear a melodic tappet type noise while driving at all speeds.

It varies with throttle position and can disappear at cruising or come on louder depending on acceleration position,

 

[Missouri Mule]

Try running lubricant/cleaner in the tank. Mine did that years ago. Any decent one will do (amsoil, power servce...).

 

[gklotz]

Thanks for the suggestion . Just put in "PS" injector cleaner with slick diesel lubricator. Will see if I notice an improvement. Thanks

 

[GAmes]

My guess is the noise is coming from the lift pump. Over time the internal spring gets a little weak and the pushrod loses contact with the cam for a millisecond on every revolution, causing a tapping noise. How many miles has it been installed?

 

[gklotz]

95 300,000 miles on original P7100. Weak springs on the pump tappet assembly sounds like what I'm hearing.

Guessing I can drive without fear of sudden failure

Are these springs ever part of a minor pump rebuild?

 

[GAmes]

The p7100 is the injection pump. The lift pump is the supply pump. http://www.genosgarage.com/REPLACEM...98/productinfo/PUMP_4988747_KIT/#.VV9hcEJ_ljo No rebuild kits that I'm aware of. Be sure to change the fuel hose as well. http://www.genosgarage.com/MOPAR-FUEL-ELBOW-HOSE-94-98-59L/productinfo/MOP-04746638/#.VV9htEJ_ljo Normally a tapping pump will not fail suddenly, however, the tapping can't be good for the cam lobe.

 

[gklotz]

Thanks for jogging my brain.
Did not consider lift pump - will order pump, elbow hose and upper gasket.
For the price it's worth finding out.
Will let you know in a week or two.

 

[gklotz]

your right' noise gone. could tell difference when bench pressing new verses old. thanks for your time. GK

 

[2Farr]

I have the same tapping noise, just started this week at 198K. I have a new lift pump in stock so I guess I know what I'll be doing today.

 

[MLee]

These pumps have been changed in the past and are quite for a while and then the tapping comes back. Its what they do. I wouldn't worry about it. After having done it once.
Get the studs and put them in first they help a lot with installation.