I noticed my lift pump is leaking around the primer boot and was wondering if this can be repaired? The boot isnt torn and the pump itself is only about 4 years old. Am I correct to assume that this leak is letting air in the system? 

If fuel is getting out, that means air is getting in.

Is it possible to repair the leaking primer pump? 

Just replace the lift pump. It's most likely wore out.

Some of the older designs had a O-ring you could replace, but I don't think yours will.  

If yours looks like this, replacement is your best option.

 

If you don't mind it being yellow.

http://www.ebay.com/itm/NEW-TAKE-OFF-FUEL-LIFT-PUMP-4BT-390-CUMMINS-PART-3936316-/301747944699?hash=item4641943cfb:g:ZwkAAOxydlFS5M5-

And yes, it has the possibility of leaking air in as well.

Edited January 23, 20169 yr by Cowboy

On 1/21/2016 at 9:23 AM, Mopar1973Man said:

Just replace the lift pump. It's most likely wore out.

It was replaced 3 years ago. I was I another town visiting a friend when the old one took a dump, Autozone was the only place that had one in stock. Obviously it wasn't a quality unit. 

13 hours ago, Cowboy said:

Some of the older designs had a O-ring you could replace, but I don't think yours will.  

If yours looks like this, replacement is your best option.

 

If you don't mind it being yellow.

http://www.ebay.com/itm/NEW-TAKE-OFF-FUEL-LIFT-PUMP-4BT-390-CUMMINS-PART-3936316-/301747944699?hash=item4641943cfb:g:ZwkAAOxydlFS5M5-

And yes, it has the possibility of leaking air in as well.

Mine looks like the one you posted. For $62.80 shipped it could be hot pink with zebra stripes for all I care lol.