Fuel Lift Pump 95 Dodge 12v 5 spd:

[DieselPwrRam]

My last fuel filter change I noticed fuel leaking from the base of my primer bulb on the lift pump. I did fill the fuel filter with diesel for less priming. Glad I did the primer button on the old pump just leaked and wouldn't prime. After the normal sputter and rough start I got the engine to run. It smoothed out and ran fine on my road test.
The biggest issue I was having was starting my engine when I got to less than half a tank of fuel. I suspected losing my prime due to sucking air the lift pump primer bulb. I read several posts regarding the O ring as a source for problems. I couldn't find anything as to the size needed. This is my only vehicle I wasn't going to chance the O ring replacement and have other issues. I went to Freightliner and just got a new lift pump. I have almost 160,000 miles on the old pump and decided to replace it.
I tackled the repair from the top. Removing the fuel filter made it easier to get access at the lift pump. I installed the new pump using new studs and nuts and torqued it down. Having little leverage installing the pump from the top this method was the only way to go. The hardest part of the job was connecting the fuel lines. Others have tackle the job from the bottom and side with success. There are some posts regarding this method.
The main reason for this write up was regarding the O rings on the old lift pump. I took these photos for the benefit of those who only wish to go with only the O ring repair. As you can see there are two rubber O ring on the primer shaft. My old O ring were not split but more flattened out on the outer edge allowing fuel to pass. I found a chart for some sort of sizing (refer to photo). The large O ring (R-54) has an I.D. 7/8 , O.D. 1- 1/16 , THK 3/32”, the next closest size was (R-53) I.D. 13/16”, O.D. 1- 1/16”, THK 7/8”. The small O ring (R-48) I.D. 9/16 “, O.D. ¾ “, THK 3/32”. These are based on standard rubber O rings used in faucets repair. I sure there are other sizes maybe better or worse but at least this is a starting point or range to keep in mind.
My truck runs great and seems quieter. Hope this provides some useful info for those contemplating taking on the fuel lift pump.