Engine/Transmission (1994 - 1998) Lift Pump Issues

[drrhoades]

My question is; when you bump the starter you should be able to hear the lift pump run? If so how loud is it and what does it sound like. I am imagining a fuel pump on a gasser sound. Is there any other way to test it other then bumping the starter. Also how much is a new lift pump and how hard are they to change. The reason I am asking this is that when I changed my fuel filter the other day I cracked the banjo fitting to let air out then I went and bumped the starter to try and fill it with fuel while letting the air out so it would start easier. Well I dont think it filled the canister at all. I just manually pumped it until it was full then she started right up after the air got out of the lines. So the manual prime works for sure. Also the engine has been running a little different ever since I changed the fuel filter and got air in the lines. It almost seems like it is missing. Also that was the first time that air has been in the lines the only other time I changed the fuel filter I primed it all of the way by hand and didnt even try using the lift pump to fill the canister.



Also would a lift pump not running cause a decrease in fuel mileage? Any help or suggestions would be appreciated.



Thanks,

Doug

 

[Dbonzi]

The lift pump on your 97 is mechanical. The only way it pumps is with the engine running. This is why it didn't fill your canister.

Dennis

 

[fishjack1]

Having just changed mine last Thursday I can tell you a couple of things - Price $165. 00 including tax.

Cummins Part number: 3936316



To my knowledge I had no symptoms indicating it was about to fail or was going out. I replaced mine because I had a fuel leak that only occurred with the engine running. Fuel was leaking form the weep hole on the left side of the lift pump. This (from what I was told) was an indication that the pump was about to go out.



I changed mine from under the truck - remove the starter and you'll have pretty good access to the pump. (if you have not already now is a good time to check the contacts on the starter and replace if necessary with some of the super contacts) My truck is a 4x4 so that made it a little easier. The job (after I found the pump at a local Cummins parts store) only took about an hour and a half. The two hardest things to do are get the fuel line fitting loose on the top of the pump from the fuel filter. The other is reinstalling the pump while having to push in on the resistance of the push rod spring while tightening the 2 bolts that hold it in place. The new pump is larger and will require modification of the fuel feed hose from the fuel heater unit. I did not remove the fuel heater assembly when I changed mine and only replace the gasket between the fuel heater and the new lift pump.



Truck does seem to run better and starts faster now.



Good Luck.

 

[drrhoades]

Ok I guess I should pay more attention to what I am reading, I knew that it was mechanical I guess I just had a brain fart. My truck starts on the first rotation everytime I can barely bump the start without it starting. So I guess that it is fine. Well here is another good example of paying for a membership to this website. Thanks for all the help.



Doug