The_Head

How would one know if they installed a HP piston lift pump by accident? How bad would the IP leak?

Just curious because my IP leaks pretty bad now. I got like 8.5 mpg city last time I topped it off.

BC847

The 2nd gen LP piston (left) is bigger in diameter than the low pressure LP we commonly use (right). The springs are different as well.





Outwardly, they look the same. The low pressure LP will have a bronze bushing in the piston bore to accommodate the smaller piston (left).

wannadiesel

Too high inlet pressure will blow out the front seal and put lots of oil into the crankcase. You won't get an external fuel leak on the VE.

Benjamin b2

did it, dont do it

The_Head

Thanks guys. I was worried I had the wrong lift pump installed. I'm having a brand new IP installed next week and I don't want to mess it up.

jesussaves

Is part numbers and instructions still correct in the sticky threads

wannadiesel

Yes. Even if a part number has been superseded your Cummins dealer can figure out what you want.

Benjamin b2

so you think

Firstgenfanatic

I was given a brand new piston lift pump from a friend. He has no reciept and no idea was application it was for. Basically it was part of a master rebuild kit for a marine 12 valve. I have not opened up the pump to see if it is a high or low pressure. The pics BC847 will help me determine that. My question is: Can a person interchange the internal parts from HP to LP, or vis versa? I really would like to know this, otherwise I might have a HP pump this is useless to me.

oliver92

even if it is a high press pump its not usless you can install a press regulator in between the lift pump and inj pump to bring it down where you need it

JustRamIt91

Unless you run a pressure regulator and return line like they do on fuel injection. wouldn't that create excessive wear or possible damage to the LP?
Also if you were to run a pressure regulator with return line, would that help to level out the fuel pressure to the pump and make more power because there is no pressure drop?

wannadiesel

A dead end regulator won't hurt it, you don't really need a bypass unit with a piston pump.

Regulate AFTER the filter.

JustRamIt91

Thanks.

If you were to use the highpressure LP with regulator, would you increase your top end power?

wannadiesel

Only if you were losing case pressure in the VE due to poor fuel supply.

Firstgenfanatic

I personally want to convert my HP lift pump to a LP..........can I do this?

I am assuming you can buy a new spring, piston, and bronze bushing? I realize you can regulate, but I prefer it to be a LP pump from the get-go.