I have a 1990 Dodge w350 with the 5.9L cummins. In January truck started chugging and blowing white smoke. Had to reprime the system to get it to start, still didn't run right. Replaced the mechanical lift pump and it ran for about 2 weeks, and then started all over again. Dropped and cleaned the tank,thought that was the problem. Still would not run unless I reprimed the fuel system and then only ran for a minute. Checked the lift pump and noticed that the lift pump would not pump fuel while turning the engine over. Took the lift pump off and pumped it by hand and got fuel. Cam shaft lobe shot ?

 

eather that of you got a defective pump

 

It is doing the same thing it did before I changed it, mechanic told me that he thought the lobe might be worn, thinking about going to a electric fuel pump. The pumped worked when I pumped it by hand ?

 

dont know why it would be worn, how often was the oil changed? how many miles are on the truck

 

200,000, he said that he has seen semi tractors that only had 140000 and the mechanical fuel pump had worn the lobe down and they had to replace the cam. Hate to spend another $95.00 and then have to replace it again, the last one only lasted two weeks.

 

oh wow i had 280,000 miles on my truck before i melted the piston, the lobe was still a thousanth of an inch still in spec for a runnable lobe. i was actually thinking about getting a 12v pump as well to run with my mechanical just for safety reasons, but then again i have a fuel pressure guage

 

It is driving me crazy, it has not run since the first week of Febuary. I need to find a way to check the lobe to see how much lift it has. I would prime the system and it would run with the fuel filter off until it drained the fuel in the system. With the filter off no fuel was coming out of the filter housing.

 

just my input, I did get a defective one from the parts house at first when I changed mine.

 

Check for air leaks. The factory line likes to fall apart back at the tank and let in air. Also heard of lines rusting through. If its leaking down it has an air leak. The VE pump will pull its own fuel. Wont like it a whole lot but it will do it.

 

ya your cam lobe should still be fine them lift pumps dont put alot of were on the lobe. your intake lobes should be worn more than you fuel pump lobe