Truck will start up and all of the sudden die then i have to have someone push in the valve above my fuel filter and let me crank my engine untill fuel comes out of the valve then it will start right up. It only gets air in the lines when its not parked on level ground and sits for at least 4 hours. It gets alot of air in it when it happens because it sometimes takes a minute or two of cranking the engine to get all of the air out almost like all the fuel returns to the tank. I think i have a bad lift pump but lately its been starting right up but it does idle rough like its getting air in it but if i let it idle for about 1 minute its fine which makes me think it was an air leak in one of my lines. I bought a new lift pump but i dont want to put it on untill im sure theres no leaks in my lines, no reason to ruin another lift pump. Is there anyway I could find an air leak in my lines? Any ideas on what it might be please put your 2 cents in, im new to diesels and im 16 and have limited resources and money, thanks for any help!

 

Do you still have the factory water separator on the firewall? If so, bypass this thing. I don't have a early diesel, my 89 did not come with this separator. But all the owners with the older trucks bypass this thing, because it lets air in the system.

If someone has already bypassed the separator, then the next common source for air leaks are the o-rings around the injectors. I had to do this to mine also. When the o-rings get old, they get hard and can let air into the return system that goes from injector to injector. You can get kits to replace these o-rings, or just do what I did and re-use the plastic caps, and go to tractory supply or someone else and get #111 o-rings and some 3/16 fuel line to replace the lines between the injectors.

Have you ever stuck a straw down in a drink, put your thumb over the end and then drawn the straw and the liquid out of the glass? That's the same way these diesel fuel systems work. If they are totally sealed, then the fuel stays trapped in the system. Any little leak anywhere, and it will let the fuel drain back to the tank via the return line to the tank.

 

I am running an electric fuel pump to my fuel water separator and it works great. I also have a primer bulb the ones that are for boats on the drivers side it helps to prime the system. As far as the air I would check or just replace the fuel lines. Hope this helped

 

My grandpa ran into a old farmer he knew at the parts store ended up we just needed to bleed it better. Finnally got the air out took 20 mins of bleeding