Loosing prime detroit 60

It is an air leak in the system. You should pressurize the system to find where it is.

 

You could put a check valve between the fuel separator and fuel line. The air leak could be behind the check valve. It doesn't matter that the lines are new air is getting into the system that's why you are losing the prime. You have to locate from where..

 

You’ve got a bad check valve. It’s located on the back of the head, on the return (top) line. Rarely they’re located further down from the head. Yours should be right at the head. Replace it, problem solved.

 

Lots of info about these in the search block.

 

Check valve behind the head, like mentioned.

 

Check valve holds fuel in the head. When it’s bad, it drains into the return. I think there’s also a check valve built into the fuel pump also. Easiest way to pressurize the tank is by blowing air into it, using a rag wrapped around the blow gun. Will prime the system quick. Once when I didn’t have any air in the Trucks tanks, I used a mini air compressor, cut the end off the hose, hooked to one of the tanks vent line, secured with hose clamp, with both caps on, and other tanks vent line crimped. It worked great. Took a long time to build pressure, because my tanks were low. Be careful, don’t need much pressure. Less than 7 lbs. I believe. I put 18 lbs in mine. Big mistake. Don’t try to remove caps till all the pressures bled off. If you do, it will blow off once opened and break your hand.

 

You can take the check valve behind the head apart and see if you have a broken o'ring. There is also another check valve on the fuel water separator inlet hose, take it off and see if it has any debris suck in the valve.