So I picked up an 86 350 with a 6.9 for 500 bucks. Right away i noticed oring on return leak and lift pump leak. Replaced lines and rings and lift pump with fuel filter. The damn thing still wont stay running more than a mile. when i push the shrader on filter housing it pumps like hell for the 1st couple minutes then dies off. So i know the high pressure transfer is sucking the filter dry before lift can keep up.....

Things ive done

new orings lines and lift pump.

took cap off in-case tank vents plugged.

put tank at 3\4 full

bypassed seperator to eliminate variable, no luck....


Is there a control device to control the return back to tank.... This thing will drain a 3 gallon container at idle in about 3 minutes. It seems like thats way too much volume on the return....I realize it cools pump with fuel but seems a little excessive. Is that normal?

Today i am checking all lines. The truck sat for 3 years. Any ideas would be appreciated.....

 

Idea take a fuel can run line to where seperator was and take return line off selector switch stick it in can also. See how she runs. Mine set up for over 5yrs had to drop both tanks had mud in them. Might be a clogged pickup tube or could be cracked.I have this same problem on my front tank going today to get another sending unit.

 

like he said, but i would take line off the pump on side of block, run that into a tank and reprime system that way. see if it runs then, if does it is somehting in the lines or tanks.