I had a similar problem on one of big trucks. The truck just stopped running, like it ran out of fuel, I still had a half of tank of fuel! I would put 5 gallons of fuel in and it started right up but when it got back to a half of tank it died again. Turns out the rubber fuel line from the tank selector valve to the fuel filter was loose. The pump was sucking air and not fuel. I guess it worked "harder" pulling up fuel from a 50 gallon saddle tank that was half full. Put a new rubber line and new clamps and problem solved. So check all your fittings.

John G

1942 G5106 1.5-ton Chevy cargo dump Gallery page




Old Dominion Stovebolt Society
T/Sgt. Gott (28 years of service with the USPP)
1940 Chevy G506 4112 cargo dump
1942 Diamond T G509 969A 4 ton wrecker
1942 Ward LaFrance G116 series 2 10 ton wrecker
1944 Ward LaFrance G116 series 5 10 ton wrecker
1931 Ford AA with a WEAVER crane
1944 Sterling HC 165 tractor
1944 Autocar U7144T w/ 10 ton trailer