Posted by scott56 [162.158.255.133] on Thursday, May 30, 2019 at 16:16:46 :
Fuel system issue. Symptom, runs out of gas, confirmed by no gas in carb float bowl.
Each time this happened, I was not sure how much fuel was in the tank but tank would only take 3-5 gallons to fill. I have since drained the tank, sat overnight with soapy water, drained and rinsed with garden hose for 30 min plus, then blew air through for the better part of 24 hours. I blew air back threw the output and it did not feel plugged at all. I did run the engine for an hour in the garage at varying rpms before that gas tank flush and it did not run out of gas. It did, however, when I drove it for about 5 miles on city streets. Tank must have had about 13 gal in it and the carb bowl was empty. Prior to this I installed a see thru filter at the tank output and found a few “course pepper” particles but not much else. Initially I found some particles in the fuel pump glass bowl and none in the gas bowl filter just before the carb. It appears the filters have stopped any particles from reaching the carb. I then added gas, 2 gallons at a time and marked on tape where the gauge read. At 10 gal, the gauge read ˝. I stopped there for now. This all confirms my observations that the carb is running out of gas while the tanks has a significant volume of gas in it.
I tested the fuel pump. It reads 5.5 psi and produces 3 oz of gas in 15 seconds. This is consistent with a good pump according to several articles I read.
Possibilities?
1) Vapor Lock. The gas line from pump to carb is about 2 feet long and loops away from the exhaust similar to other trucks I have seen. I have the pump heat shield installed and the ˝” fiber spacer under the carb to manifold. I ordered some heat wrap to help insulate the gas line from the frame to the pump and pump to carb. The exhaust manifold heat valve is frozen in the ˝ open position.
2) Hole in gas tank pick up tube. I think that could cause the symptom of having an empty tank.
3) Float valve/needle valve. Looks OK to me and the truck did run for an hour without stopping. Also the idle circuit was repaired by Treadwell Carb. I need to call him if he verified the float and valve were OK?
4) drive it with an external fuel tank and see if the problem happens.
I am ruling out distributor issues for now since that last time it quit, I opened the carb immediately and saw the float bowl empty. I did order an Accel Condenser. Do not want to add a new element in the investigation yet.
Thanks, You have helped me get this far.
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