Post by oilleaker1 on Jul 18, 2021 17:39:12 GMT -5
Many of our Jeeps in hot weather, or at high altitude succumb to vapor lock. Recently a CJ3A with a Scout Pilot (no offense) pump, fuel filter, and rebuilt WO carburator had it. We were in a group of like machines, and it was the only Jeep to stop with the problem. It had a glass bowl on the pump so you could watch what was happening. We saw many bubbles entering the pump and assumed it was the loose inlet brass fitting. We fixed that. The bubbles quit. It still stalled not far down the trail. It had a new 1/4 inch fuel line and a rubber line section where it dog legs through the tub body gusset area. When it stalled, (engine now not running) you could see the gas boiling in the lower part of the bowl, and the level was not up to the brass outlet screen. When cold water was poured on the metal pump body, the fuel level rose up to the outlet screen like magic. Upon cranking you then could see the pump working and sending fuel to the float bowl glass pre-filter bowl. The engine then re-started. This made me think the check valves had no fuel at their location to pump. Cold water brought it into them?
?? Why and how would someone fix this???
To add: the gas tank cap removed made no difference. With cold water on the pump body fuel was delivered from the tank. The engine in the Jeep had a aluminum radiator and Willys shroud on it. It maintained 180 degrees and the engine did not seem hotter than usual.
Another Jeeper has this problem on and off and was also along on the trip, His Jeep has a assist electric pump that can be added in during vapor lock prone times. He did not use it during the other Jeeps problems. The electric pump runs forward through 5/16 fuel line. stock Jeeps have 1/4 fuel line.
So, weak or leaking check valves in the fuel pump? (I've had that on my military '51 M38)
The pump showed no bubbles so the hose isn't leaking or the new 1/4 inch fuel line back to the tank.
Water draws the fuel up so I would not think the tank outlet is obstructed.
Is there a test to see if the check valves are leaking? Put a gage on it to read fuel pressure?
Let's hear your thoughts!!!!
?? Why and how would someone fix this??? To add: the gas tank cap removed made no difference. With cold water on the pump body fuel was delivered from the tank. The engine in the Jeep had a aluminum radiator and Willys shroud on it. It maintained 180 degrees and the engine did not seem hotter than usual.
Another Jeeper has this problem on and off and was also along on the trip, His Jeep has a assist electric pump that can be added in during vapor lock prone times. He did not use it during the other Jeeps problems. The electric pump runs forward through 5/16 fuel line. stock Jeeps have 1/4 fuel line.
So, weak or leaking check valves in the fuel pump? (I've had that on my military '51 M38)
The pump showed no bubbles so the hose isn't leaking or the new 1/4 inch fuel line back to the tank.
Water draws the fuel up so I would not think the tank outlet is obstructed.
Is there a test to see if the check valves are leaking? Put a gage on it to read fuel pressure?
Let's hear your thoughts!!!!
