Cat D5B air in fuel lines

AC Tim

Member
I have air (very small bubbles almost like foam) when I crack the fuel lines. Fuel pressure is fine for 5 minutes, then it starts to drop. If I re-prime with the primer p hand pump, it starts back up, but does the same thing within minutes.

I am thinking that the fuel primer pump is faulty and allowing air in.

Does this sound reasonable, or could it be something missing?

Thanks Much
 
had that problem, in my case it turned out to be a worn shaft on the transfer pump, put on a rebuilt pump , all set
 
Have you serviced the fuel system,is the sediment bowl clean is the filter clean,you should have a decent flow at the transfer pump,usually if the transfer pump seal is bad it lets fuel into the oil so check that is not happening,see the tank is vented.
Good luck & happy xmas
AJ
 
The primer pumps on Cats do have a habit of sucking air. Not knowing what kind of filter you have you could pull the filter and check for cracks in the filter base. I have seen filters crack around the base also. I'll check back and see what you've tried. There are other things that can happen also.
 
I should have added this additional info. I was grading, and it was running perfect, when I ran out of fuel. i filled up the tank, and primed the pump with the hand pump, and noticed it was leaking out of the piston on the pump when depressed (slightly, not a lot). Engine would start and run for a few minutes and then stop. This is why I was thinking the primer pump might be bad. The weird part, is that it was running perfect just minutes to running the tank dry.

Merry Christmas
 
have had that happen with primer pump. it should bolt to filter head with 2 bolts. make a test gasket to block off holes & try.
 
Bob got it right. I had sediment blocking the fuel line from the tank. I stuck a wire through it and out came the dirty fuel. Put it back together and primed it, and it started up and ran perfect. i am going to put a new primer pump on it though, because of the leak.

Thanks much for the help
 

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