3406b air build up in fuel system

We pulled the motor from another truck and it ran fine now its in another truck it will run for a few minutes untill it sucks the fuel out of filter runs ruff and dies. We have noticed that there is a lot of pressure when we took the filter off and we are getting no air anywhere either. What's wrong?

 

The first thing you need to do is be sure the return line is clear, that is why you have preasure in the system.
Then you need to find, where the air is sucking in, if the primary filter is filled then the engine ran and the level goes down, the air leak is before the filter. If you are using a 1212 check the drain is not open a bit.
Just a thought!

 

I dont know if it matters but the motor is a 3406b. I usally dont have to mess with this stuff but what is a 1212? And the motor came out of an 86 and now is in a 96. We changed everything over from the old motor except the exhaust mainfold and we put a cross over for the fuel tanks thats it. I didnt put the motor back in someone else did but theres a line coming off the main filter going down to a valve which there is a line coming off air pump that goes down to the same valve, does ths sound right?

 

the 1212 is a fuel filter,cummins use but is good for cat too is depend what base you use !!!

 

I am no expert but I don't remember any lines from my air compressor hooking into my fuel system any where on my old B model cat.

Can you post pictures ?

 

Mine either. Something isn't right!

Might be bad fuel lines?

 

Ill try and post pics tommorrow. But if you are looking at main filter to lines come off it one goes toward the back of the truck the other towards bottom/front of truck and there's a line that comes off air pump and goes to the same area as the fuel line. On the pump I have 2 lines that go back to tanks it looks like one coming off the side going to intake? 1 coming off bottom going to front cover and the big one going to the area of the fuel line. The filter is a off 2749.

 

The black line from the pump is going down to this block which is at the bottom towards the front of motor and the small line is going to fuel filter. Ill post pics of the filter to.

 

That is your transfer pump and no air lines run into it. If you look closer your probably confusing lines or the air line is running past it.