1977 Chrysler 135 model 135HG fuel pump parts question

[seattle scott]

Wasn't getting any fuel past the pumps so I am in the process of rebuilding them. When I removed the lower fuel pump (pump cover part FA439746) it had a brass tube extending out the back into the crank case area. The top pump didn't have this tube and the tube is not shown on the fuel pump parts diagram. Anyway, the tube must have fallen out of the pump cover between the driveway and the work bench and is lost.

So is the engine going to run fine ( at all ) without the brass tube?

 

[Frank Acampora]

Re: 1977 Chrysler 135 model 135HG fuel pump parts question

I am reasonably sure that you are describing the oil recirculation tube. It is on a 90 degree elbow on the top of the bypass cover. There are only two of them-- Usually one on the top and one on the third cover down. The engine will run but you must plug the hole otherwise you will lose crankcase compression. Now, my question is: Did the small brass tube break off the elbow and fall out or are you missing the elbow? The tube is designed to squirt unburned fuel and oil directly into the cylinder.

The purpose of these tubes and the recirculating system is to collect unburned fuel and oil which puddles in the bypass and burn it before it becomes a large slug and enters the cylinders. This system mainly functions at idle and its there to improve idle.

 

[seattle scott]

Re: 1977 Chrysler 135 model 135HG fuel pump parts question

Thanks Frank, but I think you are describing something else. The tube went into the back of the lower fuel pump into the hole that leads to the pump diaphram and is part the system that uses crank case pressure to move the diapham which is the "pumping" force of the fuel pump. Snce the missing tube is on the "dry" side of the fuel pump diaphram, it doesn't pass fuel or oil only air pressure/vacume from the crank case.

 

[Frank Acampora]

Re: 1977 Chrysler 135 model 135HG fuel pump parts question

I have never seen a bypass-cover mounted fuel pump with a brass tube in the pressure port. As long as the port is open from the bypass to the diaphragm the pump will work. All of these pumps I have seen simply have a hole in the back of the cover communicating with the large diameter part of the diaphragm. The smaller part is serviced by an external hole with a 90 degree elbow and a short length of hose from the nipple on the crankcase. In the case of twin pumps, the top pump is on bypass cover #2 and the hose for the second stage comes from a nipple on bypass cover #1 (top cylinder). The lower pump is on bypass cover #3 and the second stage hose comes from a boss on the crankcase at #4 cylinder. Output of bottom pump is fed into the black plastic screened input of the top pump.

 

[seattle scott]

Re: 1977 Chrysler 135 model 135HG fuel pump parts question

Perfect. Thanks Frank.