Sunday, February 21, 2016

Fabricating & Installing Fuel Pump Drain Line

The task for the afternoon was to fabricate and install the fuel pump drain tube. The fuel pump’s drain tube is fabricated from two pieces of rubber fuel line and an aluminum tube which needs to receive three bends. Right off the bat a mistake was almost made in cutting the rubber fuel line … the instructions say to cut both FF-01224 and FF-01225 fuel lines per figure 1 dimensions. Figure 1 shows two fuel lines with a measurement of 2" above them. It is a good thing I looked further forward in the plans to realize the second fuel line needs to be much longer than 2" … in fact it needs to be 19".
At first glance it appears figure 1 in the upper left is showing both fuel lines are to be cut to 2" … NOT SO, the drawing is misleading, only FF-01224 is 2" … FF-01225 is cut to 19" as can be seen between my fingers.

FF-01223 is fabricated from 1/4" aluminum tubing cut to 17 3/8". Both ends of the tube are flared then the flairs are ground down to leave approximately 1/32" of a flange. Basically, the idea is making a ridge for the hose clamps … but not so high that the tube won’t fit into the hose.
The flair on the left is a normal flair … the flair on the right is after grinding most of the flair off creating a ridge for a hose clamp.
FF-10223 after grinding down the flairs ready to be shaped per the 1:1 drawing.

To make the tube as precise as possible to the drawing, I ignored Van’s radius angle given for the middle bend and used a protractor to determine that angles the bends were … from right to left they are 50 degrees, 40 degrees and 30 degrees. I started with the biggest bend on the right and worked to the left. Since the drawing is a 1:1 to scale drawing, a straight edge was used to determine where the bend begins and the tubing was marked at that spot and placed in the tubing bender at the 0 degree mark and the first bend was made to 50 degrees. The point where the 40 degree bend begins was determined and the tubing was marked at that spot and placed in the bender at the 0 degree mark and bent to 40 degrees,  checked with the protractor, then placed on the 1:1 drawing for verification.
About to make the second 40 degree bend with the tubing bender.
The first two bends are completed and the tube is adhering to the drawing very nicely.

Before making the final bend, I wanted to check the fit on the engine to see how all this is working out. Four Adel clamps are used as hangers for the tubing … two larger Adel clamps go around the forward and aft oil return tubes and are used as hangers  for the smaller Adel clamps that will secure the FF-01223 tube. To aid in being able to get the mounting screw inserted, a piece of safety wire is used to compress the Adel clamp.
A piece of safety wire holds the Adel clamp compressed … this makes it easier to install the screw and nut.

With the clamps in position, the tubing was placed in position and it looked good. I made a mark on the tubing where the aft Adel clamp would be securing it just to make sure the final 30 degree bend began aft of the Adel clamp. The tubing was removed and the last bend was made.
Completed bending of the FF-01223 tubing. It is now ready for instillation.

Prior to installing the FF-01223 tube, the 19" piece of hose was attached and secured with a hose clamp and the two smaller Adel clamps were placed onto the tube … safety wire was used to compress the Adel clamps so installing the screws would be much easier.
The FF-01223 fuel drain tube assembly ready for final installation.

Instillation of the FF-01223 tube went smooth … it was connected to the 2" hose on the fuel pump and both Adel clamp hangers were secured with a screw and nut. The 19" hose is routed between the two coolant lines aft to be wire tied onto the fuel line from the Gascolator.
Transition of the FF-01223 fuel drain line from the fuel pump to under the engine.
The FF-01223 fuel drain line traversing the underside of the engine.
The aft transition from the FF-01223 aluminum line to the 19" FF-01225 fuel drain line hose.
The  19" FF-01225 fuel drain line hose wire tied onto the fuel line coming from the Gascolator.