CAT Fuel Priming Pump Installation Tips


 Common Problems / Posted 8 months ago / 152 views

CAT Fuel Priming Pump Installation Tips

 The following is based on my experience installing the CAT 206-5756 Fuel Priming Pump in my 2007 Beaver Contessa with a 400 HP C9 CAT engine.

Mounting Location:

The first step is to determine a suitable mounting location. Since you are replacing the existing primary fuel filter, you’ll want to locate the new unit in relatively close proximity to the OEM unit due to fuel line length limitations. I decided to mount the unit in the same area as the original. This required that I remove the ¼” steel tab that the original unit mounted to. A reciprocating saw with a metal blade took care of this task. I then selected a mounting location and mounted a 1/8” steel plate to the coach steel framework. When doing this, use the Cat supplied mounting template to ensure that the pump mounting holes are not positioned so as to require drilling into the framework. I mounted the plate by using 4 ¼-20 bolts after drilling and tapping holes in framework. Temporarily install 2 of the bolts to hold the plate in place and then use the template to mark the location of the pump mounting holes. Be sure you can access the rear side of the plate to install the nuts on the pump mounting bolts. Drill the pump mounting holes in the plate. If you want to apply a coat of paint to the plate to retard rusting, remove the plate and do it now.  Once dry, install the plate. Use Loctite and/or lock washers to ensure the plate won’t loosen due to engine vibration.

Electrical Prep:

Notes: All wire used is 16 AWG. You can choose to go with heavier AWG at fuse holders if desired but it is not required. The switch (9G-0011) provided in the Pump Kit is not used in this application.

The SMAKN converter is required as the pump runs on 24VDC. Note that the converter is shipped in an anti-static bag, indicating it may be sensitive to static discharge. Try to work on it on a conductive surface. Avoid plastic or Formica type surfaces if possible as static charges can accumulate on them. Refer to the bottom of the converter for wire identification. The Red/Black combination is the 12V / Gnd input to the converter. It is highly suggested that you install a fuse (10A) on the 12V source to the converter.

  1. Use a blue butt connector to attach the fuse holder to the Red wire from the SMAKN and install a 10 amp fuse.
  2. Using a blue butt connector, attach the other fuse holder to the Yellow 24V output lead of the SMAKN and install a 5A fuse to protect the pump. (The fuse holder supplied in the CAT pump kit requires assembly and soldering. I recommend using a fuse holder from an automotive parts store instead).
  3. Crimp a blue butt connector to the wire coming from the 5 amp fuse holder.
  4. Crimp a blue butt connector on the 24V Gnd wire coming from the SMAKN.
  5. Select the mounting location. On the 07 Contessa, the rear electrical bay is optimal. There is ample room to the left of the Big Boy Battery Isolator Relay.

There are 2 possible electrical hook up methods; use of a relay to switch power to the SMAKN or providing ignition 12V directly to the SMAKN. The relay provides some protection to the ignition circuit but the direct hookup is simpler. I’ll cover both options.

Relay Circuit Option:

Mount the relay (e.g Novita RL-44 or RL-45) in the electrical bay so you can access its terminals.

  1. Wire 12V from HF-1 (spare mini breaker on control board in rear of the elec. bay) to terminal 30 of the relay.
  2. Wire terminal 86 of the relay to Ign 233 wire (runs to Bird Ign terminal and may be labeled VC05 on 09 coaches). Use a Quick Splice or Wago connector. This is the trigger for the relay.
  3. Wire relay terminal 87 to the fuse holder on the 12V input line of the SMAKN. Connect it to the existing blue butt connector.
  4. Using an eyelet blue terminal, connect a wire to a BIRD relay mounting bolt. Insert a steel washer between the screw head and the eyelet terminal. Join this wire, the SMAKN 12V ground and terminal 85 of the relay together using a Wago connector or wire nut.
  5. You should now have the 2 24V wires coming out of the SMAKN with a blue butt connector on each.

This completes the relay wiring.

Pump relay wiring

Direct Connection Circuit Option:

  1. Crimp a blue fork or eyelet type connector to the 12V ground wire coming from the SMAKN.
  2. Ignition switched 12V power is available on wire ING 233 running to the Bird Ing terminal. Run a wire from Ign 233 (may be labeled VC05 on 09 model coaches) to the blue butt connector on the SMAKN 12V 10A fuse holder. (You can use a Quick splice connector, however the author prefers Wago splices as they are generally more reliable)
  3. Hook the ground to a mounting screw of the relay. Insert a steel washer between the screw head and the fork connector.
  4. You should now have the 2 24V wires coming out of the SMAKN with a blue butt connector on each.

Verify your wiring is correct by attaching a volt meter to the 2 24V wires at the open butt connectors and turn on the ignition. If wired correctly, you will see 24V. Be sure the polarity is correct. 

Mount the SMAKN:

Drill 2 mounting holes in the bottom plate of the electrical bay. Be careful not to leave any drill debris in the bay. 2 #8 pan head screws, lock washers and nuts (w/nylon inserts) are suggested.


Assemble the CAT 155-2270 Connector:

The connector is made up of 3 components; the connector body, the pin receptacles and the wedge unit.

Wires must be attached to the pin receptacles. (I suggest Black for ground and Yellow or White for voltage). Make sure the wire length is sufficient to reach from the electrical bay to the mounting location. I used 5’ to be sure to have enough. CAT uses a $400 crimper so I decided to solder them. The wire will be inserted into the shorter of the 2 ends of the receptacle. Strip the wire to the depth of the receptacle and lightly tin it with solder. Next take a very short piece (~1/8”) of 0.050 solder wire and insert it into the receptacle where the wire will go. Using a solder gun with a clean tip, heat the receptacle to melt the solder while inserting the tinned wire. A jig is needed to hold the receptacle while soldering. I used a finishing nail inserted through a piece of wood.

Assemble the connector by inserting the pins with wires attached into the connector body at the end with the 2 small holes in the rubber boot. Location 1 (marked on the outside of the connector body is the positive voltage position. Push the wire through until the end of the receptacle is even with the opposite end of the connector. Repeat this for the second wire/receptacle. After the receptacles are properly positioned, insert the green wedge into the end of the connector body, pushing it in until it is seated. When properly seated, the 2 receptacles will be aligned with the 2 ports in the wedge.


Mount and Hook Up Filter/Pump Assembly: (Also refer to the CAT Special Instruction booklet)

Assemble the pump on the bench. Insert and tighten the 2 hex socket plugs (180-8071) with O rings, in the unused input and output ports on the sides of the pump. Assemble the Parker 6405-10-8 adapters to the elbows before threading them into the pump body. Apply yellow Teflon tape to the threads of the elbow to prevent leakage and tighten them into the female adaptors. Then thread the adapters into the pump body. Be sure that each adapter has a rubber O ring attached. The lower location on the right side of the pump is for the input fitting and the upper location on the left side of the pump for the output fitting. Place the inserts into the 3 mounting holes and cap each end with a rubber mount.

Mount the pump assembly to the mounting plate using the hardware supplied with the pump. The CAT instruction booklet illustrates the proper arrangement of washers. I chose to add a lock washer just under the nut. Locktite would also work.


Plug the 155-2270 connector into the pump and route the wires back into the electrical bay. Cut the wires to the proper length, strip the ends and crimp them into the 2 blue butt connectors from the converter, observing polarity. The wiring is now complete.

Remove the fuel lines from the OEM filter if you haven’t already done so. A plastic line cutter is handy but you can use anything that will give you a clean and square cut. Be sure to identify the line from the fuel tank as that goes to the input of the pump. You may have to re-route one or both lines to reach the pump location. If so, be careful not to crimp the line(s) and protect the lines from abrasion where necessary. I found that 5/8” ID heater hose worked well for this application. You may need to apply a bit of silicon spray to get the hose to slide easily over the fuel line. Insert the lines into the proper compression fitting ends of the elbows and push it until it locks. If you are not using a locking compression fitting, be sure to install a metal insert (Parker 63PT-10X) into the end of the fuel lines before tightening the nuts.

Turn on the ignition and start the engine. If the glass bowl doesn’t fill with fuel, open the bleed knob slightly to break the air lock and then tighten it. Reinstall any plastic ties etc. The installation is complete.

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