fuel line routing from gastank to carb?

how deep in the tank should the lines b

larry
October 2011

HOW TO CHANGE FUEL LINE ON McCULL0UGH 2014 CHAIN SAWS.

I have successfully changed the input fuel line by purchasing Tygon tubing from a local lawn equipment dealer. I did not see the box he cut this from, but the tubing I bought measures 0.190" outside diameter. I gave him a piece of the old tubing and he matched it up. A 18 inch piece cost me $1.19.

The routing of the fuel line involves three pieces, one piece from the fuel priming bulb to the carburator is 3 inches long, a piece from the fuel priming bulb to the gas tank is about 4 inches long and the piece from the fuel tank is about 7 inches long. The priming bulb sucks air and fuel from the carburator and dumps it back into the gas tank. Therefore, when you press this repeatedly, gasoline will eventually appear in the bulb when the gas line to the carburator is full of fuel. The bulb may not completely fill, there will always be a little air in the bulb.

The fuel line in has a filter on the end within the fuel tank. If you find this has broken off, as I did, you have to turn the tank upside down and shake the filter and any pieces of broken fuel line out of the tank.

Replacing the fuel lines within the carburator compartment is easy if you remove the carburator first. To work on this you must remove the two screws holding the carburator to the engine. You may need to use a small screw Torx driver, although on my chainsaw, there was also a long straight slot on the head. The line from the priming pump to the carburator goes to the left hand line on the carburetor (as viewing from the top with the blade extending away from you. The input line will go onto the right line on the carburator.

The two lines into the fuel tank are located in the middle of the tank left to right and one about 1/2" above the other. The upper hole is for the fuel intake line. The fuel line passes through this hole and a second hole visible within the tank fill hole.
This was the trickiest hose to replace. How I did it was to use a piece of #12 copper electrical wire stripped out of its insulation. This was fed through the 7-inch Tygon tubing piece until it emerged from the far end. I also found it necessary to put a bull nose end on the Tygon tubing in order to get it to feed into the tank hole visible from the tank fill hole. Why? I don't know, but after 20 minutes of trying to feed the hose (both naked and with the electrical wire inside) into that second hole, I gave it a bull nose on the tubing by careful cutting with sharp scissors and using a sanding block. Perhaps McCullough has a special tool to do this, but a call to their 800 number could not get a knowlegible answer from the parts person.

After the Tygon tubing shows up in the tank fill hole, I pulled it further with needle nose pliers and was able to pull the copper wire back out of the tubing. I then cut the bull nose lead I put on the Tygon tube and installed the filter onto it. I found that a little oil on the nozzle and the carburator lines makes the tubing easier to slip on. The stuff the filter and Tygon tubing back into the tank fill hole and towards the front end of the tank so that it drops into the bottom portion of the tank. After attaching the intake line to the carburator, use the needle nose pliers to pull excess line into the tank.


Reassemble the carburator to the engine and you'll be good for another 10 years of happy chainsawing!

Bud Taylor
May 2009