How to Remove Varnish in a Fuel System

Written by katrina matterhorn
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Fuel varnish in a fuel system is the result of the build-up of fuel. This is not uncommon. It can create problems with the efficiency of the machine because the varnish can create impediments to the fuel's travelling as quickly as is needed. It can also cause a machine to run lean and possibly incur piston damage. You can clean out the fuel system thoroughly in a few days.

Skill level:

Things you need

  • Nozzle
  • Water hose
  • Dish detergent
  • Buckets
  • Muriatic acid

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  1. 1

    Confirm that the fuel system is completely empty of fuel before you attempt to clean it.

  2. 2

    Remove the fuel system from the machine. Read the user's manual to detach the fuel system properly.

  3. 3

    Put detergent inside the fuel system and spray it with water from a hose. Set the hose nozzle to the highest setting to remove caked on varnish.

  4. 4

    Let the fuel system dry for 24 hours. You can also use a hair dryer if you wish to speed up the drying process.

  5. 5

    Use duct tape to seal the holes where tubes connect. Don't cover the gas cap opening. Put a cup of muriatic acid into the fuel system and shake it around until the system is completely coated. Let the acid sit for 24 hours to loosen any excess residue.

  6. 6

    Pour out the muriatic acid. Remove any duct tape. Let the fuel system dry for 24 hours or dry it with a hair dryer. Reattach the fuel system to the machine following the user's manual.

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