How To Clean And Renew Fuel Pumps In A Car Engine
Mechanical pumps contain a filter to prevent grit being passed to the carburetor. The filter should be cleaned at major service intervals every 10,000 or 12,000 miles. Below are steps to be taken in cleaning the mechanical fuel pump:
- Disconnect the battery.
- Place a piece of cloth under the pump to catch spilled petrol.
- On pumps with a glass bowl, slacken the screw at the top of the wire retainer, swing the retainer to one side and lift off the bowl.
- On later pumps, a metal cover is used. Remove the center screw and lift off the cover. Lift off the wire mesh filter and wash it in petrol.
- Dip a clean paint brush in petrol and remove any dirt from the sediment chamber, then wipe clean.
- Refit the filter and glass bowl or cover. Make sure that the sealing ring is in good condition.
- Tighten the bowl or cover screw just sufficiently to compress the sealing ring and form a petrol-tight seal. Reconnect the battery, run the engine and check for leaks.
How to renew a mechanical fuel pump
- Disconnect the battery.
- Remove the fuel pipes at the pump. Plug the end of the inlet pipe with a pointed pencil to prevent fuel leaks.
- Undo the nuts or bolts holding the pump to the engine.
- Withdraw the pump. If the pump is operated by a short push-rod, pull out the rod.
- Clean the remains of any gasket from the pump mounting area with a scraper. If there is a spacer between the pump and engine, take care not to damage the spacer surface when removing old gasket material, otherwise oil leaks may occur.
- Fit new gaskets on both sides of the spacer and offer up the new pump, taking care that the operating lever fits over the camshaft.
- Fit the fixing nuts or bolts, screwing them in finger-tight. While the pump is still loose, push it towards the block. If it is fitted correctly, the spring inside will press the pump away from the block. Provided this happens, tighten the fixings. If there is no spring resistance, the pump lever has been pushed underneath the camshaft and will not operate. Remove the pump and try again.
- Where the pump is operated by a push-rod, fit the rod and then fit the pump using new gaskets. There is no need to carry out step 7 above for similar pump.
- Remove the pencil from the fuel pipe and refit the unions to the pump, taking care not to cross-thread them.
- Reconnect the battery, run the engine and check for leaks at the pipes.
HOW TO RENEW AN ELECTRIC FUEL PUMP
Depending on the car, an electrical fuel pump will be mounted under the floor at the the rear, inside the boot or under the bonnet.
As different types of pump are used, depending on their location, it is important to quote the make and model of car, and engine and chassis numbers when ordering for a replacement. Below are the steps required for its renewal;
- Disconnect the battery.
- Depending on the location of the pump, either raise and support the rear end of the car, lift the bonnet or remove a trim panel in the boot to gain access to it.
- Release the pump fixing clamp and lift the pump clear. If a plastic pipe is attached to the end cover, detach it.
- Disconnect the live cable and remove the earth wire from the pump body.
- Undo the fuel pipe clips and disconnect the pipe which comes from the tank. Block the end quickly with a pencil-point to prevent fuel leakage. Remove and block the other pipe with a pencil.
- Fit the new pump to the clamp, ensuring that it is at the correct attitude.
- Reconnect the live feed and earth wire; correctly fit the fuel pipes (one pipe stub on the pump will be marked ‘inlet’), and if necessary, reconnect the breather pipe to the end cover. Reconnect the battery and switch on the ignition to test the pump, it will click for several seconds as it fills with petrol.
- Lower the rear end of the car, if necessary.
