A blocked fuel-pump filter will cause the engine to cut out intermittently, mainly at excessive speeds, and it can forestall altogether. Not all motors have a clear out out in the pump. Later models often have sealed, filterless pumps which do not need maintenance, and rely on filters elsewhere, mainly in fuel pipes or the petrol tank, or on the inlet to the carburettor float chamber.
Many motors have a mechanical gasoline pump driven off the camshaft. The pump need to be evidently seen on one facet of the engine. If now no longer, hint the gasoline pipe returned from the carburettor.
If the fuel pipe leads away from the engine towards the gasoline tank , you can have an electric fuel pump. Often that is in the back of the auto, near or immersed in the tank. Disconnect the battery before servicing an electric pump – an accidental spark may want to ignite spilled petrol. Clean all filters via way of means of washing them with fresh petrol. Wipe out the interior of the pump with a easy lint-free rag.
Make sure sealing gaskets are sound. Replace them if necessary. There will also be a sealing washer under the fixing screw. Do now no longer overtighten the screw(s) of the pump cowl or it’s going to leak and harm the pump. If the knob keeping a pitcher dome is overtightened, the dome may also break.
Many electric powered pumps are SU, or copies built under licence. They are often in awkward positions, but must be removed to easy the filter. Have old pencils or rubber bungs handy to stop petrol gushing out of the disconnected gasoline pipes.
Note which pipe is which – the same applies for electrical connections. There can be one or , relying on whether or not or now no longer the pump is earthed directly to the car body.
Filters fitted to most mechanical pumps
Most mechanical pumps have a removable top covering the filter. On earlier units the top may be a glass dome. A central screw or nut holds the top on. Unscrew this, lift off the top and take out the filter. If a flexible fuel pipe is connected to the top, leave it there. This will ensure that you refit the top to the pump the right way round.
Some pumps have a cylindrical filter attached to the cover, which screws by hand into the pump. Some may also use crimped-on pipe clips; snip off with side cutters and replace with a screw clip if the pump is removed.
SU electric pumps
The most common SU electric pump has dome-headed right-angled ‘elbow’ inlet and outlet nozzles. They are made of black plastic and mounted side by side, but leading in opposite directions.
Which one does which process is marked at the casing. Remove only the inlet nozzle and work quickly, due to the fact the rubber sealing ring below it swells up when exposed to the air for a time.
Do not remove the filter – clean it by brushing dust away with a clean, small paintbrush and clean petrol. Check that there are no loose bristles in the brush. Take care to refit the nozzle the right way round. Earlier SU pumps have screw-in connections set up almost at proper-angles to every other. The clear out out is below a large brass-headed cap opposite the outlet to the carburettor.
Two other SU electric pumps are found on larger cars. Both have inlet and outlet pipes side by side. One has a double electromagnet – the large black cylindrical part. To reach the filter on either type, you have to remove the magnet cylinder from the base.
On the double type, remove only the cylinder that is placed at the proper as you view the pump, with the word ‘top’ moulded into the base facing you and the right way up. Take out the six screws holding the pump together, and separate the cylinder and base. On the bottom, greater screws hold a metal plate over the valves. Unscrew them and take out the inlet-valve cover and valve – the outlet valve is marked ‘out’ at the out of doors of the bottom.
The filter, a small gauze disc between two rubber seals , is underneath. Prise it out gently with a pin. Be sure to reassemble the pump correctly – the valve goes back with the straight strip on top. Check that the gasket between the main parts of the pump is sound, but do not turn it. It must remain in the same position for the pump to work. Refit the pump, and the two electrical connections and reconnect the fuel pipes.
SU mechanical-pump filter
An SU mechanical pump is different from other types and is found mainly on British-built cars. There are main SU types: AUF 800 which has a filter, and AUF seven hundred which does not – although its top is removable.
The 800 has inlet and outlet pipes side by side on top, leading in opposite directions. The right-angled ‘elbow’ connectors are held in place by a steel ring fixed by screws. These screws are often very tightly seated, and also are made from gentle steel. Use a correctly fitting screwdriver in good condition to remove them.
Remove the ring, lift off the inlet elbow only, and lift out the filter. Clean it and reassemble quickly: the rubber sealing ring under the pump elbow swells up when it’s far exposed to the air.
Using a Fuel System Cleaner
Read the instructions on the bottle. While most fuel system cleaners work in roughly the same ways, there are differences from brand to brand. Read the instructions on the fuel system cleaner you purchase thoroughly to ensure you follow the right steps.
- You can purchase fuel system cleaner at many large retail stores as well as all auto parts stores.
- Purchase fuel system cleaner, not injector cleaner. These products are similar but serve different purposes.
Run the engine until you’re nearly out of fuel. Most fuel system cleaners are meant to be poured into an empty fuel tank so it can mix with the fuel you add to it after. Run your engine until the fuel gauge reads as empty or “E.”
- The tank doesn’t need to be completely empty and free of fuel. It just needs to be as low as possible.
Pour the contents of the fuel system cleaner into your gas tank. Open the bottle and puncture the plastic seal beneath the lid. Then insert the spout of the fuel system cleaner into the gas filler neck of your vehicle just like you normally would with a gas pump.
- Most fuel system cleaners come with enough for one treatment. If yours comes with more than that, read the instructions to determine how much of the bottle to add to your tank.
- Gloves aren’t necessary for this task, but you may want to wear them to keep any fuel system cleaner from getting on your hands.
- If you get any of the fuel system cleaner on your hands, wash them with soap and water.
Fill your tank with pump gas. The new gas you pump into the fuel tank will mix with the fuel cleaner already present. This will ensure the cleaner is properly dispersed throughout the fuel and will also help the pump to begin picking up fuel with the cleaner in it right away.
- Fill the tank all the way with new gas.
- Use the same octane fuel you always use.
Start the engine and let it idle for a few minutes. The fuel system cleaner will flow through the fuel pump and filter on its way to the engine where it will burn along with the gas. As it passes through, it will begin to break down deposits of sediment in your fuel pump and throughout the rest of the system.
- Many fuel cleaners recommend letting the engine idle for ten or fifteen minutes to start letting the fuel and cleaner flow through the system before you start driving the car again.
- After that initial stage, you can drive the vehicle like normal as it cleans your fuel system.