If your car struggles to accelerate, especially on the highway, or there are other signs that the engine is not receiving enough fuel, then the fuel lines, filter, pump or injectors may be partially clogged. If the engine does not start at all, here are some simple methods to check what is causing the malfunction.
Steps
Method 1 of 2: Electricity Test
Step 1. Check the fuel pump fuse
The problem is sometimes not a malfunction of the pump, but an interruption of the energy that powers it. Consult your vehicle's maintenance manual to find the fuse box and locate the one protecting the pump. Take it out of its housing and check for any damage; if it is broken or burned then it means it is no longer functional. If it seems to you in perfect condition, check the rest of the fuses that are connected to the fuel system and, if necessary, make the necessary replacements. If all fuses are OK, then ask a friend to start the engine while listening for the "click" of the relay engagement.
- If you need to change a fuse, check that the new one has the same electrical current rating - do not install any never one that is rated with a higher number of amps.
- If you have found a broken fuse, be aware that there may be spikes in current and you should check the various circuits. Replace the blown fuse and try to start the vehicle once more; if the fuse blows again, you are faced with a short circuit that needs to be evaluated by a professional. Take the car to an auto electrician for the necessary checks.
Step 2. Check the electrical voltage of the pump
Even if the electrical system emits energy, it does not necessarily reach the pump, so you have to check the voltage on this element. Again, read your vehicle manual to understand where and how to take the measurement.
Check the source of the potential difference to see if the electrical energy coming out of the fuse is reaching the pump. If the latter is not receiving power, then check the pump relay circuit, as the problem could be the relay itself
Step 3. Check the voltage drop with a voltmeter
Make sure the power cable shows full voltage and the ground cable confirms that it is well connected. If this test does not indicate any malfunction, the damage is likely to be borne by the pump which means that you will need to replace it, although you can proceed with other more thorough checks by testing the pressure.
If the voltmeter detects more than 1V of difference, you may have a corroded wire problem or an abnormality in the positive or negative pole. Take the car to the mechanic for some advice
Method 2 of 2: Pressure Test
Step 1. Rule out the possibility that the problem is the filter
When this element becomes clogged with fuel sediments, the car has difficulty accelerating and you may suspect some damage to the pump. To check the filter, remove it and drain the excess gasoline inside it. Slip a segment of rubber hose into the fuel inlet opening and blow - but be careful not to blow too hard, as the resistance from the filter may be minimal. Check the piece for debris and clean it by blowing into the fuel outlet port so that the dirt falls onto a white cloth.
Step 2. Get a gas pressure gauge
You can buy it in auto parts stores for 20-30 euros and it will prove useful for checking most car models and brands. If you don't want to buy this tool, you can borrow it from a mechanic or shop. The test will only take a few minutes.
Step 3. Attach the pressure gauge to the inspection valve
This is usually located near the injectors. First of all, identify the point where the pump connects to the filter of the common duct; there should be a separation joint or test nozzle here, where you can attach the pressure gauge.
Different models of pressure gauge may have different instructions for use, while the position of the inspection valve may change according to the machine. For all these reasons it is always advisable to rely on the user manual
Step 4. Ask a friend to rev the engine while checking the gauge
Wait for the engine to warm up a bit, then repeat the test both while idling and at higher speeds, depending on your pump specifications. If you don't know what the test speeds are for your vehicle, simply accelerate and observe how the values change: if your pump has a serious malfunction, the gauge needle will not move or reach the expected values indicated in the manual d 'use; this means that the fuel pump will have to be changed.
The pressure values you detect must coincide with the specific ones listed in the manual and should increase as the engine increases in rpm. If this doesn't happen, you need to replace the pump and filter
Advice
- Always take the right safety precautions when performing tests and checks. Have a fire extinguisher handy while you work on the fuel system.
- If you need to replace the pump, be aware that remanufactured ones are just as good as new ones and are much less expensive. You can also purchase kits to rebuild some parts if you're feeling brave enough to try. You can disassemble the fuel pump with a screwdriver and reassemble it yourself, following the instructions enclosed with the kit. If this solution doesn't appeal to you, then ask your trusted mechanic to find and fit a remanufactured pump for you. You should still have at least a 3 month warranty.
