How to test fuel pump relay without multimeter

 

Some high-end or luxury cars may cost more to repair. Then connect the other two leads to 12V+ and 12V- on your battery. How It Works. CASE 2: The engine did not start, not even momentarily. Really the one and only way it should be tested. 6 Is Getting 12 Volts. May 22, 2022 · In any case, the first step would be installing a fuel pressure gauge and verifying the pressure with the pump running and when trying to start the engine. When the ignition is turned on it activates the fuel pump relay and Check the wire that provides power to the fuel pump itself by attaching a multimeter to the positive wire running from the fuel pump assembly mounting plate to the fuel pump. Visual Inspection. In this video I will show you how to troubleshoot this entire fuel pump electrical system, including the fuel pump relay, wiring and computer. Most cars apply voltage to fuel pump for about 3 sec. A remote-type relay usually sits near the battery, on the fender well, and the red battery cable connects directly to it. If resistance over that fuel pump is dead. 6. 3. Now, connect the multimeter. TEST 2: Making Sure That Terminal No. Fuel pump power wire on 95 is gray. There should be less than 5 ohms for this test. 5. The fuel pump is OK. Airtex is committed to providing the most up-to-date, in-depth fuel Jun 27, 2011 · 1. This connection provides direct power to the fuel pump. The multi-meter tool should make a beeping sound every time you do this. What the actual voltage is supposed to be I don't know because I have an 08 where manuals do not exist. Oct 21, 2022 · In this video we explain how to test a relay with a multimeter in just one minute. First I will show you a known good pattern, then I will simulate a no compression problem in one cylinder by removing a spark plug. Finally, I will show you how to synchronize the starter current waveform with an ignition firing event in order to Here are some common symptoms of a bad fuel pump relay: #1. The reason your 4. If the fuse is fine, your reading should be exactly the same as without the fuse. How To Fix Fuel Pump Relay Problems in Honda Rancher 420. 4. this video shows how to tell if the fuel pump is bad in your car,you how to measure fuel pump relay and cir Mar 29, 2021 · 1. Step 4: Test the Fuel Pump Relay. Make sure the EEC relay is good. 20- How to test a relay switch for a good complete circuit, and not just for a clicking sound. * You did this already and heard nothing. Visually inspecting the fuel pump relay can also provide valuable clues about its condition. to/2aOl1e8Dew Nov 8, 2023 · Quick Summary: To run a fuel pump directly to a battery, remove the fuel pump relay and directly connect the sockets for relay pins #87 and #30 using a small piece of around 12-gauge wire with connectors on its ends. When the coil is energized with power, the resistance between the NO pins is expected to be very low. 🧽 Step 2: Check and Clean the Connectors. This tells you the low current circuit of the fuel pump relay is getting juice and this is a good thing. Step 4: Use a multimeter set to the continuity or resistance mode to test the relay. Apr 11, 2008 · Jeff, the relay operates by receiving signals from the ICM. With the relay in the configuration that has the 2 load pins connected, place the test voltage on 1 of the load pins of the relay and an automotive test light on the other load pin of the relay. The oil pressure switch would have to be shot and not working for the relay to effect the running. Jumper wires should be used to supply 12v power to terminals 86 and 85. then find the one that comes from the ignition switch. Check for voltage at the pump with a meter. Separate the positive and negative circuits. Then, connect the negative lead to a suitable ground point on the vehicle. Go to: TEST 2: Checking For Power (High Current Circuit). to/3PPZNzP Insulated Glo May 16, 2024 · Step 3: Inspect the Relay. This method is called ‘Fuel Pump Relay Bypassing,’ as it bypasses the relay so that the fuel pump connects to the battery Nov 26, 2011 · fuel pump connectors usually have 4 wires, thicker ones for pump, thinner for fuel level gauge. Fuel pumps are very simple machines, its a DC device so if you reverse the wires, the pump will pump backwards. 5. Ve Connect the red probe to the ground wire and the black probe to any ground terminal. Method 3 (part of the way like Method 1) – an alternative option if Method 1 is not possible. I cover 3. It starts but that ether isn't enough to make the engine stay on. One More Thing…. It's the 4th from the left on the bottom row of relays, under the dash. Remove the 5mm Allen bolts securing the fuel pump assembly to the tank, and lift out the fuel pump Oct 14, 2023 · Open the hood and locate the power distribution box (PDB) near the battery. Make sure it is on DC and have somebody turn the key. 00 - 0. You’ll still want to test that your relay is delivering the correct voltage on the Even if you don’t hear the relay click, it may not mean that the relay has failed, but you can connect and disconnect the terminals a few times to make sure you can’t hear it click before moving on. If you set your multimeter to Ohms, and touch the probe to the terminal 87 contact, you should see a few Ohms resistance due to Jan 16, 2012 · The fuel pump relay's low current circuit (wire 2) is getting power (TEST 1). Feb 12, 2023 · Test the fuel pump with a multimeter. 4) Test the fuse location with a test light or mutimeter to see if there is 12V+ when the key is on. 2. Step 3: Split the +&- circuits. That the fuel pump does come on and is producing the correct fuel pressure specification (35 to 45 PSI) (TEST 3). Feb 10, 2013 · Here is how you test a car relay the correct way. Now, locate the fuel pump relay’s power supply pin, which is usually labeled as “+12V” or “B+” on the relay. II. Some simple tests a Step 3: Install the New Fuel Pump Relay. 5) Check fuel pump relay. Aug 24, 2010 · Also check the connection at the back near the gas tank that plugs the fuel pump into the rest of the wiring harness as they corrode. This is the easiest way to do it out of the car and t Sep 4, 2020 · how to tell if the fuel pump is bad in your car. Start by disconnecting the fuel pump relay from the wiring harness. You can really test the reliabilty of the relay. ⚡ Step 6: Test the Relay’s Voltage. Check the circuit, if necessary. Your fuel pressure gauge will register one of the two following results: 1. You also need to make sure the fuel pump relay is good. Leave the battery connected, and you can now connect terminal 30 to the battery’s positive terminal. You need to open the hood of the car and start looking for the relay, which is usually located in the fuel pump. Place a shop towel around the fuel filter's banjo bolt. another one should be ground and the last one is going to the pump. To perform electrical tests, you will need a multimeter. You should be able to hear the gasoline pump activate. Connect the power supply: Connect the power supply wire to the terminal labeled “power” or “battery. 2Ω and 0. Engine Stalling or Not Starting. You should hear a click, and the resistance should drop to 0 on the voltmeter. Corrosion. 2. These pins are usually labeled with numbers or letters. Set the volt meter to Ohms (measures resistance), and connect to terminals 30 & 87 (double check this). The meter will apply a small voltage to make the semiconductor conduct and read that voltage on the screen. Failure: A faulty relay may fail to break the circuit when the vehicle is off, causing the fuel pump to run continuously. Guess you'll need to get to the bike, and look at the wire connector, unless someone else chimes in. You want to use either a 12V battery or power supply to test the relay. Jan 16, 2012 · CASE 1: Your multimeter showed battery power. After installing the new fuel pump relay, start the engine to test it. Confirm the current carrying ability of the load connectors. Mar 10, 2019 · This video shows you how an automotive relay works and how you can test it using an digital multimeter. Now, connect the fuel pressure test gauge to adapter to the fuel filter's banjo bolt. Test with a Multimeter. ) The fuel pressure gauge will register 35 PSI, or. You can also use an electrical cleaner and a blower to blast dust off. Electrical Tests. 1. On average, the Total replacement cost, including labour, is from $65 to $80. Nov 4, 2020 · PGM-FI Main Relay Pin Out. It helps to think of a relay as a regular switch, like the one you use at home to turn on and off the lights in a room. 🔔 Tools used in video: Multimeter: https://amzn. The relay will close, and you should get continuity between the two pins that the meter is Nov 1, 2014 · Here is a video on how you can test a Relay with or without a diagram. The pump uses the gasoline as both a lubrican Jul 10, 2023 · Step 7: Test the Voltage. Mar 29, 2023 · Follow these steps to test the fuel pump with a multimeter: Locate the fuel pump relay in the fuse box or relay panel. 1995 Chevy Astro 4 3L The procedures shown in this video can be applied to a wide variety of GM vehicles over many different model years, that are using a di Fuel Pump Control Module ReplacementIn this video shows how to diagnose and replace a bad fuel pump control modulecommon signs:engine won't startno electric Aug 14, 2020 · You can check and see if fuel pump is getting power there. Dec 13, 2023 · And if the multimeter reading is not zero, the relay is bad. Step 2: Remove the fuel pump relay from its socket. Check For Load Circuit Resistance Between 0. To see if you have electricity, turn off the battery and use a test light on terminals 87 and 30. If that does not happen, your fuel pump relay is either broken or burned out. Oct 24, 2019 · I show you how to quickly and easily test the fuel pump in your car or truck!Instagram: smoked_out_garage Nov 16, 2010 · 1. The multimeter should read 12V in the live wire in a fine fuel pump. Fuel flows when relay socket is correctly jumpered. In this video I will be showing you how to use starter current to determine cylinder compression. First, clean the fuel pump relay prongs with a wire brush to eliminate dust, rust, and corrosion. The first step is to verify the problem is fuel related. Learn how to locate and test the Fuel Pump Fuse and Fuel Pump Relay on your 1995 and 1996 Ford Ranger! If you're having issues with your vehicle not starting Nov 27, 2009 · You need a couple test leads and a volt meter. Set the multimeter to resistance mode (ohms). Attach the probe to the tester and check the reading on the multimeter. It is not difficult to test the relay of a fuel pump. You can unplug it and test the fuel pump by connecting a wire to the fuel pump’s positive terminal and the car battery’s positive terminal. To know how to check the fuel pump relay with a multimeter, you need to find it in your car for a quick analysis. This article will delve into the nitty-gritty of testing a relay using a multimeter. Remove the relay and have some one switch on the ignition without starting the engine. If the EEC relay is bad, the EEC won't turn on. Step 4: Set the multimeter – set your multimeter to the resistance or continuity mode. One of the most common symptoms of a bad fuel pump relay is the engine stalling or not starting at all. • Stress Loaded Test Light • Using the Stress Loaded Test Light • Building the Stress Loaded Test Light • Fuel-Pump Relay & the Stress Loaded Test Light • Dual Polarity & 5 Volt Reference Test Light • Amplified Sensor Tester • Injector & Coil Magnetic Detector • Fuel Injector Pulser • ECM-ECU Memory Saver Tool• Loaded Nov 14, 2023 · In general, there are 3 main steps to test a fuel pump with a multimeter: Look for open or closed loops. Touch the power supply's hot lead to the input pin. Turn off the power supply to the circuit where the relay is connected. Nov 5, 2012 · Ground your black multimeter wire and use the red one to probe each contact looking for 12 volts. First, unbolt the fuel tank and then lift it off the motorcycle. This is because the fuel pump relay is responsible for supplying power to the fuel pump, and if it fails, the fuel pump will not be able to provide Jan 26, 2010 · Step 5 - Testing Pump Relay. Apr 20, 2012 · This video is about how to test for voltage drop that might effect fuel pump performance. Perform a thorough diagnosis to ensure the pump is the problem before replacing it. Step 3: Inspect the relay for any signs of damage, such as burnt or corroded terminals. Find the fuel pump relay, which is usually labeled on the cover or the relay itself. Fuel is needed by the combustion engine to run, and the fuel pump relay ensures there is never a dearth of that to the engine. My Cheap Multimeter in the video: http://amzn. Have someone turn the ignition key to the “ON” position without starting the engine. You can buy fuel pump relays from any automotive spare parts shop. Engine does not fire when sockets are jumpered and engine is cranked. Ensure that 12v+ power is sent to the fuel pump. 3. Save time and money just Shop for New Auto Parts at 1AAuto. 2 Is Getting Ground. If the engine won’t start: Sep 21, 2022 · Test for power supply: Set your multimeter to the voltage setting and connect the positive lead to the battery’s positive terminal. It can be the same as the voltage on the battery (mostly 12 volts). Mechanic's Assistant: What's the year and model of your Hyundai? May 6, 2023 · 7. Take it to a local mechanic for more support. Replacing a fuel pump without testing it is an expensive mistake. Feb 15, 2019 · About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright To check the relay coil's resistance, take the multimeter you have and place it in the ohmmeter (Ω) setting and place the probe leads of the multimeter on the 2 terminals of the relay's coil. Turn on the ignition switch and replace the relay. #8. Resistance isn't polarized. . Part 1: Check whether the problem is fuel-related. For best results, experience reality in moderation. Jun 6, 2012 · Sep 5, 2014. The opposing contact will go to the load (fuel pump) and is terminal 87. Then, you can do additional testing to find out if the pump is to blame. Lift it and check under it for the numbers 30, 85, 86, and 87. The multimeter showed 0. How to tell if your car's fuel pump is bad and needs repair. Remove the relay and inspect it for any signs of damage or corrosion. If either one is bad, it will produce the same no-start symptoms. The vehicle being tested is a 1999 Chevy Suburban with no fuel pressure. Test the fuel pressure through the port on the fuel injector rail. If the fuse test comes back negative, you should move on to the fuel pump itself. Nowadays, online platforms are making it easier for buyers. Jul 8, 2023 · Here are the steps to follow: Identify the relay terminals: Refer to the wiring diagram or your vehicle’s manual to identify the correct terminals for the power supply, ground, fuel pump, and ignition. TEST 1: Making Sure That Terminal No. TEST 4: Making Sure That Terminal No. Every car has relays, but why? what do they do? and how can we check if a relay is bad? Understanding relays Mar 8, 2023 · Here’s a step-by-step process to test the fuel pump relay using a multimeter: Start by turning off the ignition and disconnecting the negative terminal of the vehicle’s battery to ensure safety. It is generally controlled by the Powertrain Control Module (PCM) or the ignition. Nov 8, 2023 · Here’s a summary of your 3 options: Method 1 (one-wire relay bypass) – easiest, quickest, and safest. Check for signs of corrosion, damage, or loose connections. 4. If there is 12V+, go to step 6. 0L Ford vehicle is not starting is due to another reason. Aug 31, 2023 · Step 3: Identify the relay pins – take a closer look at the relay and locate the pins. This fuel pressure gauge result lets you know that the fuel pump is working and delivering enough fuel to the fuel injectors. 4 and 5 pin relays and all you need is a 12v source, a multimeter and a test Dec 31, 2020 · Explaining How relays work and How to test them. Jun 13, 2024 · Open the hood and locate the solenoid — the small cylinder on top of the starter motor. Aug 8, 2023 · The fuel pump relay is usually labeled and can be identified by its unique shape or number. The fuel pump relay acts as a switch that directs power to the fuel pump. Testing The Fuel Pump. Remove the fuel pump relay from its socket. Jan 20, 2024 · Fuel Pump Relay Replacement Cost. it would just have a long crank before starting. Identify the coil and contact pins on the relay. Check for voltage at the relay connector using a digital multimeter. Next, remove the fuel tank by taking the pivot bolt at the rear of the tank off, then disconnecting the electrical cable, the fuel line and twin breather lines beneath the tank. 💡 Step 5: Connect a Test Light. The fuel pump relay's high current circuit (wire 4) is getting power (TEST 2). How to check a fuel pump in your car DIY with Scotty Kilmer. Find the wire (circuit) that feeds power (12 Volts) to the fuel pump and with a multimeter in Volts DC mode, verify that 12 Volts are reaching the fuel pump when you crank the engine. Step 2: Turn on the engine. Unfortunately, when you turn key to on, fuel pump only primes for a couple of seconds. Without starting the engine, turn on the ignition again and Feb 23, 2024 · The first step is to visually inspect the fuel pump relay. If there’s no reading on the multimeter, it’s an indication that the fuel pump is faulty and needs to be replaced. Also I think that the fuel pump relay can be swapped with ac relay beside it to Turn off the relay and turn on the ignition, but do not start the engine to connect battery power. Set the multimeter to the voltage measurement mode. . Regards, Dec 29, 2012 · 1. Watch this video of how to test the fuel relay for resistance. Remove the cover of the PDB to access the relays. Engine Runs Rough at Idle. The fuel pump relay is the one closest to the brake master cylinder. Take the multimeter and attach it to a ground. Connect your ground connection on the power supply to the ground pin on the relay. May 6, 2020 · Learn how to diagnose a failed fuel pump in this video! Andy shows you some diagnostic steps you can take if your engine won't turn over, and you think fuel Sep 28, 2022 · To troubleshoot fuel pump relay problems in the E46 M3, it is important to check the wiring connections, inspect the relay for any signs of damage or corrosion, and test the relay using a multimeter. The test mentionned in the manual all invovle applying voltage to the pins so you may only be able to do the test in the bike unless you have a 12v power supply. Remove the fuel pump relay and connect the multimeter probes to the relay terminals. Testing your fuel pump relay should be the next step after you have noticed any of the symptoms described above. Jun 5, 2023 · Don't have the big fancy tools!? Don't worry, I got you in this awesome life hack for testing your relays! May 31, 2009 · Learn how to test a fuel pump using this Step-by-Step Guide. Locate the fuel pump relay in the vehicle‘s fuse box. Remove the 6mm bolt located on top of the fuel filter's banjo bolt. Remove the relay from its socket or disconnect it from the circuit. Then, prepare the multimeter for the appropriate resistance measurement setting. If there is not, go to step 5. Pull the relay out and using a test light check the terminals for the 12v from battery 1st. You will need to have an assistant to turn key to on, with you under the car with a 12 volt test light or multimeter set to DC volts. If the fuse is broken, you will get no reading, or the multimeter will indicate that there’s an ‘open loop’ (O. Fixes: This issue can be solved by replacing the defective relay with a new one. Remove the red probe from the live wire and connect it to the ground wire. 📏 Step 3: Grab Your Multimeter. )Pull out Fuel Pump Relay 3. Step 6: Remove the fuel pump. Test the voltage just at the switch connection with a multimeter. Sep 23, 2022 · Relays and wiring can be a real pain, and the whole process of testing and diagnosing can be daunting. Now, put a test lead on each end of the fuse. to/c/4/H/electrical-auto-partsLearn how to diagnose a failed relay in this video! So, your horn won't honk, Feb 21, 2023 · The fuel pump relay is an essential part of the combustion engine. Step 4: Connect the multimeter. Put the relay back so you can reach the pins with a multimeter while you cycle the ignition. The electrical resistance should be about 1 ohm. TEST 3: Making Sure That Terminal No. If you find these numbers, you can put the fuel pump relay back. Sep 7, 2009 · Fuel Relay A Brain Beer 1. These pins are typically labeled as “30,” “87,” “85,” and “86” on the relay itself. Familiarize yourself with the pin layout to ensure proper testing. Also, check the continuity in the fuse. The car will struggle to attain its full power. 01 indicating no power. ). Oct 3, 2007 · Sorry I don't have the relay pinout either I would use the wire colours. Just because your relay’s switching function works doesn’t mean that it’s good. Replace relay and Test the fuel pump connector at the back of the car Sep 13, 2022 · It almost starts when we spray ether into the fuel injectors. The fuel pump in a fuel-injected vehicle is mounted inside the gas tank. )Connect Red Wire to (+) and Black Wire to (-). If everything seems to be working as it should, there’s another problem you are missing. It’s a major job to replace it and these pumps are expensive. Test the continuity of the gauge’s wiring and check for any loose connections. Mar 18, 2011 · No fuel coming out of the fuel line further confirms a bad fuel pump. Engine Performance Diagnostics chapter 3 page 26. Aug 10, 2023 · How to test a fuel pump relay without a multimeter? If you don’t have a multimeter, you can still test a fuel pump relay using the following method: 1. Step 5: Find the pump relay. )Locate the Fuel Pump Relay 2. You need to find the relay. Then jump the 12v from battery to the fuel pump itself. 5Ω. Jul 9, 2012 · As for making a fuel cuttoff relay from scratch it will be a complicated design for two reasons. Locate the relay, which is usually situated in the engine bay fuse box or near the fuel tank. Ascertain that it is securely fastened. 🔋 Step 4: Energize the Electromagnet Coil. Carefully remove the fuel pump relay from its socket. Carefully remove the relay and examine it for any visible signs of: Damage. If the EEC won't turn on, the fuel pump relay won't get grounded and won't turn on. L. It doesn't matter which probe is placed on which terminals. It gets this ground from the spark unit when the engine is running. com http://1aau. No fuel flowing when key is in no2 position. ) Jan 1, 2013 · CASE 2: The fuel pressure gauge registered the correct fuel pressure specification. The power for the fuel pump comes from the vehicle’s battery and is switched on and off by the relay. This truck had a new fuel pump installed and still did not have fuel pressure. Before you start making any tests, pull out the relay and visually inspect the terminals and socket for signs of corrosion and overheating. 1 Is Getting 12 Volts. No fuel flowing when key is in no2 position and a known working fuel relay is substituted for the existing one. 5 Is Getting 12 Volts. Method 2 (all the way) – best avoided. Disconnect the fuel pump relay, taking care to not break the plastic tabs. You can further confirm that the relay is bad by taking a multi-meter, put it in diode test and checking across A1 (+) and A2 (-). The red wire is on the passenger side near the fuel pump relay. A relay works in a similar way, but instead of you reaching into the relay to flip on the internal switch directly, you energize a control circuit that connects to a coil inside the relay—this happens to the fuel pump relay when you turn the ignition About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright Mar 24, 2022 · With the fuel pump relay removed, install the fuel pump relay tester. Turn key and listen for it to make a noise. Perform this test for continuity or if the current flows through the relay. Connect the fuel pressure gauge to the Schrader valve on the fuel rail. This is a very easy and quick test for a half-way competent shop and will at least tell you if the issue is related to the fuel pressure. Establish the location of the fuel pump relay on the dashboard or the engine compartment. Fuel pump test. Here is a video on how to test a fuel pump relay. Jan 25, 2010 · Step 5 – Testing the Fuel Pump Relay. Oct 2, 2020 · TEST NEW FUEL PUMP & SENDING UNIT BEFORE INSTALLING. Next, measure the resistance of the sending unit and compare it to the manufacturer’s specifications. Step 1: Check for closed or open loops. Rocksolid Jun 9, 2021 · Checking the fuel pump relay with a multimeter. If you notice any of these issues, you may need to replace the relay. If you want to explore how these steps work, I highly suggest you read through this guide’s Place Probes On Normally Open Pins When Energized. You would have to just replace it to find out. You should hear the pump make a humming sound, indicating that it’s The 4-pin design refers to the number of connector pins on the relay, which are used to connect it to the vehicle’s electrical system. Then start the engine. It has a redundent power feed through the oil pressure switch and doesn't even need a relay to run. Corrosion prevents proper current flow, and overheating indicates problems with the relay or circuits it connects to. Voltage goes to pump directly from fuse 28. If you simplify it and break it into pieces, it's not Apr 7, 2024 · First, locate the fuel gauge and sending unit in your vehicle. It's not enough to just turn the key. Place the multimeter probes on the NO pins with firm contact and check the meter for a resistance value. Apr 14, 2015 · 2. The shop towel's job is to absorb any fuel that may leak when doing step 3. That the computer is Grounding the relay's low current circuit (TEST 4). Put the voltage on for 12V to test the ground, and then go back to resistance. If the engine isn't turning, nothing happens. Ask an assistant to turn the ignition key to the start position — as if starting the engine — while you listen to the solenoid. The one at battery voltage will be Terminal 30. Compare this reading to the manufacturer’s specs. First, the relay has power and needs a ground to switch. May 17, 2021 · Locate the fuse box and locate the fuel pump relay. Symptom: The fuel pump keeps running even when the vehicle is switched off. When ready, ask your helper to crank the engine while you observe the fuel pressure tester's gauge. The next step is to verify that the fuel pump relay's high current circuit is being fed with battery power too. Oct 22, 2022 · As a result, in the event of a relay failure, the fuel pump will shut down, rendering it inoperable. Check the diagram of your fuel pump relay in your owner's manual if you can't find the fuel pump relay. Jun 20, 2016 · The fuel pump relay is a small plastic box that commonly has four wires connected to it. Mar 29, 2024 · 2. The multimeter tests for continuity by measuring ohms To prepare a multimeter for testing relays, follow these steps:1. Sep 10, 2011 · If nothing happens when you replace it, go to step 4. If necessary, the fuel pump relay can be replaced to restore proper fuel pump functionality . It requires only a small piece of wire, and you don’t need to touch the fuel pump. Locate your pump relay and take out the fuel pump. ”. when ign is turned on w/o start, not sure about VW. Turn on the ignition and check pin 87 with a multimeter. Swap the fuel pump relay with a similar relay from another Mar 4, 2024 · Quick Summary: 🔍 Step 1: Locate the Relay. Complete with diagram and illustrated functioning pictures. Use a multi-meter in diode-test mode to confirm your findings. If the pump works without the relay, then it's a real good bet that the relay is at fault. How to test fuel pump and fuel pump sending unit before installation or removal. TEST 5: Making Sure The Fuel Injectors Are Getting 12 Volts. Evey revolution of the motor the coil is grounded by the spark unit. Locate the fuel pump relay in the fuse box or power distribution center. I chose to use the RED for the 12v and the jump start terminal in the engine bay, the engine as the ground. We have looked through every relay and tested the connectors on the fuel pump with a multimeter. The automotive test light should light. The way that most folks determine if the relay works is if the pump works if you bridge the relay. In the ground wire, an OK fuel pump should read 12V. Put the new fuel pump relay into the socket that previously held the old one. Resistance of fuel pumps are usually 1-3 Ohms, Toyota 8 Ohms. So before you replace one, test the fuel pump using a fuel pressure testing kit. nd ls oi jq je if dx sg vg cn