Car Cranks But Won't Start "No Fuel Pump Sound"

Car Cranks But Won't Start

If you find yourself in this situation, often times it can be a simple fix. The first thing you want to do is listen for the fuel pump when you turn the key to the on position. The fuel pump should make a humming noise when it is priming. If you do not hear this sound, then this most likely is your problem. Continue to follow this "Car Cranks But Won't Start No Fuel Pump Sound Guide" to troubleshoot your issue.

Checking The Fuse Box First

The first thing you are going to want to do is check the fuse box. It's very simple, it's located underneath the engine bay Hood. With this example the fuse box is positioned by the battery on the passenger side and it is a 7.5 amp fuse. Check this guide to verify if you have a good fuse or a bad fuse.

Now for most vehicles the main relay varies in it's location. The majority of the main relays are located underneath the driver side dash towards the left, and also behind the passenger side glove box to the right. This particular vehicle which happens to be a 1998 Honda Civic coupe, the main relay is located behind the glove box to the right. Honda civics 92-95 are located underneath the driver side dash to the left. Honda Civic's 96-00 are located on the passenger side behind the glove box to the right.

Locating The Main Relay

Removing The Main Relay

Pulling the main relay is simple in this scenario. You simply press in on the glove box sides firmly and then pull the glove box towards you. This will allow the rubber bumpers to move past the stopping frame. Now that you have access, look to the right and you should see your main relay. The next step you will need to open the passenger side door and get access to the side panel, remove the phillips screw and pull firmly to pop the clips off the side panel. Now you can see that there is a 10mm bolt, remove the bolt and pull the main relay off the dash frame. Next push on the electrical clip to remove the plug from the main relay.

Repairing The Main Relay

To repair the main relay you need to remove the casing over it. Simply put a flat head screwdriver over either side and push out as you pull up. The internals of the main relay will slide out. What you will need for this job is a soldering kit and some flux flux. You can remove the white plastic plug clip from the relay so it won't overheat and melt. Next you're going to add some flux to the back solder joints. You can see in this image how the solder joint is cracked. This is what you will be looking for. Once you've added the flux you can take your soldering iron once it's up to temperature, hold it on the joint, and then add in some solder to repair each solder joint. When you're finished, clean it off with rubbing alcohol and a toothbrush and dry it off. Next place the main relay internals back in the casing and slip over the white plastic connector clip and push firmly until the black casing clips back in.

When solder joints get cold they contract and causes a short which disconnects the voltage. When the main relay heats up, the solder joints expand making contact again and your fuel pump will start working again. That is why this is an intermittent problem with some days the fuel pump working and others it will not. In some cases you cannot repair the main relay because the relays themselves go bad along with the resistors.

What Happens When A Solder Joint Cracks?

Installing The Main Relay

Now that you've repaired the solder joints on the main relay you can install it the same exact way you removed it. Plug the clip back into the main relay put the main relay back up to the frame, put the 10 mm both back in and tighten it down. Then you'll just add your panel back on, then push on the sides of the glove box to push the glove box back in.

When ECU capacitors go bad this can affect the voltages which effects the way the ECU communicates with other components it's linked to. It's very common when capacitors inside the ECU/ECM go bad that this will cause fuel pump priming issues. Some days the fuel pump will prime, and other days it will take 5-10 minutes for the fuel pump to prime. These are Tell-Tale signs of possibly bad capacitors inside the electronic control module or electronic control unit.

Bad ECU That's Not Priming The Fuel Pump

Repairing Bad Capacitors In A Electronic Control Unit

The repair is quite simple. Simply locate your ECU/ECM, unplug the wiring harness. Next unbolt the casing from the control unit. Once you're able to access the motherboard you will be able to locate the capacitors. Make sure you replace all of them. Never change the (μF) amount when replacing the capacitor. It's completely fine to increase the voltage on the capacitor, but never change the (microfarad...aka: μF). Example: 47μF 10v... "Replacement" 47μF 25v is (OK). Pay attention to the white line with a negative emblem on it, that's the negative side and the other side is the positive. Do not place the capacitor in the wrong position. Make sure you add some flux to the backside of the solder joint as you heat and pull up on the capacitor. Just follow the simple soldering steps as seen with re-soldering the main relay above. Once you've soldered in the capacitors, all that's left is to reinstall it and test it out. The ECU demonstrated is a OBD1 p28 out of a 1992-1995 Honda Civic.

* The Capacitor kit in the store below has every CAPACITOR REQUIRED for this repair. NOTE: Other kits are missing some of the capacitors needed to complete the repair.

What If I Replaced Everything In This Guide And My Vehicle Is Still Not Getting Fuel?

If you followed all the steps in this guide and your fuel pump is still not priming by making a humming noise when you turn the ignition on, then you will need to replace your fuel pump. For most Trucks the fuel pump is underneath the bed of the truck. Watch my Ford Ranger fuel pump replacement video for the repair. For most Honda's fuel pump is underneath the rear seats. Other vehicles you will have to drop the fuel tank to gain access to the fuel pump.

What If My Car Wont Start As In Turn Over?

If your car wont crank, or when it cranks, it seem like it doesn't have enough power, you may have a dead battery. If your car wont start with a jump, and you find your car completely dead, then it's time you buy a new battery for your car.