Tip & How-To about Miscellaneous

Fuel pump not running

Run a wire from the power side of your fuel pump to the battery have an assistant momentarily touch the wire to the battery and listen for the fuel pump motor to run it sounds like a 4 second buzz;
if you hear nothing your ignition switch is bad if you hear the motor
clean the ground wire to frame connection to the fuel pump.

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engine won't fire

There are a lot of potential causes for your problem. The pattern is similar to a fuel pump failure I had in a 1992 Buick, but before embarking on a fuel pump replacement, there are a few tests you can do.

Check fuel pump operation: Open the fuel filler cap and listen to it while an assistant turns the key to the "On" position. If the fuel pump is working you should hear it running clearly by listening to the top of the fuel filler tube. The reason you need an assistant to turn on the key is that if it's working correctly, your fuel pump will only run for a few seconds.

Check ignition system (only applicable to gasoline engine): Remove one spark plug (doesn't matter which) and connect the plug wire to it. Place the plug in a secure location on the engine touching something metal and away from explosive vapors (that can come from the battery or blow out the now open spark-plug hole) Stand back where you can see the plug clearly and ask your assistant to crank the engine (turn the key to "start") If the ignition system is working properly you should see sparks jump between the contacts on the spark plug. This test is best performed in low light so the sparks are more easily seen.

Mar 18, 2014 | 1992 Mitsubishi Pajero

1 Answer

replaceing fuel pump

How to Replace a Fuel Pump
DIY & Save up to $219.24 (Complexity: Hard / Time: 3.2 hours)

1. Fuel Pump - $140.07

1. 3/8 in. Drive Ratchet - $7.55
2. Floor Jack - $145.54
3. Multimeter - $247.13
4. Jack Stand Set - $36.93
5. Flat Head Screwdriver - $3.14
6. Mallet Hammer - $6.83
7. Socket Set

1 Locate the fuel pump.
- Tip: Safety Tip:Always wear safety glasses when working on your vehicle. Wear other personal protective equipment (PPE) when necessary, for example latex gloves or safety shoes.
2 Have a friend turn the key to the“ON” position while you listen for a high pitched hiss/whine coming from the electric fuel pump.
- Tip: If the fuel pump is located in the fuel tank, you can open the fuel cap and listen to hear the fuel pump. The fuel pump should run (priming the system with fuel) for a couple of seconds. Once it stops, you should be able to start the vehicle.
3 If the fuel pump does not make a sound (run and prime the fuel system) check to see if there is a fuse that supplies power to the fuel pump and check its location.
- Tip: Check the owner’s manual for location of the fuse box and fuel pump fuse.

4 Once you have found the location of the fuel pump fuse, remove the fuse from its housing and check to see if it is blown.
- Tip: A blown fuse will usually have a metal strip connecting both tabs that“blows out” (the wire looks as if it has been chopped in half or broken).

5 If you noticed that the fuse was blown, replace the fuse with a new fuse of the same amperage and repeat step 2.
6 If the fuel pump now works, you do not need to replace it. However, you will need to find what caused the fuel pump fuse to blow. We strongly recommend that this is done through a certified shop, unless you have the tools and knowledge to test electrical systems and diagnose more in depth problems.
7 If the fuse wasn’t blown, it should be checked for power and ground at the fuel pump. If there is power and ground present then you will need to replace the fuel pump.
- Tip: On most vehicles you may need to lower the fuel tank to access the power and ground leads for the fuel pump.

8 Siphon or drain as much fuel as possible from the fuel tank. Disconnect any possible fuel lines from the fuel tank.
9 Remove any retaining straps or bolts holding the fuel tank to the frame.
- Tip: You may be able to access the fuel pump from the bottom of the back seat or the trunk of the vehicle.

10 Using a digital multi meter, turn the key to the“ON” position and check for power at the fuel pump. Touch the negative lead from the DMM to a good ground and the positive lead of the DMM to the power cable at the fuel pump. You should have a reading that is equal to battery power. If you do not have a reading at all, you will need to inspect the power side of the fuel pump.
- Tip: With the ground lead of the DMM still connected to a good ground, touch the power lead to the positive side of the battery, to each side of the fuse, and again to the fuel pump. Wherever you notice the voltage reading goes from battery voltage to 0 you will need to replace whatever wires and fuse are in between.

11 If you have noticed that the power and ground being supplied to the fuel pump are both good, then you will need to replace the fuel pump.
- Tip: To check for a good ground, place the negative lead from the DMM to the ground side of the fuel pump, and the positive lead of the DMM to the positive side of the battery. If the reading on the DMM is battery voltage then you have a good ground.

12 Remove any retaining rings or bolts that hold the fuel pump in the fuel tank.
13 Remove any electrical connections or fuel lines connected to the fuel pump. Replace the fuel pump.
- Tip: If equipped, inspect and replace strainer as needed.

14 Use reverse procedure to install fuel pump and assemble all components back to their original state.
15 Start the vehicle to verify repairs.

Hope helps with this (remember rated this help) Good luck.

Feb 09, 2010 | 2001 Chevrolet Silverado 1500

2 Answers

no power to the fuel pump

Once you check the fuel inertia switch in the passenger's side kick panel, next is to check the fuel pump fuse, engine compartment fuse # 10.

If this checks OK ( power on both sides ), you can pull the fuel pump relay, and jumper it.

The engine compartment fuse panel is where the fuel pump relay is located at ( relay # 301 ). Pull the fuse pump relay out of the socket, and using the diagram below, with the red line, momentarily jumper the Normally open contacts, you shoud hear the fuel pump run. ( mind the pin orientation when doing this ) :

I had a bad fuel pump relay on my 2001 F-150 @ ~ 36K miles. Replaced with the trailer tow battery charge relay ( relay #302 next to it ) and it worked again.
The symptom I had was a crank no start ( theft light on dash went out ).

If the fuel pump does not run, and power is on pin #30 in the relay socket, next is to check the output of the fuel inertia switch in the passenger side kick panel. The output of this is the Pink w/ Black stripe wire. The connector to the fuel pump inertia switch should be a 2 pin connector, the other color in the connector is Dark green w/ Yellow stripe wire ( that is from the pin #87 in the relay socket in the engine compartment ).

If that circuit has power at the passenger side kick panel, next is to check for power at the fuel pump at the fuel tank. The fuel pump motor is the same Pink w/ Black stripe wire. The connector is a 4 pin connector with black ( ground for the fuel pump ) black w/ orange stripe ( ground for the fuel level ) and yellow w/ white stripe ( to the instrument cluster for the fuel gauge ).
When testing by the fuel tank, make sure you have a good ground for the meter ( extension from neg on the battery or trailer tow adapter ) as that could also be a problem under the truck.

Sorry for war and peace, hope it helps.

Nov 17, 2009 | 2001 Ford F150 Styleside SuperCrew

1 Answer

No Power to Fuel pump

I would check the ground for the fuel pump relay that operates the switch side of the relay.
You should have 2 12v inputs to the relay. When the relay gets 12v input, it closes the relay switch on the heavy current side that sends 12v to the fuel pump.

A relay is needed because you don't want heavy current going through the switch.

Also, most cars only run the fuel pump for 2 seconds when the key is turned on because you don't want the fuel pump running without the car running. If you listen closely at the fuel tank, you should hear the pump run for 2 seconds when you turn the key to "ON"
When the key is turned to "START", the fuel pump should run continuously.
The engine computer tells the fuel pump to shut off if the engine rpms are zero.
So, I would check the switch side of the relay. Power amd ground.

Mar 01, 2009 | 1992 Jaguar XJ6

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