Just replaced my fuel pump but its not getting any power tested fuel pump relay and fuel fuse both good tested the wires all good.
Truck cranks but won't start been that way for 2 months. Replaced fuel pump but not getting any power. Tested fuel pump relay and fuel fuse both good. Tested wires on sending unit and coming from truck all are good. Fuel filter good. Even took fuel pump back to where I bought it they tested it and it worked. Not sure why I'm not getting power to my fuel pump. Also checked the inertia switch and it's pushed down all the way.
My car has 137140 miles.
My car has an automatic transmission.
Experienced mechanics share their insights in answering this question :
You need to look at the theft light on dash to make sure it comes on and goes off when you turn the key to the on position. If light comes on and stays on then your theft system is causing the fuel pump to not be engaged. I recommend you check the theft system and then scan the computer for theft system codes. You may need to reprogram the keys to work or you have an bad sensor for the ignition key in the steering column.
How to Identify and Fix Common car Problems ?
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If your car doesn`t start with a new fuel pump, chances are the fuel pump is either not hooked up right or is broken. Double check that the pump is correctly installed and all hose attachments are plugged in. Next, check for any blockages along the fuel line—this can also cause your car not to start.
Electrical issues: Electrical faults are also significant contributors to fuel pump failures. The most common electrical issues are rusted connectors, loose connectors, or melted wiring and connectors.
Another symptom of a faulty fuel pump relay is an engine that does not start. If the fuel pump relay fails the fuel pump will be left without power. The engine may still crank when the key is turned, however it will not be able to start due to lack of fuel.
The most common sign of a bad fuel pump relay is an engine that cranks but doesn`t start. A fuel pump relay will typically fail in the open position, preventing voltage from reaching the fuel pump. As a result, the engine will be starved of fuel and refuse to run.
The fuel pump shut-off switch has a red reset button on top of it.
If there is no power, the fault is in the relay again — probably the contacts are burned or stuck in the open position. Burned contacts can also fuse together, so that they stick in the closed position, so the component does not switch off. In either case, replace the relay.
The switch will usually come with a reset button that will reactivate the fuel pump if the switch was tripped. The fuel pump switch is an electrical component, and just the same as the rest on the vehicle, over time it can wear out and develop issues.
The electric fuel pump on a vehicle with a spark ignition engine is controlled by a fuel pump relay. The engine control module (ECM) activates the relay when operating conditions are correct. For safety purposes, the fuel pump relay is only activated when an engine speed signal is received by the ECM.
The relay bypass switch plugs in place of the fuel pump relay and provides direct control over the fuel pump circuit. Relay bypass allows the technician to control fuel pump independent of all on-board systems.
Fuel pump failures tend to be sudden and unpredictable, with few symptoms to warn the motorist that trouble is brewing. And the higher the mileage on the vehicle, the greater the risk of a fuel pump failure.
Relevant Questions and Answers :
the most relevant questions and answers related to your specific issue
Just replaced my fuel pump but its not getting any power tested fuel pump relay and fuel fuse both good tested the wires all good.
ANSWER : You need to look at the theft light on dash to make sure it comes on and goes off when you turn the key to the on position. If light comes on and stays on then your theft system is causing the fuel pump to not be engaged. I recommend you check the theft system and then scan the computer for theft system codes. You may need to reprogram the keys to work or you have an bad sensor for the ignition key in the steering column.
Not getting power to the fuel pump and the secondary air injection pump fuse keeps blowing
ANSWER : There are quite a few reports of PCM (Powertrain Control Module, AKA computer) failures causing your problem, but before you go replacing the PCM, do some more pinpoint tests. This may require you to find a wiring diagram of all the wires coming from the PCM.
The first thing I would do is to connect a scanner to the car and see if you can communicate with the PCM. As a technician, I have access to communities of technicians where repeat failures are reported. In these reports, it is most common when the PCM fails in this fashion, that you will not have PCM communication. If you do have communication and the Check Engine Light turns on with the key on, I would be leaning away from the PCM being the problem.
However, this is by no means conclusive. You could be correct in your thoughts about a wiring problem mid vehicle. On most GM vehicles, there is a connector along the frame rail for the wiring harness that services the fuel module in the tank. This has problems with corrosion because it sits under the vehicle exposed to the elements. But why am I doubtful of this, and this will require you to confirm where the power starts and stops, is you stated you didn’t have power from the fuse box. This would be before this connector and the fuel pump. If this is the case, I wouldn’t be thinking of a wiring problem mid vehicle anymore.
I am wondering if you confirmed the fuse box was getting power? It is a very common problem that when we move wiring we inadvertently move the damaged wiring and fix the problem for the short term. You may have done this when replacing the fuse box. Not to mention you seem to have an intermittent failure on your hands. This compounds the process quite a bit.
I’m not sure how you are confirming you have power at the various points, but I highly recommend a test light over a multi-meter. A test light draws current and a multi-meter does not. There can be voltage present but not a good enough connection to carry current. This is a very important distinction when you are battling bad connections. The problem with a test light though, is knowing when it shouldn’t be used. Some test lights draw too much current and can damage computer modules. Even us technicians perform tests on modules at our own risk.
The best way to test a relay is to simply use a jumper wire to bypass them. If I suspect there is a problem with the power supply to the fuel pump, this is the first thing I do. This way I can be sure it isn’t the relay or the PCM that turns the relay on. If the fuel pump does not run, use the before mentioned test light to find where the power stops. This requires you to methodically track the wire back to the fuel pump. I usually start at the central connector, if it has one. Not all of them do. I go directly to the pump if I can, but this is often not easy to access without dropping the fuel tank down. If you successfully confirm power to the pump, it maybe a bad ground, in which case the easiest way to confirm this is to add a ground yourself.
If this circuit checks out good, a few other things to check are power and ground to the PCM. Locate the wire from the PCM that powers the fuel pump relay. This can be done at the relay connector while you are testing the fuel pump circuit without the relay. When you turn the key on, on of the four terminals should receive power from the PCM for a few seconds. It will turn off after a couple of seconds if the PCM doesn’t see a signal that the motor is running. This is normal operation.
As for the air pump, I wouldn’t think this is an indication of the problem unless this occurred at the exact same time as the fuel pump failure. If so, I would suspect a wiring harness is shorting to ground somewhere. If they didn’t occur at the same time, this is most likely a separate issue.
The challenge you have here is isolating each part of the system. The PCM, the fuel pump relay, or a wiring issue. The PCM is actually fairly easy to check. Is the Check Engine Light on with key on and does it communicate with a scanner? Then follow the fuel pump relay test I outlined above. If it is a bad connection somewhere in the system, you will need a good wiring diagram and a well thought out plan to isolate where the problem is. This can be the most difficult to diagnose, especially if the problem is intermittent. Find a wiring diagram and study it carefully. If you’d like help, you can have a qualified technician, such as one from YourMechanic, to inspect your car’s loss of power and make the correct repairs.
Good luck. I hope I have been of assistance.
Car will crank but no start… Fuel pump not coming on. New pump, relay, etc. Will start when hot wire runs from pump wires to bat
ANSWER : There are a couple of approaches to take here – either start from the battery and work "towards" the fuel pump, fuse box, ignition switch, fuel pump relay, and wiring connections in between. Or, as you have done, start at the pump with 12v, and move backwards towards the battery. This will require a GM service manual, or wiring diagram at least, with connection locations as well.
I would recommend having a certified technician from YourMechanic diagnose this starting issue, get an accurate assessment of damage and cost estimate for repairs. YourMechanic.com can dispatch a mobile, professional mechanic to your location for this repair.
Car is not getting fuel. I changed fuel pump and checked the fuel pump relay. It was in good condition. What else could it be?
ANSWER : This may likely be related to the fuel pressure regulator. This is a unit that helps to maintain the fuel pressure in the system. When this is not working, this may cause an erratic fluctuation in the fuel pressure or in some cases, no fuel pressure at all. If you’d like assistance with this repair, I would recommend having an expert from YourMechanic come to your location to diagnose the issue firsthand and service your fuel pressure regulator as necessary.
I put a fuel pump in and a fuel pump relay. The relay works but there is no power to the fuel pump.
ANSWER : Hi there. There could be an issue with the wiring to the fuel pump between the fuel pump relay and the fuel pump. Remove the wiring to the fuel pump and check the resistance from the wiring from the relay to the fuel pump. There should be no more than 1 ohm of resistance. If there is more resistance than 1 ohm, then there is a break or corrosion in the wiring. Also, check the ground circuit and make sure that the fuel pump is getting a proper ground. If you need further assistance with your fuel pump not operating, then seek out a professional, such as one from Your Mechanic, to help you.
I changed the fuel pump in my car thinking that it was the problem, but I’m still not getting power to my fuel pump.
ANSWER : If there is access to a wiring diagram, you can disconnect the fuel pump harness and install a test light in between the power and ground circuits and turn the key to accessory or try to start the vehicle and if the test lamp lights up, the circuit is not the problem and you may have picked up a faulted new fuel pump. IF you can hear the fuel pump power up and there is no fuel pressure at the fuel rail, the fuel filter may be clogged. Consider hiring an experienced technician like one from YourMechanic who can come out for a closer inspection of the vehicle to run a few tests and offer a more personal diagnosis of your fuel system concerns.
No power to the fuel pump
ANSWER : Hi. I would go back over a few things. Specifically, the fuel pump relay and fuses. Check the voltage drop across the fuel pump relay while trying to start it. An older relay will pass a resistance test (the contacts do indeed touch) but won’t pass enough current because the contacts are burned.
Also check the fuses for the ECM as well. Check the oil pump pressure switch – this is a low oil pressure fail-safe to protect the engine. Last but not least, make sure the ground for the fuel pump itself is good and clean. When you removed the bed, you removed several ground wires for taillights, and the fuel pump. Make sure it’s back on with a good clean ground. If these checks are not successful, I would recommend having an expert, like one from YourMechanic, inspect the loss of power and address this issue properly.
Crank, No Start, replaced fuel and relay.
ANSWER : When you applied power to test the pump directly, you may have had the power and ground backwards, and ran the pump backwards.
The pump connector that is only getting 8 volts should be replaced. The connectors are known to have a problem with voltage loss through the connectors due to corrosion. Replace the connector and it should fix your problem. Do not insert your big tester pin into the new connector or you may damage the female connector.
