UHG!! Fuel Pump issues

[Mrs.Burley]

Can't get my Explorer to start the fuel pump will not kick on and it was replaced a year and a half ago thought it might be the cut off switch checked it and changed it still nothing. Dont know what else to do please help me!! I need this to start to get to work missed one day over this and i cant miss another!

 

[Snowboi]

You sure its the fuel pump? Have you checked both the fuse and the ground for the pump? What about the filter?

 

[ld50]

You should be able to narrow it down by first seeing if it is delivering power to the pump. Unhook the power connection at the pump and check it with a multimeter, It might be the same wiring as the post below.

If you turn the ignition on and there is no power there then something is wrong with the power distribution. If there is power there then it is your pump, you can also test the pump by connecting 12 volts to the connection.

-But don't blow yourself up.


http://www.explorerforum.com/forums/showthread.php?t=165653&highlight=fuel+pump

 

[Pontisteve]

The ignition switch sends a "key on" power signal to the PCM. Once the PCM knows you turned your key on, it sends a priming pulse to the fuel pump. While starting the engine, the fuel pump probably runs as well. Finally, if the RPM exceeds a couple hundred RPM, the PCM knows the motor is running and continues to power the fuel pump.

So basically, the PCM sends a low power signal to the fuel pump fuse, which sends power to the fuel pump relay. The relay then sends bigger power to the pump. Quick checks are as stated above, is power getting to the pump when you first hit the key (it will prime for a couple seconds). Check the fuse and the relay first. Make sure the fuel pump crash safety cutoff switch is reset.

If no power to the pump, is the signal getting to the relay? If no power to the relay, is the signal getting to and thru the fuse? If all else fails, check the wiring and then the PCM output directly at the connector.

9 times out of 10 it will be the fuse or relay is bad. You can either jump the relay to test, or swap it out with another relay of the same part number temporarily.

 

[budwich]

for a "quick fix", run a "temporary jumper" from a battery source (ie voltage) that is "active" with "switch on" to "just past" cutoff switch. The pump should run "forever" when your switch is "on" and your truck should start IF the pump has some form of "electrical problem". However, rather than just "fooling around", get a meter and check things out on the circuitry and the pump itself looking at the voltages (and grounds) in the circuit and resistance of the pump. You will likely get a quicker idea of what your problem is.

 

[Mrs.Burley]

How do you check if the relay is bad?

 

[Mrs.Burley]

Ok so I went outside and it started I dont know what happened. but I still want to know what it would cause it to do that I didnt drive it to work for fear of getting stuck somewhere. So any ideas?

 

[Pontisteve]

You could check the fuel pump fuse for corrosion or a loose connection. Removing and installing the fuel pump fuse a few times usually guarantees that connection is good. So does a new fuse.

But more likely is a fuel pump relay. Over time, contacts in relays wear, and can get inconsistent towards the end of their life. They're not a whole lot of money, and they're very easy to install. If you're worried about intermittent breaking down, maybe buying one as a guess isn't a bad idea.

If it were me, I would probably wait and see if the problem ever returns again. If you check out how a SPDT relay works on the internet, you'll see how to temporarily jump one. If you really wanted to, you could make up a jumper wire that is about 12 gauge wire, 3 - 4" long, and has a male spade connector on each end. Keep that jumper with you, and if you ever have a relay go bad, you could easily temporarily jump the relay by installing this cheap jumper.

For that matter, if you got caught on the side of the road, you could just steal a relay from something else, and temporarily install it as a fuel pump relay to get you home. Im sure there are other identical relays under the hood. Maybe one for Air Conditioning, or some other non-essential component.

Whatever you do, you should at least figure out exactly where your fuel pump relay and fuel pump fuse are, so you know. And once you find them, at least unplug them and plug them back in to make sure they have a good connection.