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I have 2004 ford Escape 3.0. At 62K the fuel pump went out, just stopped pumping. I replaced it with a Motorcraft pump and all was well for 2 months, then that pump quit, so I replaced it again. Now it’s 2 months later and the 3rd pump has quit. The question is, is this just a bad coincidence or is there another reason for all these failures that I should be looking for? My fuses, relays and wiring seem to be ok and the car has been babied since new, including being garaged and never off road. Any help would be appreciated, thanks.
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What is the name and model of that alarm? (That alarm isn’t doing a better job than the factory system does) I posted a diagram above.
Thanks much to jacobnbr1 for the wiring diagram, that makes things a little easier. If I’m reading it right, I am on the right wires with the black and pink black. So I think my 6.65 volt reading is correct. I was originally thinking that voltage could be variable through the PCM. I need to do the drop test and other tests jacobnbr1 suggested and see what I come up with. Answering some of the back posts, I have 12.5 volts on the battery and have switched relays to known good ones. Thanks for sticking with me guys!
No I already checked for remote mounted driver, that car don’t have that system.
Yes you are reading it right pnk/blk and blk.
Look at that diagram and look at all the voltage stops along the way and where ever there is a component there is a potential for a voltage drop starting at the fuse box feed to the fuse.
It only requires battery source voltage from the output of the fuse so if you confirm the 6.65 volts at the pump, change over to the ground wire side and run the test lead from battery positive to the fuel pump ground and if it reads 12.4 (or whatever source voltage is) then the ground is perfect but the problem is in the positive side circuit of the vehicle harness.
You can move on from there and test the voltage drop at the output of the inertia switch, relay, fuse and if you have 6.65 there, then the problem is in between that component and the pump connector.
Let me know if you don’t understand and I will break it down for you.
I mean lets make an example…
The battery for the available source for what it is of say 12.5 with the fuel pump energized (fuel pump prime, key on engine off) so we leave the battery with 12.5 and go to fuse f16 utilizing a protection of 20 amps(and still having 12.5) following that wire to the fuel pump relay and exiting (still having 12.5) then on to the s138 splice(still having 12.5) then passing through the crash safety feature inertia switch exiting with (6.65) and continuing to the pump connector (with only 6.65). In this example the inertia switch is causing the voltage drop because we should transfer the full 12.5 to the pump with the pump energized(fuel pump prime, key on engine off) but can’t because say the windshield leaks water into the cabin and down the A piller into the switch causing corrosion and a bad connection. (true story on an f series truck)
Yes I know. We mechanics have become spoiled with bi-directional testers that can command the pump on.
You need to try and get a voltage test on the neg side and if it is ok then we know the circuits are good.
It’s not as easy as many people think is it?
No it’s not easy at all, I’m pretty much lost now. I can’t get a reading on the negative side and I’m reading battery voltage on the positive side with the key off and nothing legible with the key on. I think it’s time to take it into the shop. Thanks for all your efforts, it is appreciated!
It takes a basic set of experience to talk in automotive terms specially in todays modern vehicles with many high tech scopes, meters, and scan tools.
The profession is being revolutionized, Brute force has been supplanted by brain power and this is rocket science.
I figured I could help out with trouble trees, wiring diagrams and technical service bulletins but after reading alot of what I’ve posted to help others I keep hearing that inner thought ‘ How do you expect this person to perform this type diagnostics with a multi meter and small knowledge’ and the answer is I can’t.Anyway, let me know what was wrong with it when you get it fixed.
Ok, here’s the latest update. I was wrong on the 6.65 voltage figure, that was mV after prime. The voltage on the pump just flashes for a second, it is 11.90 volts and within .5V of battery voltage. The positive side on the drop test is also 11.90 volts. I can’t get a reading on the negative side and I don’t know why? This is with the pump working again so I can hear it prime but i can’t get a reading.
Can you read battery voltage on the positive side of fuel pump motor or just the connector to the pump motor? The pump motor should spin on proper connection to battery and ground, plain and simple, no rocket science. Any connector without a connection to its load can read battery voltage as long as it is connected to battery. Make the connection to the motor and you will see what the motor gets for voltage. Put a current meter in series with the motor connection and now you can get the current reading and calculate for power. As long as battery voltage is sustained at the pump motor, and properly grounded, I see no problem there.
There has been no mention of the pump prime cycle time (3 seconds?) or the acquisition speed of your meter.
From the schematic, I see that the PCM controls the pump relay, and also has a voltage sense on pin 40. This voltage sense tells the PCM that the relay contactor has closed, nothing more. What we don’t know is, how does the PCM respond if it does not pick up the battery voltage after the relay is energized? We also don’t know what sense voltage range is considered acceptable by the PCM before it would generate an error.
With one end of your meter connected to battery ground (get a long #12AWG stranded wire with alligator clips soldered on each end), you should be able to poke the other end of your meter on all parts of your circuit to find where battery is and battery is not. Don’t use key ignition as part of your diagnostic, unless the only problem your are having is the pump motor prime cycle. With that, you would need someone to turn the key while you are taking readings at the pump relay and the PCM voltage sense pin.
Your car should have electronics that can protect itself. In other words, faulty wiring to the PCM wont destroy the PCM, but it will shut itself down to protect itself.
I also question the alarm system. It’s not included in the schematic, so you don’t know how it’s connected to your fuel pump circuit.
Last mention, there is nothing in your circuit that would destroy the motor. Two months runtime tells me that it’s either debris from the tank or poor quality. Oh, unless your pump is running 24/7 from faulty wiring. That would suck.
HTH,
Jeff
Quoted From escape1:
No it’s not easy at all, I’m pretty much lost now. I can’t get a reading on the negative side and I’m reading battery voltage on the positive side with the key off and nothing legible with the key on. I think it’s time to take it into the shop. Thanks for all your efforts, it is appreciated!
escape1,
try this- measure continuity (or resistance) in ohms between the negative terminal of your battery and the negative terminal of your fuel pump. According to the schematic it should be fractions of an ohm.
By your results I am suspecting an open ground since you can’t get a reading on the negative side. We should at least rule this out anyways.
Do not do this test on the positive side…
Maybe this will help.
The load MUST be on to do a valid voltage drop test!!!
Since I am working alone, I made up a jumper wire and jumped the relay and tried to do the drop test again. With the battery at 12.55 volts and the pump running I connected the DVOM from battery negative to pump positive and read 11.64 volts. From battery negative to pump negative no voltage. From battery positive to pump negative was 12.23 volts and from battery positive to to pump positive I got .71 volts. I also tried what Twiggy suggested and had no measured resistance between the battery negative and pump negative there was continuity.
Those voltages are not trivial, there is a valid voltage drop issue and should be corrected.
The .71 is too high on the pos side.
Although you didn’t get a valid drop test done on the negative lead I see a problem in the voltage alone and there is about 1.0 volt loss there too.There is two theifs in the circuits causing a 2 volt drop in the fuel pump circuits,The pump is designed to run at min of 12 volts and is being run at times at 10 volts but probably much worse when the load has been working for a while building heat in the circuits.
Starving the pump for voltage can cause erratic behavior and lead to premature failure. (And I don’t care what anyone else has to say about it)
Quoted From jacobnbr1:
It takes a basic set of experience to talk in automotive terms specially in todays modern vehicles with many high tech scopes, meters, and scan tools.
The profession is being revolutionized, Brute force has been supplanted by brain power and this is rocket science.
I figured I could help out with trouble trees, wiring diagrams and technical service bulletins but after reading alot of what I’ve posted to help others I keep hearing that inner thought ‘ How do you expect this person to perform this type diagnostics with a multi meter and small knowledge’ and the answer is I can’t.Anyway, let me know what was wrong with it when you get it fixed.
I struggle with this often and my best answer is ‘video’.
It does sound like an excessive voltage drop, find that but checking the voltage drop at different points along the circuit that you can find esepcially at the connectors, there should be NO voltage drop across a connector, if you find one then check for corrosion or a bad connection. So many electrical issues come down to faulty connections.
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