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Discussion Starter #1
So this has been an off and on problem and needless to say, has been very annoying. A few months ago i started having no start and stalling issues from lack of fuel pressure. Its confirmed its a fuel problem. During no start issues the pump gets power at KOEoff but instead of making the normal priming noise, it makes a grinding sound, or a low fast rumbling sound. No fuel is pumped. Sort of sounds like a seized electric motor. I replaced the pump. It worked for a little while, but the problem came back. The code that is sometimes thrown is p1237. I know this code points to either a bad pump or bad wiring in the pump circuit. I replaced the wires and connectors going from the fpdm to the pump and it ran perfect for over a week. Then the problem came back. Exactly the same. Using this website to trouble shoot the fpdm
https://www.justanswer.com/ford/85te6-ford-2001-ford-focus-fuel-pump-not-working-12-vdc.html I found out its not a pump issue. It runs fine by jumpering the wires, or backprobing the pump ground signal wire at pin 3 and grounding it. After i back probe that wire and let the pump run at full power for a second, i can now prime and start it just fine normally. Until the problem comes back again.
On to the questions, does this mean its a spotty connection at the fpdm? Is the fpdm still a possible culprit? Is there anything else you all think i should check? Please any help would be amazing.
 

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First thing I would do would be to check the ground connection. Clean the ground and re-tighten, see if it doesn't improve.
 

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If by testing you are simply bypassing the fpdm then it has to be that, or connection to it.

Don't doubt what you see provided it is true.

If you replaced the pump ONLY and not the entire module, that is likely a mistake complicating things.
 

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Discussion Starter #4
Ok, so when i replaced the fuel pump, i also replaced the module, my fuel level sensor wires looked discolored in a spot on the in tank portion of the wires. Figured better safe than sorry. When i replaced the connectors and wires between the fpdm and the pump i also replaced the whole ground wire setup that leads from the pump and the fpdm to the bracket under the carpet. I also filed on the sheet metal and cleaned the bolt with a wire brush. All tests with the multimeter have shown good grounds. Now if i just backprobe the signal ground going to the pump from the fpdm at the fpdm connector, pin 3, the pump still makes the seized noise. When i apply ground to that backprobe with the key on, it runs the pump at full power. I turn off the key, I remove the backprobe, then i turn the key on to prime the pump, it primes normally. Well until ive been driving it, for say 10 minutes or even 2 weeks, then the problem comes back.
 

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Discussion Starter #5
Oh i should also mention after the second time the problem came back, i replaced the wires and connectors again using parts from another focus in the wrecking yard. So thats 2 fuel pumps, two sets of connectors and 2 sets of wires this problem has presisted on intermittently. The problem started out small originally, it would take a few cranks to start in the morning, or it would hesitate while driving. Then is progressed to stalling, but would restart usually on the first attempt. Then taking longer to restart, until one day it just didnt restart. Always with the same noise coming from the pump when trying to prime it.
 

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You have thrown all repeatability of being reliable out the window by so far using only possibly derelict pumps. If they use ethanol in your local fuel the pumps likely sat in it for a while to go bad.

Maybe not but now you cannot tell with any sureness of decision, what you are doing is tilting all your decision making toward worthless. While it may not be that, it just as easily could be 10 pumps doing the same as 2, the used parts have destroyed any applying of weed out or culling out techniques there. If the module was never opened up then 4 more connections (2 plug in) right inside it that could be bad too.

At the very least you better have pulled the modules apart to clean them out 100% or even worse, they can be completely full of crap BTDT. Any rust on low lying bottom section of pump itself says the impeller in the last 3/8" or so is corroded to drag, it may work at full speed but lower power has it begin to drag and worse as it heats up.

With a less than stellar pump it may run fine at full power but being able to with no drag at lower rpm is the mark of a good one. So now, you can't blame it 100% solidly on the good ground issue, or the fpdm. Ergo, extra fumbling around to accomplish nothing solid.

So, possible pump, FPDM, and now the pumps you have chosen yourself are an issue, the used angle, as possible problems there. While you will likely find a good one eventually at the yard, how long do you have to work on it? You work down the problems not add to them.

FWIW.............I LOVE scrapyard parts too, BUT.........fuel pump is one item I will NEVER get there, you guys continue doing it, I see way too much chasing of tail doing that and not the good kind.

Of course, yours, and do as you will...........
 

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Another thought.................I once had a battery go way down due to an alt bad, it did the same thing, the pump would drag and make noise. Did not know battery was low until the thought hit me and there it was.
 

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Discussion Starter #9
The replacement pump was a new in box delphi module. The other pump i mentioned was the original one i bought the car with. It was replaced because of the T.S.B.i assume because it was the new style pump. The only pick n pull parts are wires and connectors. Both pumps work when powered directly with battery voltage and ground.
 

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Discussion Starter #10
Also battery is at 12.43 volts at the battery and 12.38 at the fuel pump with the key on. Battery running is at 14.15 volts. The car runs at the moment, but wasnt this morning, until i back probed the connector at the fpdm for the modulated fuel pump ground. Then applied a ground to the chassis from the probe. After i primed the pump that way, the pump now primes and starts properly with the key with no current codes. My issue is thats not reliable and this is my get to work car.
 

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OK, you have weeded out a lot. If you are sure it's the connector then fix it. Not rocket science there.

Sorry I had to push you to get more specifics.

When it comes to wiring and connectors I commonly make my own, yard wiring due to what it is can always be a problem. Anytime you plug and unplug a connector more than twice you will likely have trouble with it unless you go back into it to tighten it back up, connectors are actually made to work only one time and even more so now with the multi-pin ones commonly used.

Still could be the driver module, they fail rarely but at some point somebody will get one that does. Pump grounds into it and it grounds to car frame. Module itself ramps speed up and down and dragging pump could easily be module off too.
 

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Discussion Starter #12
Hey no worries, i reread my post about pick n pull parts and realized it wasnt the clearest. Since the fpdm rarely fails, do you think that would be a ok part to grab from the yard today?
 

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Find one car that looks like doors or windows not open enough to get rain all over it and I would be willing to try that part from a yard.
 

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Discussion Starter #14
So problem came back. I found a amazing condition car that i can nearly swear never had its fuel pump touched donor. I took the wiring only off it and bought a new FPDM. The car ran amazing all day, until i went to leave from picking up my pizza. The same thing solved it and got me home. I jumped the fuel pump signal ground from the fpdm side of the harness to the chassis, and the pump will prime with the key properly again. Im figuring its either the pump, the wiring going to the fpdm or the pcm now.
 

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Discussion Starter #15
So just a rundown of everything up to date, but still having same intermittent issue ive been having for months now. So far the same issue has happened with the fuel pump that i bought the car with, a new drop in pump, and a new pump module assembly. The wireing has been replaced and checked 3 times. Ground wires running from fpdm and fuel pump to spot under the seat have been replaced, bolt and bracket cleaned and sanded.Tested for shorts, opens. Load tested, resistance tested. Fpdm has been replaced with a brand new motocraft unit. Inertia switch has been checked.
The pump always gets power, so i know the fuse and relay are good. When the problem happens while running, my car basically loses fuel pressure then dies. When i turn the key on to prime the pump, i get a quick dadadada noise instead of the priming noise for 2 seconds. No fuel is pumped at this time. Confirmed at the outlet hose of the fuel pump where it connects to the fuel filter. This problem goes away anywhere from a half a day to 2 weeks, then comes back. I can make the pump prime and run normally with the key only after i backprobe the ground wire running from fpdm to fuel pump at the fpdm connector, connect backprobe to chassis, turn on the key to prime. At that time the pump runs at full power. I turn off the key, remove jumper wire and backprobe. Then when i turn the key to prime again, the pump will prime and run normally until the fault returns. For the love of god im going to shoot my car if i cant figure this out. Any ideas? Basically the only things i havent replaced are the signal wires running between the fpdm and the pcm, and the pcm itself.
 

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Before I say next I must state that I do NOT know 100% how the fpdm works...........BUT.......it reads the speed of the pump to give the PCM a signal based on it. Then PCM alters the fpdm powering and grounding the pump to adjust speed in some way. If you are backprobing with fpdm still hooked up to the ground you are sending useless info to PCM as the backprobe drops all signal to PCM because the pure ground is easier for power to flow through, less then goes to fpdm. It may even damage the PCM. At the least the PCM may hold the useless info in memory to use that next time car gets started. Without knowing how low the input power is there it's impossible to tell if the backprobing through fpdm has damaged the PCM.

If the 'useless info' is low due to the pure ground to frame has sucked most of it up then PCM would get a lesser amount and think it was normal to adjust to that amount, thus making pump get too little power. The stutter. Maybe you should try to take a power read at pump power lead when it is stuttering like that.

Proof of nothing but it makes sense.

Sorry, I got nothing better than that. Thinking all the extra work has possibly messed something up, what multiple 'fixes' commonly do.
 

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Discussion Starter #17
Before I say next I must state that I do NOT know 100% how the fpdm works...........BUT.......it reads the speed of the pump to give the PCM a signal based on it. Then PCM alters the fpdm powering and grounding the pump to adjust speed in some way. If you are backprobing with fpdm still hooked up to the ground you are sending useless info to PCM as the backprobe drops all signal to PCM because the pure ground is easier for power to flow through, less then goes to fpdm. It may even damage the PCM. At the least the PCM may hold the useless info in memory to use that next time car gets started. Without knowing how low the input power is there it's impossible to tell if the backprobing through fpdm has damaged the PCM.

If the 'useless info' is low due to the pure ground to frame has sucked most of it up then PCM would get a lesser amount and think it was normal to adjust to that amount, thus making pump get too little power. The stutter. Maybe you should try to take a power read at pump power lead when it is stuttering like that.

Proof of nothing but it makes sense.

Sorry, I got nothing better than that. Thinking all the extra work has possibly messed something up, what multiple 'fixes' commonly do.
From what I understand, the fpdm works as a signal doubler. The pcm sends a duty cycle signal less than 50%, the fpdm sends the doubled signal to the pump. Then reports back to the pcm on the running condutions of the pump. Based on the reading from the fuel rail pressure sensor the pcm alters the signal to the fpdm to run the pump accordingly. Not the code my car throws, but this video explains how the fpdm works starting at 1:16 until about the 3 minute mark. https://youtu.be/GqZTkso6kSg
 

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Two things I would check next.
I would check the connector and wires leading to the fuel pump shut off switch in the passenger kick panel maybe I would even grab one from the junk yard and swap it incase the switch is faulty for some freaky reason.
The junk yard would probably only want $2-$5 for it, if they're anything like the yards around me.

Other suspects I would wonder about is the ignition assembly in the steering column, the evap module being plugged, or the FRPS being faulty and telling the ecu a wrong reading during startup.

Your issue and functioning work around makes me suspect that you aren't getting enough current, even though the voltage is fine.
I would of course scoop up a pump driver module from the junk yard and try it first,
if no change, then I would focus on the the shut off switch and the wiring leading to it and from it all the way to the driver module.
Another could be that you have too much gack in the tank and the sock is getting clogged up, but, surely you would have noticed that when you pulled them.

Make sure you use only 87, get it from a different source than usual if you always go to the same place.

And, I hope you changed the fuel filter before all of this madness, but, I'm sure you tried that first.
Good luck man. That's a strange one.

From what I understand, the fpdm works as a signal doubler. The pcm sends a duty cycle signal less than 50%, the fpdm sends the doubled signal to the pump. Then reports back to the pcm on the running condutions of the pump. Based on the reading from the fuel rail pressure sensor the pcm alters the signal to the fpdm to run the pump accordingly. Not the code my car throws, but this video explains how the fpdm works starting at 1:16 until about the 3 minute mark. https://youtu.be/GqZTkso6kSg
Sent from my SAMSUNG-SGH-I527 using Tapatalk
 

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Another thing I just thought of which, did hose me long ago: check the little rubber hoses that run into the module on the passenger firewall.
They barely reach the module, and, if your mounts are shot and letting the engine move around a lot, they could be unattached.

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