The Autonerdz Community Forums - First time user, fuel pump waveform.

Dr. Jake Super Nerd Picogroup Offline Deceased Posts: 734 Laurens SC (Jerkwater) South Carolina USA Gender:	Re: First time user, fuel pump waveform. Reply #15 - Dec 22^nd, 2010 at 7:12am A new pump wouldn't look like that.
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Davidlee

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Re: First time user, fuel pump waveform.
Reply #16 - Dec 22^nd, 2010 at 10:21am

Andy_ wrote on Dec 21^st, 2010 at 8:35pm:

Spence, the customer's concern was it died out in a parking lot. It cranked but would not start. Once I got it in the shop it started. I scanned it and had P0231-fuel pump secondary low. Most of the time it runs fine, but I have had a few times where it will start for a few seconds, then the fuel pressure drops of and it dies, also a few times it blew the fuel pump fuse, so I figured this would be a good time time try to scope a fuel pump. I wasn't so worried about the speed, but on the sample waveform, the current peaks are much more even, what do you think of the one that I posted, thanks for your help.

All of the symptoms you described are typical ford fuel pump failure symptoms, although I am unable to see the fuel pump initial ramp the amp draw is high and so is RPM, and the comutators do not look good at all. I would never condem a fuel pump based on a bad waveform, but if the symptoms pointed me in a fuel pump direction and I saw that waveform I would be putting in a fuel pump.

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Mick LSD Guide Offline I learn every day Posts: 7,471 Toronto 400ft Ontario Canada Gender:	Re: First time user, fuel pump waveform. Reply #17 - Dec 22^nd, 2010 at 11:10am Andy_ wrote on Dec 21^st, 2010 at 8:47pm: Mick, the 5 second file is 407 KB Then you can post it here please do that Mick
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jarvissamuel

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Re: First time user, fuel pump waveform.
Reply #18 - Dec 22^nd, 2010 at 11:44am

Schumi,

There is something wrong in the image posted of the fuel pump the current should start high since it is not moving and then the current should drop to a stabilized pattern once the pump is moving.

Each vehicle is a little bit different on what a normal amperage reading is. Some like to use 1 amp per 10 psi. I can not say with authority on the FP posted, to me the current seems high.

If you can post the psd file or at least zoom in on the turn on and post it that would be awesome.

Here is an example of a typical fuel pump turn on:

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2000_F150_54L_FP_current_test_INV_19887.psdata (1062 KB | )

2000_F150_54L_FP_Current.gif (34 KB | )

2000_F150_54L_FP_Current_zoom.gif (48 KB | )

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Andy_ Super Nerd Picogroup Offline Posts: 1,398 DeMotte, IN Indiana USA Gender:	Re: First time user, fuel pump waveform. Reply #19 - Dec 22^nd, 2010 at 12:22pm Thanks for the replies. I will post the whole file when I get off work.
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Andy_ Super Nerd Picogroup Offline Posts: 1,398 DeMotte, IN Indiana USA Gender:	Re: First time user, fuel pump waveform. Reply #20 - Dec 22^nd, 2010 at 6:27pm Here is the 5 second file.
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Mick LSD Guide Offline I learn every day Posts: 7,471 Toronto 400ft Ontario Canada Gender:	Re: First time user, fuel pump waveform. Reply #21 - Dec 22^nd, 2010 at 7:57pm Schumi It is most unusual to see the pump speed up and Amps increase. There is a 2000 RPM difference, so I would have to say that this pump would have worn/tight bearings and the pump chamber must be leaking fuel back into the tank. Fuel volume must be low. Mick
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Andy_ Super Nerd Picogroup Offline Posts: 1,398 DeMotte, IN Indiana USA Gender:	Re: First time user, fuel pump waveform. Reply #22 - Dec 22^nd, 2010 at 8:39pm I changed the pump and the filter. The filter was quite plugged. Also, I took apart the pump and the magnet was cracked into a few pieces. I will post the waveform from after it was changed because I still have a few questions.
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Rick Hill

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Re: First time user, fuel pump waveform.
Reply #23 - Dec 23^rd, 2010 at 10:38am

Quote:

It is most unusual to see the pump speed up and Amps increase.
There is a 2000 RPM difference, so I would have to say that this pump would have worn/tight bearings and the pump chamber must be leaking fuel back into the tank.
Fuel volume must be low.

Mick Wouldn't low voltage create low speed and low current flow
Usually when I see low current and low speed I suspect a voltage drop problem either the circuit or the pump itself. This one may have been on the verge of getting it started by slapping the bottom of the tank

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Rick Hill

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Mick

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Re: First time user, fuel pump waveform.
Reply #24 - Dec 23^rd, 2010 at 12:36pm

Rick Hill wrote on Dec 23^rd, 2010 at 10:38am:

Quote:

It is most unusual to see the pump speed up and Amps increase.
There is a 2000 RPM difference, so I would have to say that this pump would have worn/tight bearings and the pump chamber must be leaking fuel back into the tank.
Fuel volume must be low.

Mick Wouldn't low voltage create low speed and low current flow
Usually when I see low current and low speed I suspect a voltage drop problem either the circuit or the pump itself. This one may have been on the verge of getting it started by slapping the bottom of the tank

Rick

Fords usually run at 5 amps and a speed of 6000 rpm so his start up is some what normal even though its not.

I have never seen one that increases in speed and amps that was good.

It would have been right if we had instructed Suhumi to hook up to voltage and grouind at the pump before he had replaced it.

Mick

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Mick

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Andy_ Super Nerd Picogroup Offline Posts: 1,398 DeMotte, IN Indiana USA Gender:	Re: First time user, fuel pump waveform. Reply #25 - Dec 23^rd, 2010 at 1:57pm Here is the pump after being replaced. Please, correct me if I'm wrong and I probably am, but doesn't the overall waveform look similar to what it did before? When I zoom in on it though, the waveform looks much more like the good sample waveforms I've seen.
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Andy_ Super Nerd Picogroup Offline Posts: 1,398 DeMotte, IN Indiana USA Gender:	Re: First time user, fuel pump waveform. Reply #26 - Dec 23^rd, 2010 at 1:58pm Zoomed in.
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Mick

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Re: First time user, fuel pump waveform.
Reply #27 - Dec 23^rd, 2010 at 4:57pm

Andy_ wrote on Dec 23^rd, 2010 at 1:57pm:

Here is the pump after being replaced. Please, correct me if I'm wrong and I probably am, but doesn't the overall waveform look similar to what it did before? When I zoom in on it though, the waveform looks much more like the good sample waveforms I've seen.

There appears to me that there is alternator ripple wave mixed in with this fuel pump.

How were you hooked up Schumi?

How is the charging system?

Can you take a wave of alternator ripple?

Did the car work as expected after pump/filter replacement?

Mick

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Mick

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Andy_ Super Nerd Picogroup Offline Posts: 1,398 DeMotte, IN Indiana USA Gender:	Re: First time user, fuel pump waveform. Reply #28 - Dec 23^rd, 2010 at 6:44pm Mick, I was hooked up around the pink/black wire coming out of the inertia switch. The vehicle seemed to work as expected. Sorry, but it's gone now, so I can't get a wave of the alt. ripple. Is it possible that I had it hooked up wrong?
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Irwin

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Re: First time user, fuel pump waveform.
Reply #29 - Dec 23^rd, 2010 at 7:06pm

Hey there, I was wondering if this ford uses the fuel pump module. If so the fuel pump is pwm, it can vary the press. accordingly. The module recieves a pcm control input, pwr. and ground. It ouputs to the fp. It reports diagnostic info back to the pcm in 3 states, 25%, 50%, and 75% duty cycle. Each duty cycle % corresponds to a "normal op." pid or dtc. ATG has some pretty decent material on these, not sure about All Data or Mitchell. Ford started using these back in 99, so it may be on this explorer. The sedans usually have them located in the rr side of the trunk. Not sure about the suv's. Thought this may be useful to you if your'e not already aware of it.

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