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

Andy_ Super Nerd Picogroup Offline Posts: 1,398 DeMotte, IN Indiana USA Gender:	Re: First time user, fuel pump waveform. Reply #30 - Dec 23^rd, 2010 at 7:25pm Hi Irwin, this vehicle does not have the electronic returnless with the FPDM on it, but I have dealt with those on other vehicles. Thanks for your help though, I appreciate it.
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Mick

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Re: First time user, fuel pump waveform.
Reply #31 - Dec 23^rd, 2010 at 8:51pm

Andy_ wrote on 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?

It sounds as if you hooked the amp probe up ok,
I dont have a diagram right now.

Mick

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Mick

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crackerclicker

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Re: First time user, fuel pump waveform.
Reply #32 - Dec 24^th, 2010 at 11:32pm

Irwin wrote on Dec 23^rd, 2010 at 7:06pm:

If so the fuel pump is pwm, it can vary the press. accordingly

i see an opportunity here to derail the thread for just a moment Grin

.

for anyone that hasn't messed with the electronic returnless systems, check this out: http://members.iatn.net/forums/search/search.aspx?action=viewthread&m=18379&t=18...

good thread by some whacked out "cult leader" Wink

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Randy H. Super Nerd Picogroup Offline Tools are only as good as the Tech holding them Posts: 1,693 Bardstown, Kentucky Kentucky USA Gender:	Re: First time user, fuel pump waveform. Reply #33 - Dec 28^th, 2010 at 8:15pm Hello. Mick wrote on Dec 21^st, 2010 at 4:30pm: This pump apears to be spinning real fast at 7326 rpm. I am wondering Mick, how do you know how fast the pump is rotating by looking at the waveform? Is it a math formula you could share? Or something I don't know about the scope's software?
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crackerclicker

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Re: First time user, fuel pump waveform.
Reply #34 - Dec 28^th, 2010 at 10:05pm

Randy H. wrote on Dec 28^th, 2010 at 8:15pm:

how do you know how fast the pump is rotating by looking at the waveform?

i know i'm not mick

, but figure it's safe to answer this one. the easy way to get rpm is to pick the two similiar looking humps in your waveform and place your cursors on them. then simply look in your rpm box on the lower right. these two humps will generally be around 8 humps apart (representing 8 commutators in the fuel pump).
the two images below illustrate this.

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rpm.jpg (Attachment deleted)

similiar.jpg (57 KB | )

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Randy H. Super Nerd Picogroup Offline Tools are only as good as the Tech holding them Posts: 1,693 Bardstown, Kentucky Kentucky USA Gender:	Re: First time user, fuel pump waveform. Reply #35 - Dec 30^th, 2010 at 1:25am Thanks CC. I know you aren't Mick that was just a generalization. I meant basically anyone that could answer my question. I never knew that - and honestly never noticed that on the screen before! Thanks man.
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Davidlee

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Re: First time user, fuel pump waveform.
Reply #36 - Dec 31^st, 2010 at 4:34pm

Randy H. wrote on Dec 30^th, 2010 at 1:25am:

Thanks CC. I know you aren't Mick that was just a generalization. I meant basically anyone that could answer my question. I never knew that - and honestly never noticed that on the screen before! Thanks man.

Have not had a chance to use the Pico software for a fuel pump current yet, I am use to the good old calculator method!

It just keeps getting better

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PaddyIreland

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Re: First time user, fuel pump waveform.
Reply #37 - Jan 2^nd, 2011 at 8:47am

I am surprised there was so much discussion on this. The waveform provided in the first post is all over the place.
What you are looking at in a motor current waveform is the change in current as the brushes move from segment to segment on the armature commutator. Each winding should have approx the same resistance so current for each segment should be very close..
A rule of thumb that I use is the difference in peak current from lowest to highest shouldn't exceed .5amp. and us usually much less.

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Sam1

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Re: First time user, fuel pump waveform.
Reply #38 - Jan 11^th, 2011 at 11:38am

Hello techs;

I hope it is OK to post this here instead of starting a new thread.
It is a very similar case for another Ford (98 Faclon AU 4.0L VIN. W) "Australia"

The image file is for the fuel pump amp. (I think it is a candidate for a replacement) the customer is going for a cross state trip.
The data file is for the volt and amp for both the pump and the alternator.

What do you think?

P.S. whenever I use the filter the sample rate drops to 2MS no matter how high I set it. Is that OK?

thx

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fuel_pump_and_alt_volt_and_amp.psdata (4970 KB | )

fuel_pump_crank_to_run.gif (22 KB | )

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kennyp

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Re: First time user, fuel pump waveform.
Reply #39 - Jan 16^th, 2011 at 1:24pm

sorry guys i know its a bit on the late side to reply to this thread though what i was wondering was

if we had fuel cavitation such as fuel pump drawing air into the system wouldn't we get a waveform like the above which showed amps up and down though am i right in thinking that if there is no pattern in the wave noticeable then that could be a drawing air problem

sory to be such a newbie

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PaddyIreland

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Re: First time user, fuel pump waveform.
Reply #40 - Jan 16^th, 2011 at 4:16pm

kennyp wrote on Jan 16^th, 2011 at 1:24pm:

sorry guys i know its a bit on the late side to reply to this thread though what i was wondering was

if we had fuel cavitation such as fuel pump drawing air into the system wouldn't we get a waveform like the above which showed amps up and down though am i right in thinking that if there is no pattern in the wave noticeable then that could be a drawing air problem

sory to be such a newbie

No, you have to look at the timing as well as the waveform.. That pump is turning approx 1 turn every 20 ms. You can see the current draw from each segment on the armature and in my opinion that pump is no good. If there was a varying load on the pump it couldn't vary the pressure at such a fast rate. You would have to take a capture at a longer time base to read what you are talking about.

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Sam1 Super Nerd Offline Posts: 759 Gender:	Re: First time user, fuel pump waveform. Reply #41 - Jan 16^th, 2011 at 9:48pm kennyp wrote on Jan 16^th, 2011 at 1:24pm: fuel cavitation such as fuel pump drawing air I think that will make the pump run faster and draw less amps. "Tom's Nerds DVD series" has an example of such.
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kennyp Guru Member Offline Posts: 325 ecosse Scotland Gender:	Re: First time user, fuel pump waveform. Reply #42 - Jan 17^th, 2011 at 1:25am cool guy's thanks for that
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