Weekly Waveform #13 - Fuel pump current testing with low amp clamp.

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Let's check the fuel pump current with a low amp clamp. This can be a good test to verify the current health of the fuel pump or help you identify an intermittent no start or low power concern. The fuel pump amperage should have a sinewave pattern with slight variations up and down. Pattern should repeat itself ever rotation of the pump. Counting the humps within your repeating pattern will show you how many commentator bars the fuel pump has. Many pumps will have 8 commentator bars but higher quality pumps may have more.
5-20ms sweep setting on the snapon scope with a 10-20 amp scale
50ms/div-200ms/div on the picoscope with a 10-20 amp scale
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The links below help support the channel at no additional cost to you. Thank you
relay bypass kit with current loop - amzn.to/3bOJPSA
60 amp PDI low amp clamp with banana plugs- amzn.to/3qznAW0
Cheaper hantek low amp clamp(I have never used this clamp) - amzn.to/2JwUC8x
20:1 attenuator - amzn.to/2JSicwl
10:1 attenuator for uscope - www.aeswave.com/Primary-Ignit...
probing set - amzn.to/3587E46

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Опубликовано:

16 янв 2021

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Комментарии : 16

@fmcalv4889 5 месяцев назад

Thanks you showed me what i needed to know so i can check my GMC truck

@theGADGETSplaylist 3 года назад

These weekly waveforms are adding up to a good body of work. Will serve people well as a reference. Numbering videos is very useful and it's something I'm glad I did also. Lots of dedication to producing these on top of your busy day. My hat is off to you, Chad:)

@jimmorton3009 3 года назад

Good stuff, My Friend

@wrenchposting9097 2 года назад

When I bench tested a Corolla fuel pump, it only pulled 2.5 amps! Squeezing the test hose to add a restriction got it to max out at 4 amps. Good pump as far as I could tell.

@Lambros_Stefaneas 3 года назад

Nice lesson. Thanks.

@duanedonaldson2262 3 года назад

Very nice stuff. For folks who don't have an amp clamp but do have a scope, would it be possible to get a procedure of connecting a multimeter amp probes in series with the circuit and use the scope to voltage drop the pump ground wire on 1V AC at about 50ms timebase to check overall amp draw and VD and commutator humps created by the VD can be used for math, etc?

@rickystrawhun2596 2 года назад

So what was the issue with the van? Bad purge valve sucking up fuel after filling tank?

@macdonaldsmotorworks 3 года назад

Hey Chad.. quick question: is there any difference between simply using an on-off switch with spade connectors on either end of the switch (and a loop of wire) compared to the relay bypass kit you've shown? You're simply trying to turn on the load side of the relay correct?

@ThePracticalMechanic 3 года назад

Correct. A jumper would do the same thing. The bypass kits just make it easier to perform and less chance of connecting to the wrong terminals. If the computer controls the relay and power is back fed to the computer it could cause damage. I did it for years with a jumper harness.

@sargetester99 3 года назад

Let us know what went wrong with the first amp clamp and what it takes to fix it, so that we don't fall into the same trap, please

@ThePracticalMechanic 3 года назад

It has performed perfectly since the video so it must have been operator error. I’m suspecting a loose ground connection to the scope cause me to see the signal in more of an AC coupled format.

@sunjoomoontube 6 месяцев назад

Thanks for sharing your insights. Relay jumpers are cool. Just curious if Hantek or Micsig 4 channel scopes are good enough for automotive diagnosis. What are your experiences?

@ThePracticalMechanic 6 месяцев назад

Many start out with those scopes because of the price point. Most will upgrade to a pico at some point. I don’t have any experience with those scopes so I couldn’t tell you how good they are.