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Old 24-03-2020, 23:51   #1
adriank
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Question JDM Evo 7 AYC pump causing voltage drop/oscillation. Please Help!

Hey guys,

I've been trying to figure this out for some time now, my AYC pump causes a large voltage oscillation when its pumping. (it always pumps after 50% throttle or so and turns on even in straight line) The voltage oscillation causes my dash lights to flicker/dim and my AFR goes up and down because the injectors areing seeing linear voltage at WOT. There have been a few others with the same problem on here but it never came to a conclusion. Another thing i noticed is when i have the engine off and ignition on and i step on the throttle, the AYC pump keeps pumping and never shuts off. Here is a thread with the same electrical problem.

https://www.lancerregister.com/showthread.php?t=506427

Any help is greatly appreciated!

Thanks
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Old 25-03-2020, 11:11   #2
TrickyDick
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The power circuit to the pump is quite simple and power is fed from Fusible Link 7 on the battery terminal block through a relay. This 100A fuse is (AFAIK) dedicated to the AYC pump. Also the pump ground is #10 which only serves the pump (and washer pump). So sounds like the pump is taking excessive current, not enough to blow fuse but enough to pull down battery voltage. I'm guessing you have boot battery with long cable which probably makes the effect of excess current worse on voltage to rest of system.

Could be a simple fault like a bad battery or corroded connector on battery - bet you've already looked at that though .

After that for me it likely a pump fault. Doubly so because it's on in many cases when it shouldn't be which suggests it's not generating pressure. Could also be sensor issue but then that wouldn't cause excess currents.

If there is no pressure then I'd expect some AYC fault codes. Have you tried flashing out any codes?

I'd be tempted to disconnect the pump and feed it directly from the battery and see what heppens when its running, ie does the voltage drop. If it runs and voltage is steady then a possible cable loom issue somewhere?

Hope that helps
Cheers
Rich
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Old 25-03-2020, 15:31   #3
richyx
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the issue is your pump need as rebuild

its drawing more current as its trying to turn a gear against internal corrosion, so more rsistance more current its drawing

another thing is its probably making enough pressure to show the system working too, which is about half its operating pressure

whip the pump off and see whats its like inside bet the centre housing has corrosion where motor bearing sits and corrosion on drive plate

unless its been refurbished but still can be a duff motor
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Old 25-03-2020, 18:37   #4
adriank
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Thanks for the reply guys! I really appreciate it, looks like its time to pull the pump out and rebuild it. Can anyone recommend a website where i can buy the rebuild kit and new pressure sensors?
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Old 25-03-2020, 19:01   #5
leeslancer8
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Quote:
Originally Posted by adriank View Post
Thanks for the reply guys! I really appreciate it, looks like its time to pull the pump out and rebuild it. Can anyone recommend a website where i can buy the rebuild kit and new pressure sensors?
Just post it to the man above he’s not cheap but does a great job. Piece of mind then with a warranty etc
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Old 26-03-2020, 01:23   #6
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Originally Posted by leeslancer8 View Post
Just post it to the man above he’s not cheap but does a great job. Piece of mind then with a warranty etc

not doing anything at moment with whats going on in the world lol

buy rebuild kits off evoloution hydraulics but unsure if hes posting being we are on lockdown
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