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Discussion Starter #1
okay. I posted about this earlier. I'm now on my second brand new fuel pump from rockauto. and the fuel gauge is still stuck and won't go past three-quarter tank. I now have the fuel pump out of the tank and hooked up and when the power is on and I move the float up and down the fuel gauge on the dash does not move.

any ideas?
 

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Most times there is a long delay between moving the float and the gauge reacting to the movement. This is done to prevent your needle bouncing around as you go around corners, stop and accelerate. It provides a smoothed "average" reading. Is it possible that you just moved the float around and didn't get an immediate reaction and moved onto the next step?

Otherwise, it sure sounds like a mechanically stuck gas gauge.
 

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Discussion Starter #3
i tried it awhile. and with the power to it and the float rock solid at it's lowest position, the gauge didn't budge.

how is a stuck gauge fixed?
 

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Discussion Starter #4
Oh, and I don't think it's mechanically stuck. When the ignition goes off, the gauge goes to empty. When I turn on the key, the fuel pump pressurizes and the fuel gauge shoots up to 3/4 tank. So it's moving on it's spindle at least. Just not in the right places! I'm stumped on this one.
 

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im thinking its an improper resistance issue in the sending unit thats giving you the false readings.if the aftermarket pump does not have the same resistance as the oem.watched a youtube vid on that subjest awhile ago.
 

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Discussion Starter #6
im thinking its an improper resistance issue in the sending unit thats giving you the false readings.if the aftermarket pump does not have the same resistance as the oem.watched a youtube vid on that subjest awhile ago.
Thanks. I'm calling RockAuto tomorrow and will ask about that.
 

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I just went to the manual to see what could be causing your problem, and I think I just figger'd it out...

I'll bet your MDX is a 2005 or newer, and I'm betting that the pump/sender that you have is for a 2004. That would give you the same kind of results you're getting - the 2004 sender at dead empty position will give the resistance that the 2005-6 sender will at 3/4 tank (give or take).

FYI - here are the resistance values you should be looking for (for both options):
115522


I just checked Rockauto, and it looks like some of the pump/sender units are different between the 2005 and 2004 models, but some (including the least expensive Ultrapower unit) are listed for both years (which can't be right unless they have some sort of configurable sending unit, which I doubt). My guess is that it's just a technical error that Rockauto (so probably lots of other vendors) haven't figured out yet.
 

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Discussion Starter #9
I just went to the manual to see what could be causing your problem, and I think I just figger'd it out...

I'll bet your MDX is a 2004 or older, and I'm betting that the pump/sender that you have is for a 2005-6. That would give you the same kind of results you're getting - the 2005-6 sender at dead empty position will give the resistance that the 2004 sender will at 3/4 tank (give or take).

FYI - here are the resistance values you should be looking for (for both options):
View attachment 115522

I just checked Rockauto, and it looks like some of the pump/sender units are different between the 2005 and 2004 models, but some (including the least expensive Ultrapower unit) are listed for both years (which can't be right unless they have some sort of configurable sending unit, which I doubt). My guess is that it's just a technical error that Rockauto (so probably lots of other vendors) haven't figured out yet.
Mine is a 2005. And I bought the US Motorworks pump. (US MOTOR WORKS USEP8640M Electric Module)
Thanks for the resistance information! That will help when I call tomorrow!

tom
 

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Oops - I got my models backwards, and your info pretty much confirms you've got the wrong (not your fault!) pump / sender.

What I should have typed (I'll edit my original message above to avoid future confusion) is:

I'll bet your MDX is a 2005 or newer, and I'm betting that the pump/sender that you have is for a 2004. That would give you the same kind of results you're getting - the 2004 sender at dead empty position will give the resistance that the 2005-6 sender will at 3/4 tank (give or take).

The pump / sender you got IS listed for 2004 (as well as - and inaccurately - for a 2005+). It can't work for both, so I'm betting its sending unit matches the spec for the 2003-4 unit in the chart I posted, which would return a 3/4 tank reading on an empty tank.
 

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Discussion Starter #12
ugh. the rockauto return process is slow if you already have a return in transit back to them.... I guess I would be okay ordering a 2006 pump from them?
 

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Jentink, I think you would be fine doing that - I'd suggest making sure that it's ONLY for the 2005+ model, and not listed as a fit for the 2004 model as well. Might not hurt to look up the detailed specs on the manufacturer's website if they have info on the sending unit resistance, but I suppose that might be like finding a unicorn! ;-)

FWIW, I've always had good luck with Rockauto returns - haven't had many of them, and IIRC I just ordered what I needed again rather than waiting for a replacement (I'm always ordering something from them, after all!!!). ;-)
 

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Discussion Starter #14
I'm trying to get them to address the year/part number issue. they have issued another return, but i have to pay shipping for their mistake. I sent the resistance specs from the above post, so we'll see what they say tomorrow. the part number usep8640m says for 2003-2005. usep8657m is for 2005-?

But at this point, if they don't address that problem and give me free return shipping, I'm going elsewhere.
 

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Discussion Starter #15
Wow. Several emails back and forth from rockauto support, but all they did was address my return. not one comment about the wrong part information, or even a comment saying "it's not a wrong part"....
terrible customer service.
 

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The folks you're dealing with for the return are no doubt different from the "spec-setters" that need to fix the problem.

It's curious, but the (very) quick perusal of pumps on eBay (easy to check those with application lists) make it look like the 2006 has a unique fuel pump part number, and the same one is listed as a fit for 2001-2005 on the others. Then you look at the chart from the manual, and it shows that the break is between 2004 and 2005, not 2005 and 2006.

You're kind of in a strange, gray territory here on this one, but given the many variables, it seems that there was probably a change-over mid-year in 2005, and the original one you had was the one that is listed for a 2006 model. It's not uncommon for parts to have a serial number cut-off range for a given year... I guess that's just something that never happened with the Honda / Acura fuel pumps.

These kind of oddball situations are generally lost on the kind of folks that online retailers hire to do customer service (they're probably not master diagnosticians). ;-) Maybe you can write to Rockauto management and see if you can get a refund on the return shipping.
 

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Discussion Starter #17
I checked oem part numbers. 2004 is 17045-83v-a50. 2005 and 2006 is 17045-s9v-a00. So I'm going to order a 2006 pump (not oem tho!). many of the sellers are getting this year split wrong. i think delphi got it right. they have different part numbers from 2004 to 2005.

rockauto must've know i was getting frustrated - i just got a discount coupon today.
 

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Discussion Starter #18
well, i went with the delphi for a 2006 mdx, and it works. (got it from amazon...still pissed at rockauto). it has a 4 pin connection. the wrong pumps had 5. the plug in the car has 5 holes, but one is blank.

how do we get info like this pinned on the forum? anyone with a 2005 is going to have the same problem...
 

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Congrats on the happy ending! Interesting about the different pin-out, and strange that your car has a connector that had a blank spot for a not-yet-designed "feature"...

I always try to include the keywords / info that's going to help those searching (on the forum, or the 'net in general). It's probably a little "specific" to make it to a true sticky, but hopefully those who have the same problem you did in the future WILL find this thread, which could hopefully save them a lot of trouble.
 
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