3rd Generation Specific (1993-2002) 1993-2002 Discussion including performance modifications and Technical Support Sections.

Fuel Gauge not working...this might be why

Old 10-28-18, 08:02 PM
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NM Fuel Gauge not working...this might be why

In the years I've been a member of this forum, I've rarely made post because early on, I understood that since this car is so old, there isn't much that has happened to this car that hasn't been documented. I've learned to search the forums and since I'm an avid reader, the 2 go hand in hand. However, I need some advice. I've been reading about fuel gauge issues for a couple of weeks now, even talking to long time members of the forum in person about the issue. However, I did not expect this.

I've been riding with my gas-level gauge below E now for about a month (it partially worked before, going all the way up until about 3/4 a tank), and tonight I finally had time to pull the assembly out and examine it. I found the threads about disassembling and cleaning the fuel sending unit, so I was prepared to find something relating to carbon buildup on the actual assembly. I found this instead.







Aside from being the luckiest person alive and avoiding a possible catastrophic fire (I WILL be ordering an extinguisher TONIGHT), I'm just going to take a wild guess and say my fuel pump is pretty much fried, alongside the sending unit itself.

How much damage is done to this thing? Do I need to replace everything, or is it salvageable? Thanks in advance guys.
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Old 10-29-18, 08:39 AM
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With upgraded fuel pumps a number of people have noticed wiring failures going to the pump - there's too much current being drawn through those connectors and they are relatively small gauge.

Some people have documented ways to put new bulkhead connectors in. Since that connector is so burnt up I would look into that.

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Old 10-29-18, 09:00 AM
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Agreed. Looks like a walbro 400. In my opinion any upgraded fuel pump in the fd needs a wiring upgrade. The stock wiring is just too small of a gauge and combined with voltage drop in the system it will burn up the wiring. I change the pins in the stock connector to accept 10-12 gauge wiring and run a dedicated relay for any upgraded pump in the fd. BTW you can buy that whole assembly from mazda still. It will come with a new stock pump but you could always sell that.
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Old 10-29-18, 11:20 AM
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Originally Posted by IRPerformance View Post
...In my opinion any upgraded fuel pump in the fd needs a wiring upgrade....
Would this include even the mild upgrade of the p n p Supra pump?
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Old 10-29-18, 11:25 AM
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Ihor, do you have a source for those pins?

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Old 10-29-18, 12:44 PM
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In quite a few build threads I’ve noticed that people have rewired the harness for fuel pump upgrades, so I was under the impression that this was the norm. I bought the car like this and never bothered to check the wiring when he told me it was installed by a very reputable garage in LA. However, I’m finding more and more places they took shortcuts everyday. I appreciate the timely response gentlemen. Will be ordering a new assembly from Mazda ASAP.
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Old 10-29-18, 02:40 PM
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Originally Posted by DaleClark View Post
Ihor, do you have a source for those pins?

Dale
https://www.bmotorsports.com/shop/pr...oducts_id/1783

Its a little tight but you can get a 12 gauge wire in there.
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Old 10-29-18, 03:15 PM
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Originally Posted by Sgtblue View Post

Would this include even the mild upgrade of the p n p Supra pump?
I burned up my connector with a stock pump... suspect it is the cause of many a wankel's untimely demise.

Bypassed the stock connector and went with ATL fuel cells wire through bulkhead fitting.

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Old 01-10-19, 01:56 PM
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12 gauge wire is what is typically used for this upgrade? How many amps does the relay need to be rated for? Same as the stock one?

Thanks
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Old 01-11-19, 08:42 AM
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Originally Posted by NJ-JDM View Post
12 gauge wire is what is typically used for this upgrade? How many amps does the relay need to be rated for? Same as the stock one?

Thanks
12 gauge wiring or equivalent to what comes with the pump you are using should be fine. I use the Spal 40 amp relays. They have nice heavy duty wiring and come with the connector side already pinned.
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Old 01-11-19, 11:18 AM
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Originally Posted by Sgtblue View Post

Would this include even the mild upgrade of the p n p Supra pump?
In my opinion, yes. Others may disagree, but the voltage drop from a Supra pump installed on a FD with all original wiring is too much for comfort. I ran some tests last year on my car with the Supra and OEM pumps, and wound up going back to a new OEM and removing the Supra. YMMV...

https://www.rx7club.com/3rd-generati...-pump-1119325/

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Old 01-21-19, 09:55 AM
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Is everyone using a specific type of wire in the tank? The wire in my tank is 16ga and I'd like to upgrade it to at least 14 if not 12ga. What is your source for fuel safe/submersible wire? Not having any luck finding anything that is a straight forward solution from the usual parts sources.

Thanks


I kept digging and found a few places that will sell you the correct spec wire and/or various other pump connectors, etc. Racetronix and CJ Motorsports.

Last edited by NJ-JDM; 01-21-19 at 04:24 PM.
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