1G Help replacing relays on a Full Blown Hanger

[1cleangsx]

Hey guys, as the title states I’m replacing the relays/relay harnesses specifically because one of the relays kept getting HOT, now to preface this I didn’t wire any of this , my brother n law has always been in my corner to help with that, I’ve come a long way as I’ve done all the wiring so far for my auto swap, but anyways on to the pics

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My QUESTION specifically is if the power wire on the factory harness needs anything? The pumps are now both fed via an 8awg straight from the battery.

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As you see here, this power feed has an in-line 40amp fuse.

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In this pic you see things get fishy, the 2 yellow wires are the high current out 87 pin, the relay on the right has the 85 pin ground white wire going to a fuel pump ground wire like it should, the relay on the left has 85 pin ground wire (blue wire on that relay) going to what I believe is the factory power wire, the black wire with white stripe? Then the low current 86 from that relay going to the other pumps ground wire, I think he got pins 85/86 mixed up on that relay, again so Im wondering with the new harness is it necessary to connect the 2 low current pin 86 to the factory power? I know that wire isn’t feeding the pumps anymore, and also he just heat shrieked off the factory ground wire, all this aside I’ll mention the fuel hanger signal wires worked great, thanks guys for any input

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[1cleangsx]

Sorry the 3rd pic looks confusing, here’s a better one

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[1cleangsx]

After some reading on here I’ll be simply running the pin 86 (signal wire) back to the factory harness, which is what I think my brother n law meant to do, just got 85/86 swapped on that relay, I’ll report back..

Thread 'Simple Fuel Pump Rewire became a problem'
https://www.dsmtuners.com/threads/simple-fuel-pump-rewire-became-a-problem.541692/

This thread was very helpful

 

[Anfurnyy]

I used the factory ground to ground and trigger the Main relay, hook the rest of the wires up like your normally would.

Then I also used one of my ECU outputs to ground and activate the 2nd relay. Again hooking the rest up like normal.

This is the diagram I usually use

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[We're on Boost]

But if the system was working and the only problem was that the relay was getting hot ? then it seems like the problem is inside that relay (bad contacts with high resistance) or in the connector to it. Blade connectors get a little warm even if they are good. If they are not very good they can get really warm. Next time you use a plug-in-the-wall vacuum cleaner, pull the plug out of the wall as soon as you are done and you'll probably notice the plug is pretty warm.

What relays are you using anyway?

I haven't had any of my $5 aftermarket type relays fail yet but I have looked around a little bit trying to figure out what relay would be a step up hopefully in quality and reliability. I decided to buy 5 of these TE Connectivity 3-1393303-4 relays. Haven't used any yet so I can't exactly say I recommend them but if you get to looking for different relays, take a look. They are still just using quarter-inch wide blades for connection, so there still could be a problem with connector poorness when you are using those ganged connectors.
BTW the price on these right now ($12.66 each if you buy 5, or $13.67 if you buy 1) is the same now as it was in January when I bought mine.

 

[1cleangsx]

They’re just your average 40amp relay from Napa, I did try simply replacing the relay but the same thing happened, that was also before I looked at the wiring and looked up some basics on relays, then realized the one relay had the signal wire running to the pump ground instead of back to the factory harness like the other relay, it’s crazy the car still ran fine, but again I think he just got pin 85/86 mixed up on that one, no biggie.

 

[We're on Boost]

They’re just your average 40amp relay from Napa, I did try simply replacing the relay but the same thing happened, that was also before I looked at the wiring and looked up some basics on relays, then realized the one relay had the signal wire running to the pump ground instead of back to the factory harness like the other relay, it’s crazy the car still ran fine, but again I think he just got pin 85/86 mixed up on that one, no biggie.

Oh a NAPA relay should be ok, they usually sell pretty good stuff.

As for where the wires go, 85 and 86 don't care about polarity. One of them has to go to the factory power wire, the other one has to go to a ground. Doesn't matter which. And it could be any ground.
I saw your pic of the rewire in your build thread - it looks really good. I haven't tried to figure out where your wires are going though. Just enjoying it aesthetically.

Will it be a while before you figure out if it solves the hot relay problem?

Your pumps are supposed to both run all the time aren't they? Or are they staged? I don't remember. If you were accidentally running all of the high current through just one relay and the other relay was doing nothing, or the other pump was doing nothing, that could explain the one hot relay.

BTW here's my favorite diagram for showing the insides of a relay with the terminals numbered. It's showing the 5 pin type.

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[1cleangsx]

Yes my pumps run all the time, however you’re saying one of the signal wires needs to be grounded? If that’s the case then it WAS wired correctly , the way I re did has both pin86 signal wires going back to the factory harness power, each pump ground is connected to its own relay ground pin85, and those ground connections each have a posi tap connector grounding that connection to the car. Hopefully that works , I won’t be able to test it for awhile unless I decide to pump out the fuel in my tank currently

But in regards to how it was wired before something wasn’t right, if it wasn’t the wiring it could’ve been the pump who knows

 

[We're on Boost]

however you’re saying one of the signal wires needs to be grounded?

No. If the signal wire is what I'm calling the "factory power wire" then no. You can't run that to ground, it would short out that circuit in the car.

the way I re did has both pin86 signal wires going back to the factory harness power

That's right. Both 86's going back to the factory power wire. On my car, the factory power wire is black with a white stripe.

relay ground pin85, and those ground connections each have a posi tap connector grounding that connection to the car.

That's right. Both 85's go to a chassis or tank ground point.

each pump ground is connected to its own relay ground pin85,

This is ok. You brought the negative wires from each pump out through the lid so you need to ground them somewhere. You could attach those wires to any good solid ground. They will have a lot of current in them. If you attached them to the wires that go from the 85's to ground, that is ok as long as those 85's wires are a decent gauge. Like 14 gauge at least I would say. 12 gauge would be better.
I wish those pre-made relay plugs were made with 10 gauge wire in all 4 or 5 positions but I think they are usually made with 12 gauge, and they might even have smaller than 12 gauge on 85 and 86 because normally those 2 pins only carry the small current that runs the electromagnet that's in the relay, and that is going to be a really small current, like 14/90 = 0.155 amps. Tiny.
So at the point where a pump negative wire attaches to an 85 wire, from that point to ground should be a decent gauge like 12 gauge or 10 gauge. Going the other way from the attach point (back to the relay) the gauge doesn't matter, it can be whatever the 85 wire is that comes out of the relay plug.

 

[1cleangsx]

Good info! Each relay/pump ground connection T’s off with 10 gauge to chassis ground, those are the posi tap connectors you see in my current rewire.

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I also grounded the small factory harness ground as you see in the pic

 

[We're on Boost]

Each relay/pump ground connection T’s off with 10 gauge to chassis ground, those are the posi tap connectors you see in my current rewire.

These 10 gauge wires look good. The 8mm bolts they go to in the trunk floor are good solid grounds.
I'm a little confused by one of those bolts though - the one with a "4" on top, looks like a smaller wrench size than the one with a "7" on top. In my car those are both 8mm bolts with 12mm wrench size.

I also grounded the small factory harness ground as you see in the pic

This one might potentially be a problem. Because that Phillips head screw that it goes to, in my car that screw and the little metal bracket that it goes through are not a ground. I went out there again just now to check and I scratched the meter probe around on the metal bracket and the screw head and got infinite resistance everywhere on it. It's completely isolated. I don't know how. Seems weird. I use the meter as an ohmmeter doing this kind of check. The other probe I had contacting a known good ground, so I was expecting to see 0 ohms, but got infinite.
On my car that small black wire still goes to the original place on the stock tank lid, a little stud, I think a 4mm stud, with a nut. I checked it just now to make sure it really is a ground in the stock usage, and it is.
So you should check on your car to see if that Phillips screw is a ground or not. I don't know if it will even affect you one way or the other, maybe not. I don't know where that wire goes to on its other end. But it might be some kind of problem having that small black wire connected to something that isn't a ground.

 

[1cleangsx]

Thanks again! I know that wire originally was the ground on the factory pump hanger, on the last wire up my brother n law did he didn’t ground it to anything, not even sure if it’s needed but I’d prefer to ground it, I’ll find a better spot thank you

 

[Anfurnyy]

For reference this is how mine is wired.

Both relays get switched 12v from the black and white wire in the factory harness. That's the 12v supply from the MPI.

Primary relay grounded top left just to the chassis, power wires go directly to battery 10ga, and power wires to fuel pumps are also 10ga

Secondary relay ground is triggered by an aux output at my ECU, using the ground pin on the relay. Has the same 10ga from battery and 10ga to the fuel pumps.

Both fuel pumps are grounded via 10ga to the spare tire bolt, also where I have a chassis ground from the battery.

Factory ground is grounded to one of the studs on the top of the fuel pump hanger. I honestly don't think this needs grounded since the fuel pumps get their own ground and don't rely on the fuel pump hanger for a ground like factory.

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[1cleangsx]

This one might potentially be a problem.

Aand here’s the reason it’s not a good ground.

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Theres a plastic anchor underneath , thanks again for pointing that out