Hey guys, have an issue. I did the rewire as this guide for 2g AWD:



Now I eliminated stock connectors and am running a bulkhead fitting with the 5 wires connected directly. Before the rewire everything was perfect no heating of wiring or anything. After rewire, we rewired like diagram wired pin 85 ground wire to stock ground harness and the main power and ground wire were burning hot. As you can see in the attached pic is the red wire is + from pump and the red and black wire is the - of the pump. Then after, we replaced with 10gauge ground straight to ground on battery and the same wires are still burning hot after 5 minutes of running car. It heats up from before the blue connector, which is the harness side, not the pump side. A friend said it could be bad pump, but I don't see it as first of all it is a newer walbro 450 and it wasn't burning hot before the rewire. Am I missing something?

I also cut the stock harness ground as that is what I tapped into in the beginning and since I cut it to add the 10gauge to the ground of the battery, I just wired that stock ground wire to chassis, not sure if that is fine or not.

Recheck all of your connections. High resistance/poor connection will cause the wires to get hot. Look at the solid red wire where the butt connector is. It looks like copper outside of the butt connector. May be your problem.

Like above, check resistance, also check ground is actually grounded

You can measure if you have any voltage drop from one end of a wire to the other end (or across connections or butt joints) to easily find high resistance points under actual operating conditions (resistance measurements under no load doesn't always give you the true picture). These voltage drops should be near zero. Also measure voltage across fuel pump connector when it's running to see if you have enough.

how exactly would you measure votage drop from one wire? I replaced the ground from relay and put it on a strong chassis with no paint in the trunk. Same ground I'm using for negative on battery. It still heats up. I then replaced all connectors and ran them as one wire, the red and the black wires (the ones heating up from pic) Those blue connectors I replaced and still heats up. I then added another ground, the one from the stock harness I ran a 10gauge instead to the chassis, so now we have 2 solid 10g grounds and still nothing! Still burning hot, could this mean it is the fuel pump?

without a volt reading from each wire, it's hard to tell where the issue might be... so that info would help greatly..

i know this isnt what you want to hear.. but have you tried swapping back in stock connectors and see if problem goes away?

Yes you may have a short in the FP (or wires going to it). I suggest disconnecting the FP right at the relay and put two 12v incandescent headlights (so it will pull around 10 amps) in it's place to see if you still have the wire heating. If you don't suspect a FP (or wires going to it) short. In fact first you might want to quickly look at the FP wires going into the tank to see if they are shorting.

You should get rid of those spade connectors and solder the wires together.
Unless you have specific reason you used the crimp connectors ?
I wouldn't trust those in the long run that's just me though hah


Good luck on the diagnoses !

Yes soldering is always best on a vibrating car. If you decide not to at least cover up (heat shrink or electrical tape) that bare red wire sticking out.

luv2rallye said:

Yes you may have a short in the FP (or wires going to it). I suggest disconnecting the FP right at the relay and put two 12v incandescent headlights (so it will pull around 10 amps) in it's place to see if you still have the wire heating. If you don't suspect a FP (or wires going to it) short. In fact first you might want to quickly look at the FP wires going into the tank to see if they are shorting.

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Hmm a little confused here. Can you be more specific on instructions here? If it still heats up it means bad pump?

Also I removed spade connectors as well and I soldered still heating up.

If it heats up with two headlights connected in place of the FP, then you most likely have a short in the wiring somewhere (or you wired it totally wrong). In fact, a correction, the best place to connect the headlights (in place of the FP) would actually be right at the FP connector going into the tank. Either way it sounds like either a short in wiring or a short in the FP.

Watch my youtube video. I cover it pretty good i think.

I cant believe no one noticed this diagram is wrong. Here is the diagram for a 2g gsx rewire. I knew yours looked off so i checked it. Yours is missing a ground wire. That stock ground needs to run from connector to a ground wire.

Herehere

On a bosch style relay pins 85 and 86 are the two end of the relay coil and pins 30 and 87 are the normally open contacts. There isn't polarity so you can interchange the connections on either the coil or contacts without functional difference unless the relay has an internal diode across the coil.

Normally pin 30 would be the input you want to switch (+12 power in this case) and 87 the output and pin 86 the 12v source for the coil with pin 85 being ground side of the coil.

Based on the normal conventions the first diagram in the original post is the correct one.

You are absolutely correct steve. I didnt look at the pin numbers on the relay in my diagram. I figured they had em right on diagram. The diagram i posted was wrong haha. Good man Steve.

what gauge power wire did u run? maybe you have broken insulation on the wire someone allowing it to ground out and get hot.

GST Jeremy said:

what gauge power wire did u run?

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This is a key consideration. Some fuel pumps draw more than 20A when running.

Well I'm running the STM rewire kit:

http://www.streettunedmotorsports.com/parts/stm_fuel_pump_rewire_kit.htm

I believe they use a 10gauge or 12 gauge for that blue power wire. I replaced the thinner blue wire from that connector and used the thicker gauge blue power wire as one full wire instead of splicing. Hooked it up as in the diagram, the fuel pump I'm running is walbro 450 e85 version. I'm wondering if that is the culprit as it never used to heat up without the rewire. The ground from stock harness I put on seatbelt with a 10gauge and scraped off old paint. The ground from rewire is 10 gauge to the rear trunk chassis with no paint as well.

if you have the blue wire in the pic as your power wire then the gauge of wire is not your issue. its gotta be grounding out somewhere

JM1080, I am having this exact same problem on a E85 450 Walbro Pump. Except I actually had it get so hot it melted a section. Was the solution one of those listed above?

I had the same problem on my ground connection at the butt connector. The plastic jacket around the butt connector was melted and smoking. It was down to a bad connection.

My fix was to strip the wire ends long enough so that when I shoved the wires into the butt connector the ends of wire on both ends could touch and let the wire strands intertwine with each other tightly, then I crimped the butt connector and made sure it was nice and tight. After that the wires only get slightly warm, not hot at all.

Butt connectors are a no-no on anything that's more than an amp or two (I don't like to use them at all I can help it).

If you test voltage drops, it will tell you where the bottleneck is.

tametalon92 said:

Butt connectors are a no-no on anything that's more than an amp or two (I don't like to use them at all I can help it).

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The butt connectors were from the STM rewire kit. Someone should probably tell them to stop including butt connectors then.

tametalon92 said:

Butt connectors are a no-no on anything that's more than an amp or two (I don't like to use them at all I can help it).

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Please don't spread mis-information. Butt connectors and soldering are both OEM approved forms of connecting wiring.