Co_94_PU

iTrader: (-1)

Unplug the COR, unplug the pump, measure resistance on fuel pumps power wire it will indicate short to ground... Run new wire from pump to COR (fuel pump relay)..

Done.

Drewandhis89Yota

Just_ Rollin'

I think the fuel pump was dead. I worked the fuel tank out enough to shimmy the pump assembly out. Tested it on 12 volts and the wires melted/pump did nothing. Hopefully my 12v 1amp car charger that I used to test wasn't a stupid idea (too much juice?) but nevertheless, it seems like this is the culprit so far. I'll solder in some new wires with a new pump and see where that gets me.

Co_94_PU

iTrader: (-1)

You were not specific. Did you test the pump directly after removing it from the carrier bracket (pump "wire/pig tail" direct to power supply)?
You say solder in some new wires so I'm leaning towards no..

Best double check the specs and settings for that charger, maybe even the outlet.. Somthing isnt right there. Even a typical trickle charger output is more along the lines of 1.5amp, and those are designed for "maintaince" charging. This is not enough to melt a 17-14 guage wire or wire sheath.

You've got a dead short to ground (near zero ohms, as mentioned probably in the pump assembly/hanger where it goes into the tank), this is more than a burned out pump will draw (a burned out pump will pull no current). Typical start up current will have a momentary spike of 15-20amps and settle around oh maybe 5-7 from memory.

This does illustrate a good point and that is if you are going to do electrical work you need a meter, not only need to have one but need to use it to verify everything before you connect anything.

Just_ Rollin'

Sorry for not being more specific. I was wrong anyhow since I tested things more thoroughly today in sunlight and my pump works fine on direct 12v applied by trickle charger at 2 amps. Even the melted wires on the top of the pump assembly, though bonded together, work to actuate the pump if I attach the charger leads to them. Not sure exactly what I did the first time, but the pump is fine. Regular old trickle charger on 120v household outlet at 2 amps.

I didn't have time this go around to mess with the multimeter. But, seems like since the wiring and pump are fine (I will replace them anyway since they are out of the car) it must be wiring or something found from the tank to the ocr.

When I put the key in the ignition and turned to on position, the pump didn't do anything. So I will do this again and test the wiring here if I jump it, this should tell me of the OCR is OK or not. I think tomorrow I will try to jump the +B and Fp again and see if that kicks on the pump.

scope103

Good. It's not supposed to do anything, until you turn the key to STArt.

Just_ Rollin'

Well this is odd.....I tried to start the car while holding the fuel pump in my hand, confirmed it was working. Then go to check the fuse and it WAS NOT blown. The jostling of the cables must have sorted something out...but this is odd since all I did was drop the fuel tank.

I am going to solder in some better wire on the fuel pump assembly since as I mentioned, it was melted. Does size of the wire matter much as long as its a close approximation? I have some 18AWG laying around, which is close to the fuel pump assembly wiring that has the dongle attached.

Co_94_PU

iTrader: (-1)

Yes size matters. Even if it's a tiny little one inch piece.. More importantly it's not clear what you are thinking of replacing. Do not put some random sized unknown sheathing type wire in the fuel tank. Even outside the tank you want really good wire, it's exposed to all kinds of nasty crap..

Not uncommon for a bad wire to start functioning where you start moving it around, don't expect it to stay good.. Find the problem and fix it..

Just_ Rollin'

The inside of the tank wire looks fine, won't be touching this. I already cut the outside the tank, fuel pump assembly wire since it was fused and melted. This is the wire I would be replacing. I followed the wires as far as I could and didn't notice any obvious issues. I am thinking its the connector pieces or the old wire since as you say it was badly exposed to the elements.

I can't make out what gauge wire the OEM stuff is. But I do want to replace it at least on the outside of the tank.

RAD4Runner

Double-check insulation of all wires leading to AND IN fuel pump for possible shorts.

IF, and only IF, no one can tell you OEM wire gage,
Look at fuse rating that powers the fuel pump (EFI?). See what wire size should be used for that current.
Check diameter of stock wire you are replacing = that will give you idea of what AWG it is.
Use the bigger of the above.

scope103

He-he. Anyone who has ever struggled with the National Electrical Code knows that specifying wire gauge is non-trivial (voltage drop, insulated, enclosed, ....)

This site http://info.waytekwire.com/blog/auto...e-gauge-guide/ suggests that 18ga wire would be good for 7' with 5amps. I don't know the amperage draw of the fuel pump (my guess is <4amps), so you should just check that with your multimeter before you start hooking up new wire.

[But wait, someone will (should) point out. The fuse that protects the wire is 15amps. Shouldn't the wire be sized for that? The chart is based on voltage drop to keep the pump running well. If there is a short that pulls 14.9 amps through the wire, the voltage drop will be greater, but the temperature rise should be to less than 90°C and the insulation on THHN wire won't melt.]

The fused insulation, obviously, was due to a short. It probably pulled "about" 15amps, which was enough to melt 90s era insulation just before the fuse blew. If you can figure out the OEM wire gauge and can get that with THHN insulation, that would be best. If you want to sleep better, 14ga wire with THHN can carry 15amps all day without complaint. (House wiring for 15amps is 14ga.)

Just_ Rollin'

Wanted to circle back. Everything works fine now. I soldered on some new wiring around the top of the gas tank. This seems to have fixed the issue. I also made sure everything is well insulated.

I hope this post and everyone else who replied, will be able to help someone else.