Bad electrical connector inside fuel tank

Hey guys, this past winter I replaced the fuel pump in my 2005 RC, but it also turned out I had a bad connector inside the fuel tank. So I thought I'd post about it so that others might be aware of this potential issue. Summary: the fuel pump wiring connector inside the fuel tank was corroded; so the fuel pump was intermittently losing power.

First off I want to say thanks for all the helpful advice on this forum. I've been lurking for a bit over a year, since I purchased a 2005 regular cab 4WD. I've been driving Toyota pickups for over thirty years but this is the first one I've owned that wasn't a 4-cylinder. So, lots to learn, and this forum has really helped out, as I like to do almost all maintenance and repairs on my vehicles.

The fuel pump issue developed in classic fashion; no warning whatsoever. I was 40 miles out of town, coming home from a day of snowmachining, pulled into a gas station, and then she wouldn't start. Eventually we got it started with my buddy kicking the gas tank while I turned the key. Twice on the way home it quit for a second or two; anxious moments but it came back each time and I was quite relieved when I finally pulled into my driveway.

After doing some basic diagnostics everything pointed to the fuel pump, so I ordered up a Denso pump and strainer, and a new gasket. Having a regular cab is nice - once you pull the bed off the gas tank is very easy to get to. I cleaned everything up, pulled the old pump, popped in the new one, turned the key, and ... no start.

I had briefly hooked the new pump up to 12V before putting it in, so I was sure it worked. And I was getting 12V to the tank. I put 12V directly to the tank connector and couldn't hear the pump; checked the resistance and it was an open circuit. So I opened the tank back up and started checking things.

The culprit turned out to be the electrical connector inside the tank. Wiggle it a little, the pump gets power, wiggle it again and poof, open circuit. The brass contacts on both sides were black and crusty. So I pulled the connector apart and cleaned it carefully with jeweler's files and fine wet/dry paper. It seemed a bit loose so I crimped it ever so lightly until it maintained contact.

After putting everything back together; vroooom!, she fired right up. It's been four months and no problems. Hopefully this helps someone out there. I'd recommend that anyone replacing a fuel pump check that connector carefully.

 

Amazing post and great pictures!!!

 

That’s awesome. Wonder how the corrosion got to it, but at the same time, we’ve seen where the sender on the pump housing will have a dead spot in it for folks and just register empty at a certain level, due to corrosion on/in the contacts on the sender.

I believe when we looked up prior, if you buy the pump from Toyota, it’s Denso, but they give you the entire housing, with frame, pump, new sender and everything, and I believe that’s why it’s significantly more expensive. May be an option if you find yourself having issues again.

 

Thanks, guys!

Yeah, the Toyota pump is ridiculously expensive because you have to buy the whole assembly. The Denso pump came from Rockauto, and it came with the strainer attached. The old strainer, by the way, was pretty full of black powdery gunk (you can see it towards the bottom of the 4th pic). But the inside of the tank was almost spotless, so I guess that strainer works pretty well.

I was able to find a part number for the little pigtail wire, but it is discontinued by Toyota. I placed two orders for 'in stock' items that were later cancelled. Even though some Toyota dealers showed it in stock there don't seem to be any out there. Hence the very meticulous cleaning and crimping of those tiny brass parts - I had no other option, really.

The fuel pump connectors were still bright and shiny; they are always submerged. The corrosion was only on the brass parts near the top of the tank in the vapor space. I couldn't really say why.

I still don't know for sure if the old fuel pump was bad, or if the connector was the problem all along. The old pump spins when hooked up to 12V but I haven't flow tested it or anything. It's possible that the connector worked fine (despite being corroded) right up until I took it apart.

This site was really helpful in identifying the problem and helping me source parts. Thanks again!

 

You may be able to get the part direct from Japan via www.Amayama.com

And yeah, the screen has to be good … neither the ‘05 nor the ‘06 have a fuel filter, so that screen is a major line of defense against particular that could name an injector.