Fuel Pump?

[Colorado Yeti]

The cube-shaped connector with the 4 pin slots in a square pattern is an old style that was problematic. The pins were too small (as in borderline functional) to pass the current required by the fuel pump. When the pump got a little aged and began pulling more current, this exceeded the capacity of the pins and that connection got hot and burned, further reducing the current it could pass which further starved the pump motor for power which made it pull more amps and run hotter... and the cycle continues until the connection totally burned up or the pump motor burned up.

It was upgraded to the flat 4-pin connector. Replacement pumps, both factory and aftermarket should come with the new connector and it's mate with a pigtail of wires and weathertight butt splices. I still preferred to solder and heat-shrink them when I changed them.

You hit the nail on the head here. I ended up buying the Carquest pump with the upgraded flat 4-pin harness. When I spliced into the original harness, it was very hard to strip the wire, as if it had become hot in the past. I have to say that this was one of the most unpleasant automotive jobs I have ever done and I have done a lot. I have a very low ceiling in my garage and couldn't jack up the vehicle to do this. The new pump did not want to press in using the new o-ring so I had to reuse the one off of the original pump and eventually it pressed in after applying a huge amount of pressure. That said, I was amazed how clean everything was after I pressure washed the under-carriage. I don't think this truck has ever been exposed to salt and it's clean as a whistle underneath. The new pump is way quieter than the original one, so I think it was on it's way out as evidenced by the blown PCM fuses.

 

[iamdub]

You hit the nail on the head here. I ended up buying the Carquest pump with the upgraded flat 4-pin harness. When I spliced into the original harness, it was very hard to strip the wire, as if it had become hot in the past. I have to say that this was one of the most unpleasant automotive jobs I have ever done and I have done a lot. I have a very low ceiling in my garage and couldn't jack up the vehicle to do this. The new pump did not want to press in using the new o-ring so I had to reuse the one off of the original pump and eventually it pressed in after applying a huge amount of pressure. That said, I was amazed how clean everything was after I pressure washed the under-carriage. I don't think this truck has ever been exposed to salt and it's clean as a whistle underneath. The new pump is way quieter than the original one, so I think it was on it's way out as evidenced by the blown PCM fuses. View attachment 239998 View attachment 239999

Glad you got it fixed! Something else I never liked about this generation is the location of the ground for the fuel pump. On the S-series (S10, Sonoma, etc.), it was at the back of the left frame rail, just in front of the bumper mount bracket. It was shared with the tail light ground harness. They had an electric motor that pulled a decently strong current fed with thin, borderline adequate wiring, then put the ground point about 5' away (wiring length). Oh, then topped it off with a connector at the pump bulkhead that could barely carry the current with the pump being new and operating at it's maximum efficiency.

When I relocated the battery on my S10, I ran a 10 gauge wire from the battery positive to a high-amp (40A or 50A?) weathertight relay (factory Hella cooling fan relay and socket from 90s Ford at the junkyard) and used the factory fuel pump power wires to trigger the relay. So then the factory fuel pump power circuit had a load of only a few milliamps instead of ~5-8 amps. It was a Walbro high volume pump, so it pulled more than stock and had larger wiring that I continued with through the bulkhead. Feed an electric motor all it needs and you'll maximize it's life.

 

[Colorado Yeti]

Glad you got it fixed! Something else I never liked about this generation is the location of the ground for the fuel pump. On the S-series (S10, Sonoma, etc.), it was at the back of the left frame rail, just in front of the bumper mount bracket. It was shared with the tail light ground harness. They had an electric motor that pulled a decently strong current fed with thin, borderline adequate wiring, then put the ground point about 5' away (wiring length). Oh, then topped it off with a connector at the pump bulkhead that could barely carry the current with the pump being new and operating at it's maximum efficiency.

When I relocated the battery on my S10, I ran a 10 gauge wire from the battery positive to a high-amp (40A or 50A?) weathertight relay (factory Hella cooling fan relay and socket from 90s Ford at the junkyard) and used the factory fuel pump power wires to trigger the relay. So then the factory fuel pump power circuit had a load of only a few milliamps instead of ~5-8 amps. It was a Walbro high volume pump, so it pulled more than stock and had larger wiring that I continued with through the bulkhead. Feed an electric motor all it needs and you'll maximize it's life.

You make an excellent point. Sometime we forget that the quality of the ground is equally as important as the delivery of the amperage.

 

[iamdub]

You make an excellent point. Sometime we forget that the quality of the ground is equally as important as the delivery of the amperage.

The circuit is only as good as it's weakest path.