Dakota Towing Burns Fuel Pump

1996 Dakota 3/9 5 spd MT:
This is my daily driver, and tow vehicle. I have been driving this truck since January 2010 and been suffering the same problem since. I got this truck at 220k miles, and now has 360k miles.

It started as fuel starvation when towing, then have to replace the fuel pump soon after. It has evolved to towing anything sustained over 35 mph burns the pump. It doesn't matter if I'm towing a 23 ft 5th wheel camper, 18 ft fifth wheel flat bed trailer empty or with a car, or the 5x8 dinghy trailer empty. I can't tow and sustain speed without burning the pump.

I have replaced all the sensors. The exhaust is low restriction. The fuel rail has been blown with air, the injectors tested with momentary 9V and blowing through them. The engine has been replaced twice, and included fuel components. Timing chain and valve components are good, compression tests good.

Fuel lines: Upper half seemed a little restricted, so I swapped with one a little less restricted. Lower half line blows clear. The lower half is shorter and has less bends. The pressure regulator comes with the new module every time. There is no return line.

Electrical: Fuel line wires clipped short at plug. Ground wire connected to good solid body ground. On/Off/On switch on dash gives option for factory wire feed or alternate: Connect to Key On 10 gauge at column, to 20A auto reset breaker, to 30A On/Off/On switch, and 12 gauge wire back to the pump.

Last pump failed while running on alternate wire feed only for life of the pump. Previous pump lived on factory setting entirely.

The tank is clean. I have had the tank out 3 times, and cleaned thoroughly. I have taken the bed off once. Now i access the pump through a hatch in the bed. I shouldn't need a zipper for this problem.

From memory:
Specs on the pump: 192 liters per hour. 90 to 115 psi
Towing at 60 mph, 12 mph is less than 7 gal per hour.

Pumps are from Advance Auto, Global Automotive, AM Auto Parts ...

What am I missing?

From my experience- get an OE fuel pump.

You didn't mention anything about replacing the fuel filter. Those still have an external filter mounted on the frame rail I believe. Every time I burnt up a pump on my high mileage Dakota it was because the fuel filter was clogged up.

I agree a million percent with sportfury70. Get a Carter or Mopar pump. Its like the Airtex and similar pumps are designed to fail at exactly 1 year and 1 day.

About only other thing to kill a pump is high volts or low volts. DC Inductive amp meter may tell you something like a Fluke 325

When you're towing are you letting the tank get to empty before refueling? The fuel actually helps keep the pump cool, I wouldn't let the gauge get below 1/4 tank before filling up.

There is no inline fuel filter. The two piece line runs from the tank outlet to the fuel rail with no filter. You can look up Fuel Filter on the parts store sites, but they don't have one because it's not there.

My digital voltmeter shows 11.5 volts when cranking, and 14.25 volts charging above idle with or without other electrical loads.

I tow with a full tank. Yes, the pump is cooled by fuel. Don't ever run dry.

That is exactly what I did because I know my 92 had one. Napa shows a fuel filter for the 96. I know they eliminated them at some point but wasn't sure exactly when.

napa link

The pump puts out a constant pressure no matter how clogged the filter gets, no way is the filter being clogged killing a pump. Now if your fuel filter is plugged your pump probably ate the same stuff and that is what killed it.

As for running the tank empty killing the pump, also hogwash, it has a resovoir of fuel in the pump housing to cool it. Also it is hogwash that it starts picking up junk off the bottom of the tank when you run it low, the pump ALWAYS sucks from the bottom of the tank, if it was picking up sediment it would also do it when full. I always run mine till the light is on and never have had a personal fuel pump go bad.

I also agree about the airtex being a huge pile of garbage, we had to refuse to use one because we were replacing ALL of them under warranty. We have not had any delphi fuel pimps come back yet.

My 92 has a filter in the left frame,my 97 does not have a external filter.

I would disagree with this. The 92 was a return system with the regulator at the fuel rail well after the filter. If the pump just puts out one constant pressure then why does it have a regulator? With a clogged filter the pump is working hard at it's maximum rate trying to push fuel through it all the time thus overheating it because fuel isn't moving through it. Hook up an electric fuel pump and plug off the outlet, see how long it lasts.