Third lift pump failure in 186,000 miles!

[seafish]

12.38 V no load measured at pump
11.4 V with pump running measured at pump
Nearly 1 V drop, almost 10%. If it were AC that would be unacceptable as 5% is the conventional limit. I finally found a recommendation of not less than 3% for 12 V automotive systems. We are way over that in this case.

Again, measuring the unloaded voltage at the point of use only indicates that the switch is on. It does not indicate if there is enough current to operate the appliance without over heating.

Bigger wires will be installed to the new pump and the old pump is going away.

EXACTLY...good job !!!

 

[Sequoyah101]

Thanks. I believe this could be the culprit to failure of pumps, low voltage delivered to the running pump. Too much voltage drop in the line.

All that checking voltage on an unloaded line means is that you have some kind of power but can't move enough amperage at rated current to prevent over heating of the motor. When the motor runs at higher heat than intended it eventually fails at some point from accumulated damage. It fails faster in the summer, just like the last two pumps I have had fail?

I speculate that Dodge people figured this out and increased the wire size or something to the tank mounted pump in post '05 models. For '02 to '04.5 well, they used what they had and built a patch and it works like a patch, not well.

I just came in for lunch and am making a test pigtail to eliminate as much resistance in the test rig as possible to verify the voltage drop of the running pump motor.

 

[BigPapa]

The power wire on an ‘05 from the relay to the pump starts out as a 16 gauge and goes to a 14 gauge. The ground wire from the pump starts as a 12 gauge and goes to a 14.

 

[mfurrh55]

When i put a new injection pump on my 01, i also installed the intank pump and it came with an extension wiring harness that was just plug n play, never had any problems with wiring., hope you get it figured out

 

[Sequoyah101]

Have not yet checked the wire size but I'm pretty sure the one from the battery to the relay is nowhere near a 12 or 14. I'll check tomorrow.

God voltages a little higher with the engine running and much shorter soldered test jumpers but still have similar voltage drops loaded vs. not loaded. Thing is, the voltages were over 12.

 

[SSage]

I would like to see at least 12 volts just on batteries. Remember a fully charged set of batteries is about 12.70 if they are healthy, when you turn that ignition there are a few things drawing down the battery voltage. When the truck is running you will see over 14 volts near the alternator. Mine runs at 14.6 volts usually. My AirDog 165 is powered off the battery terminals on the drivers side, the stock wiring controls the relay. Its been many years since the install, it hasn't had any issues yet.

 

[Sequoyah101]

Taking some time to get all done with the swap to the FASS. In no particular hurry right now anyway. Eventually need to go get a load of fertilizer sooner than later but need a little rain to go with it and that isn't coming right now.

Anyway, problem with the fuel gauge after taking the pump and sending module out to put the draw straw thing in. More on the draw straw when I finish all this.

I've looked at postings and see one other fellow had trouble after he installed his FASS. Appeared to be dirty connections. Looked at other postings but see no solutions only that cycled the key etc and it started working. Hmmm.

I've checked the line and get resistance with the key on and at the connector so something is working to the connector to the module at the tank.

Pulled the module and get resistance changes from 25 to 135 or so something so the Whetstone Bridge is working so I should be getting a fuel gauge reading.

Maybe it will work when I finally start the truck.

Happy for any information from the Dodge Mavins on the board with any clue how to figure out why the fuel gauge is not working?

Should be very low voltage drop to the pump now since I've put in 12ga wire with all soldered connections all the way from the hot side and the ground of the battery.

Did not like the clearance up by the starter on the frame mounting so moved the pump back to in front of the fuel tank high on the inside of the frame near the transfer case.

Has anyone ever seen a device that will swedge fuel line and make that smooth bubble that fuel line hose fits over so the clamp will have something to hit? I'd like to cut the factory steel line and splice the pump in instead of using rubber hose the whole way and just keep the fitting and line from the pump forward.

 

[Ozymandias]

There are barbs to tube fittings you can buy.

Check this out as a suggestion what to look for.
Amazon product ASIN B07DJ451LM

 

[BigPapa]

https://www.jegs.com/p/Earls/Earls-EZ-Beader/1140092/10002/-1

 

[Sequoyah101]

An answer but pricey!

I think I'll try the brake line fitting angle if my crimper is the right size.

 

[Sequoyah101]

For soft aluminum tubing only. Rats.

 

[jghflys]

Here is some info from a manual that says how the Fuel sender works. 2005 3500


Sensor-Fuel Level Sending Unit


The fuel gauge sending unit (fuel level sensor) is attached to the side of the fuel pump module. The sending unit consists of a float, an arm, and a variable resistor track (card). The fuel transfer (lift) pump is also attached to the fuel pump module.

For Fuel Gauge Operation: A constant input voltage source of about 12 volts (battery voltage) is supplied to the resistor track on the fuel gauge sending unit. This is fed directly from the Engine Control Module (ECM).

NOTE: For diagnostic purposes, this 12V power source can only be verified with the circuit opened (fuel tank module electrical connector unplugged). With the connectors plugged, output voltages will vary from about 0.6 volts at FULL, to about 7.0 volts at EMPTY. The resistor track is used to vary the voltage (resistance) depending on fuel tank float level. As fuel level increases, the float and arm move up, which decreases voltage. As fuel level decreases, the float and arm move down, which increases voltage. The varied voltage signal is returned back to the ECM through the sensor return circuit.

Both of the electrical circuits between the fuel gauge sending unit and the ECM are hard-wired (not multi-plexed). After the voltage signal is sent from the resistor track, and back to the ECM, the ECM will interpret the resistance (voltage) data and send a message across the multi-plex bus circuits to the instrument panel cluster. Here it is translated into the appropriate fuel gauge level reading. Refer to Instrument Panel for additional information.