Fuel pump issue

[Danger18]

2015 LS xr4036hc
problem: electric fuel pump does not operate with ignition in on position, nor after starting. Disconnected the fuel pump and applied 12 volts to the pump with a portable battery and it operates. Checked the power source wire connector and there is power there. I had already purchased a replacement pump and connected it to the power source to check it and it didn’t run. Makes no sense. The tractor starts and runs normally until under load. Then, it bogs down and takes a while to spool back up. My understanding is that it gets it’s run command from the ecu. I’ve checked the chassis for broken ground wires. Does anyone know how many and locations of the key grounds? Except for the Battery negative cable going to chassis ground, I cannot find another. Seems to me there should be a ground strap from the engine to chassis. HELP!

 

[alexpops]

What are your voltage readings at the connector? All fuses test good?
Could be corrosion somewhere in the circuit creating resistance & lowering the voltage enough for the pump to not kick in. If you go to the LS Tractor home page & click on parts at the bottom, you can look up the schematics. may take a little digging, but the parts list has some ok diagrams

Parts - LS Tractor USA

LS Tractor USA

lstractorusa.com

 

[Avenger]

Are you getting any codes?

 

[Danger18]

No codes. I actually think it has never worked since I bought it used 7 years ago. I’ve always thought the tractor lacked power. Doing some reading. The ecu, fuel pump and air pump are on the same fuse (#9). Checked that fuse. There is a 10 amp use there where a 5 amp fuse is specified. The air pump and fuel pump share a common ground. What baffles me is that the source wire is hot but the pumps won’t power up on it, though they will on battery power through alligator clips.

 

[Danger18]

Now I have to check the air pump. This could be the cause of my often and long regens as well.

 

[Danger18]

Oh, and it’s an xr4046, not 36

 

[RustyA]

Quite often especially in automotive the modules are powered constantly and the PCM/ECU provides the ground to energize the module. Not sure if this will help you in this case?

 

[alexpops]

See if it powers up in glow plug mode. I don't have a feeder pump on my xr4150, only the main injector pump, & it simply draws from the tank when the line is primed ... so that may be for priming the fuel filter on change or at start. If you think it's starving for fuel under load, the intake screen in the tank could be blocked. Try blowing it out with an air line or reverse the flow from the return to the line feeding the fuel filter using one of your fuel pumps & the spare battery jumpers. (or dip a fuel hose in through the fill as your source for reversing the flow) When did you change the fuel filter last? Is the tank full or near empty? I find I have fewer fuel starvation issues when the tank is full. Feed comes from bottom of tank & climbs to fuel filter inlet, so the static pressure may be overtaxing the pump until it catches up. (could also explain the higher fuse rating if the overtaxed electric pump was blowing fuses) If you have good flow/decent static pressure from the tank being more than 1/2 full ... the electric pump shouldn't be necessary.

 

[alexpops]

The too often regen is a common complaint in that series. They wound up redesigning the system for tier 4 final (41xx series), & lots of folks use the rebar approach to fix the regen issues in that particular series.

Final bit of advice ... I've had better luck with the WIX/Napa filters than OEM filters. Keep a few on hand since a single bad fueling could plug things up. Wix/Napa have better QC than LS in my experience. 2 ls filters lost the threads inside the filter for attaching the water sensor due to bad welds/brazing & couldn't be used ... never had that with wix or napa.

 

[alexpops]

Did this get figured out? What was fix?