Fuel Pump not coming on

[powersculver]

Today I was driving and my 2001 100 series just stopped on me. Fired up with starter fluid after pooping out, so thought it had to be fuel system. Fuses for fuel system are good, so I put a new fuel pump in. The new fuel pump won’t come on, what could be causing this? Pretty sure I wired new pump in right with new harness but here’s a pic in case I didn’t.

 

[medtro]

How did you test the fuel pump? Did you turn and hold the key and let the engine cranks?

 

[flintknapper]

As above, what method did you use to 'test' the pump?

IF you simply turned the key to the on position and was expecting it to come on and 'pre-prime', it won't. The pump will not engage until the engine is cranking.

 

[SteveH]

@powersculver

First, I would disconnect all factory wiring and bench test the pump itself (just the pump motor assembly) with an independent power supply.

I have a 2000 LC FSM, and the polarity for the fuel pump wires shown in the FSM is backwards from reality.

Were you required to use crimp terminals for your new fuel pump? If so, did it not plug in directly to the OEM harness?

 

[powersculver]

@powersculver

First, I would disconnect all factory wiring and bench test the pump itself (just the pump motor assembly) with an independent power supply.

I have a 2000 LC FSM, and the polarity for the fuel pump wires shown in the FSM is backwards from reality.

Were you required to use crimp terminals for your new fuel pump? If so, did it not plug in directly to the OEM harness?

It did not plug directly into oem, aftermarket part required harness switch

How did you test the fuel pump? Did you turn and hold the key and let the engine cranks?

Yes, pump won’t come on while cranking from what I can hear

 

[kevgentile]

What @SteveH said is correct. The black and red wires for the pos and neg got me too when diag'ing my pump and pump ecu.

If you have the correct polarity then you'll need to go back to the fuel pump ecu in the left rear and meter the circuit. There's plenty of how-to's and voltage/ohm specs regarding the pump ecu in the workshop manual.

 

[powersculver]

Update - Fuel pump is coming on, getting gas to the filter but the truck still won’t turn on. What else could be causing this problem? Clogged filter? It was driving fine and then got back in it after 10 minutes letting it sit and stalled out while taking off and now won’t turn back on.

 

[Trunk Monkey]

When you say won't turn on you mean it won't crank over (starter) or will crank but won't run? Immobilizer light turning off or blinking?

 

[powersculver]

When you say won't turn on you mean it won't crank over (starter) or will crank but won't run? Immobilizer light turning off or blinking?

It will crank but not run, immobilizer light is not on. Pulled hose with green clip off of filter and fuel is coming through that hose when you crank.

 

[medtro]

Pulled hose with green clip off of filter and fuel is coming through that hose when you crank.

Fuel come out of the line when you crank doesn't mean it is good enough for starting. You may not have the appropriate fuel pressure to get the engine started.