Lift pump shutting off

[tallrancher94]

Howdy everyone,
I am new to the forum, and in need of some help. I have a 2001 2500 HO 6 speed 4x4. Lately, I’ve been plagued by the lift pump shutting off after a few minutes. I shut the truck off (because it was skipping and missing) and bumped the starter to reprime the system, and the lift pump ticked three times like normal but wouldn’t spin. I’ll wait a minute or so, and it’ll pump fuel again. I don’t know what my pressure is, I’ve a wiring issue on the gauge. No, I’m not driving it. I’m at a loss right now. I bought this pickup to pull my stock trailer, but it’s been nothing but a headache. The filter seems to be fine. I changed it a couple months ago. Any ideas? Thanks.

 

[SnoKing]

Lift pump ticked? What is on it for a lift pump? SnoKing

 

[tallrancher94]

Raptor RP100

 

[SnoKing]

First >>> Fix the fuel pressure gauge!!!!!! That will allow you to trouble shoot the lift pump.

NO one should have a 24V without a reliable fuel pressure gauge.

 

[hcole]

Look at this old link. There is a LOT of info on this problem and cure. https://www.turbodieselregister.com/threads/ecm-lift-pump-relay-install.250467/#post-2420249

 

[tallrancher94]

Thanks for the replies. I'll have to give that wiring a try. Yes, I know I should I have a functioning fuel pressure gauge. I haven't been driving it with it not working. Do Raptors normally tick before they start pumping fuel? This one always has, so I've just assumed that's normal. I bought the pickup with it already installed.

 

[JR]

You should hear the lift pump engage for a split second when you turn the ignition on, once the starter is engaged it should run and pump fuel for several seconds.
I agree with SnoKing, get a working fuel pressure gauge to properly diagnose. The Raptors are not the most reliable pumps. Partially because of quality but even more so if it is still mounted on the side of the engine block. If keeping the truck long term you really should consider relocating to the frame rail. The vibration of the engine, heat cycles, and pulling - not pushing - fuel through restrictive (small) OEM fuel lines all contribute to premature failures of any electric pump. Dodge made a retrofit for in tank lift pumps for all 98.5 - 02 trucks.

 

[Joe Mc]

Also note: if you turn key on and LP will run for 5 seconds or so, if you jog key to start (but don't start) LP should run for 30 seconds or so. As others have mentioned a reliable gauge is key. For testing you can temporarily connect a mechanical gauge to be certain of psi.

 

[KATOOM]

This is the normal fuel pump procedure:
Turn key to ON, fuel pump cycles for 2 seconds.
Turn key to ON, bump to START, return to ON, fuel pump cycles for 25 seconds.
Turn key to START, crank engine, fuel pump receives alternating ON/OFF voltage from ECM causing fuel pressure to reduce by approximately half.
Engine running, fuel pump runs 100% of the time.

If the fuel system still has the factory schrader valve test ports on the fuel filter and the VP inlet, then you can buy this https://www.genosgarage.com/product/vulcan-test-kit/fuel-system-accessories-replacement-parts
and check the running fuel pressures from idle to WOT. A dedicated in-cab is best but the test gauge is a great reference tool.

The "clicking" noises, I have no idea. That noise could be a relay or a faulty pump. A video would help with the diagnosis.

Also...its worth knowing that you should NEVER open the fuel system at any time unless you are changing the fuel filter. Because you cause the prime to be lost and introduce air into the system which has to purge its way out. General rule of thumb is to leave all non-leaking fittings and filter housing alone unless they need to be.