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Lift pump function

SnowDrift

SnowDrift

Ultra Conservative. ULTRA!
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I've removed the lift pump relay, thinking it would not allow the pump to run, but after cranking a while, the lift pump begins to run (in a no-start situation). Does this sound right?
 
The lift pump gets power from the Ops when oil pressure comes up after cranking for a bit.
My tahoe had a defective lift pump relay when I got it and the pump would still run when the engine was running.
 
On my 97, if the relay is removed, the lp will not run a few seconds after shutdown. Thats all I noticed
 
On this one the relay hasn't been in since I started working on it in order to keep it from running, intentionally. I disconnected at the frame connection, so it's off, now, but I thought it wouldn't run without the relay.
 
SnowDrift, a better way to accomplish this would be to disconnect the fuel shut off solenoid. A healthy IP will draw fuel from the tank without the lift pump, but it's going to put more load on the transfer pump vanes so this isn't recommended. Let the lift pump run because it will keep your IP lubricated with fuel. Also be mindful that you don't overheat your starter - the windings short partially and they start to turn too slow to start the truck reliably, and increase current draw.


Sent from my iPhone using Tapatalk
 
Mechanical IP - internal to the pump. Terminal is on top, passenger's side of the fuel return, if I'm not mistaken. Electronic IP - round can sticking straight up on the driver's side front of the pump. There's a connector not far from the solenoid.

Best 'o' luck!
 
Thanks. Not a bad idea. If I pull fuel from the tank, then I'll do this. Right now, my fuel source is sitting on the fender.
 
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