Little-bit

I checked my lift pump PSI yesterday. When you turn the key on the lift pump psi comes up to about 2 psi. The psi would go to zero as soon as the pump would cut off. Is this normal? Also when the truck is running 0-2K rpm's the lift pump is putting out around 10 psi. What should this pressure be and is 10psi OK? Thanks in advance.

tchdodg

I had to do the lift pump/injector pump replacement about 6 months ago in my 2000. Currently, it runs about 15-16 psi at idle. Running down the road at 70mph/2000rpm it still holds about 14. I'm relatively new to the diesel world, but from my experience, I'd check the lift pump, before the injector pump goes too. Just my thoughts.

Little-bit

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Ph4tty

Yes the pump just runs for a 1/2 second before you turn the key. Then pressure will build as soon as the motor turns over. 10 psi is fine.

My fuel pressure is simular to tchdodg using the fuel line kit from vulcan performance. Expect more of a drop in pressure with the stock banjo bolts than what I'm seeing. 0 pressure = very bad and opinions vary on how little pressure is acceptable for cooling the IP. If mine got anywhere close to five I'd be ordering parts.

Little-bit

Thanks for information. I'm glad to hear that 10 psi is OK. I would have thought that the LP would maintain the initial make-up pressure before turning the key to the start position. I was surprised to see it bleed back off.

CORed

I have run the stock LP in the stock location and a P4601 Carter replacement on the frame. Both would hit almost 10psi for the second they run before starting and both bled off pretty quickly to zero before I started the truck.

I'd probably agree that 10psi is OK, but if normal cruise is closer to 5, I'd be replacing it too. Your goal should be 14+. That is supposedly the psi that the internal VP44 bypass opens which allows more fuel to flow thru the VP44, thereby cooling it better... assuming, of course, your fuel is cooler than 180* (it should be)

I run about 13psi tho and don't worry about it too much until my pump dies.

high country

it is totally normal for your pump to quit before you start your truck, the truck will not start easily with too much fp before it is running, after running it should pick up and never get below what ever you decide is your safe limit, everyone has a different opinion on what too little and too much are.