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Discussion Starter · #1 ·
12 valve uses a diaphragm driven off the cam. Pinnacle of reliability and simplicity

24 valve vp44 engine uses a centrifugal vane type pump mounted ABOVE the tank on the block, and is controlled by a wear item relay INSIDE the cpu where you can't replace it???

Is this as dumb as it looks to me, or am I missing something?
 

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Well, I don't think you missed anything, this is why the FASS and Airdog systems are so popular...
 

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Yeah get a fass hpfp i love it, it is alittle noisy though but now I got the rhino liner I can bearly hear it
 

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12 valve uses a diaphragm driven off the cam. Pinnacle of reliability and simplicity
Actually, the 12 valve lift pump does NOT have a diaphragm. It uses a piston which is much more reliable than a diaphragm.
 

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Discussion Starter · #5 · (Edited)
Dang, that means, the way I understand it, the lift pump kicks on dry, throws the vanes out to prime pumping dry, metal on metal, and is controlled by a wear prone relay in the pcm which means this setup absolutely NEEDS to be changed on ALL trucks as it can take out you PCM as well as your vp44.

I was running a carter on the framerail powered by a relay with the signal off the factory pump, and disconnected the aulillary while I was waiting for a Hobbs switch to kick the aux on at 4psi (stupid setup by the way) and found that my BRAND NEW lift pump wasn't kicking on. None of the fuel relays control the lift pump.

So this means my relay in my PCM has worn/corroded contacts, and was not kicking on randomly and my aux was runnning the whole thing. :(

I rewired it to have the factory plug run a relay which carries the load for BOTH pumps now, and no problems. I guess the higher motor load was too much for the constacts.

Interestingly enough, I dug out my goodies that came with my carter pump ($90 and same as my factory pump except for npt fittings and posts for the power) and found that it came with a FACTORY STYLE male and female plug. So I was able to make a new harness on the bench. Plug and play. No splicing on the truck.

All you need to do it this way, is an inline fuse (12 ga and 30 amp), a bigger relay just like in the fuse box (they are good for 40 amp), a carter pump, some connectors, and a couple pieces of 3/8" fuel line. Works the same way as a FASS, just won't exceed 10psi and no second ff.
 
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