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ssybert
04-22-2004, 21:33
Hello everyone...

I added some components to allow my truck to run on used vegetable oil (if you're not familiar, it's not important) and in the process, I had to add an additional lisft pump for the veg oil. People recommended a HOlley Blue but it just plain did not work. It's vein style pump and is NOT strong enough to pull it through the lines. I recently purchased a new pump... It does about 1.8GPM @ a max of 50PSI. My question is, even though the fuel pressure is MAX 50, as long as the return line from the fuel injector pump has some place to go, will the high PSI make a difference? will it even build that kind of pressure @ 1.8GPM?

Another question would be, is the return line of the IP passive so to speak so you could pump RIGHT THROUGH IT and the IP would take what it needs from fuel as it flows THROUGH it?

I hope I explained this clearly enough, It's late, I need sleep but still need to know the answers to this critical question(s) before I put this pump in Saturday.

Thanks, Scott.

AndyL
04-23-2004, 03:02
The IP bypass is not passive. That is how many 6.5s will still run when the lift pump goes bad, it is pulling fuel from the tank.

Since Veggi oil doesn't foam like Diesel I would say 50 PSI would be OK at the IP. Just a guess.

ssybert
04-23-2004, 10:47
ok great. I wasn't sure if there was a risk of blowing seals or anything. Those god damn pumps so expensive I didn't want to find out the hard way. I'll post my results after the weekend. Wish me luck! tongue.gif

tom.mcinerney
04-23-2004, 17:28
Scott--
Be advised that '94-2000 6.5L LiftPump output pressure specified 4-8psi. I believe earlier 6.5 and 6.2 OK with input pressure 4-15psi. The later 6.5L LP designed with integral pressure-regulator, more expensive than earlier , unregulated LP.
Suggest press-reg before FIP.
Also, consider that:
Liquid viscosity limits pump capability. Viscosity is usually dependent on temperature of fluid in question. Results vary if a pump is installed near the line's input or its output.
Suggest type "npsh" into Google; follow the first few of the 17K links that appear!