general fuel / pump question

[jethro]

Wanted to ask about this thing I noticed as I was hoping for good MPG's (eventually)
When my motor was running on the engine stand- I had done very little to the fuel system. All the injector tips were bad, was running the old rubber diaphragm fuel pump- injection pump was stock (I think) - still I thought it ran OK (smooth)
I had the fuel pump drawing out of a gallon paint can with about 3 inches of fuel in the bottom. I noticed I could let it idle
for a couple hours and not really see much of that fuel missing from the can. Couldn't have been more than 2 qts. Also I could
see a little trickle of fuel coming back to the can through the fuel return line.

Fast forward--- new injector tips, IP overhauled for new O-Rings. New head gasket. New 60Lb+ valve springs, new chr-mo
push rods, new head gasket, new crank oil seals, KDP, New 2-nd gen piston fuel pump with 12 lb spring, Overhaul shop said they turned pump up a little (they said 20%) , new manifold, using old turbo H1C with new center seals.
After all that work - now I see no more fuel coming out of the return line. The motor is in the truck now- I am suspicious that
it could be using too much fuel compared to what I wanted....... don't see any smoke except for a little at first start up.
Don't have a pyro on it yet... or water temp ...... or boost...... those are next on the list.

What does it indicate that no fuel returns to tank ? (should I check oil just in case volume increasing ????)
Could it just be turned up too much ? Seems to have plenty of power when I drive it round the yard- (93 intercooled
engine in a 2004 ford 350 ) No black smoke anytime so far.....

Thoughts ?
Tim

[PToombs]

Did you mean no fuel, or no more than before? Return fuel from the injectors is seepage , meaning they are worn and letting fluid bypass internally. Redone injectors shouldn't return hardly at all. As for the IP, I would think that should return fuel on a constant basis, but I can't say how much. Plus, you will have more return at higher RPMs because you are pushing more fuel in the system.

After you start driving it see what you get for mileage, then you can worry about if you are using too much. What little you have run (idling and driving around the yard), it shows nothing about how much fuel it will use in the real world.

[jethro]

I guess the "look" of the change worried me. Before it has a good little speen of return fuel. Now - none.
I had been just putting 2 or 3 gallons of fuel in the tank (40+gallons ?) I was noticing I could see the level go down
pretty fast without much running. But too- the sender arm is about at 60-70 degrees when near empty so maybe that is
kind of amplifying the "look" of the gas needle dropping. I have more in it now. I put in 10 gallons and it came upi to between 1/4 and 1/2. Must hold a LOT of fuel.
I am about to put LT235-85-r16 tires on so I hope they will encourage good mileage compared to the balloons on there now.

Thanks for the thoughts !
Tim
Have to post some pics of it if I can remember how .....