I tried turning up the pump on my cousins 6.9 but couldn't get the allen screw to move more than about 1/8 of a turn. Is it possible it could be maxed out? As far as we know it's never been turned up, no real smoke to speak of coming from the exhaust. Injectors were replaced about 2k ago

 

Here is a post by Ken........

The reason for not bottoming out the screw is -
When you turn the screw in you're increase the piston travel length in the pump (inside the charging chamber) Good thing? Yes, more fuel. BUT, if you turn that bugger in too far, (bottom it out) the pistons will actually have too long of a travel, and as soon as you go to WOT, they'll start to compress the fuel before the discharge ports line up with charging chamber. In a nutshell, instant hydrolock. The input shaft for the pump will shear clean off.

Don't want to scare anyone, I've just seen it happen (many times, unfortunately). Most recently was a kid at a county fair tractor pull. They hooked the tractor to the sled, he took the slack out, slowly let out the clutch and increased the throttle. As soon as he reached full fuel, the tractor instantly died. He tried to start it again, and had no smoke from the exhaust. Talking to him after the pull, I found out that he had just learned how to turn the pump up from a local shop, but they didn't tell him not to go too far with the screw. "So I thought that if you turned the screw in all the way, then that would be the maximum setting for the pump" I guess he found out the hard way.

I told him next time he wants to pull, let me know. "We've got a few ways to get a lot more fuel out of these pumps than you can by just turning that screw in."

Ken

 

Out of curiosity, what would these other ways of getting more fuel be? Not that I'll ever use them, I'd like to see some smoke out the stack but unfortunately my experience has been that 20mpg and black smoke just don't like to coexist, but still I think it'll be interesting to know what else can be done to drown the engine in fuel

 

Wouldn't it be smoking something fierce when the screw is close to being maxed out? And a loss of power due to too much fuel? Could anything have gotten in there to bung the threads to where it won't go any further? Or possibly the pump getting weak?
I talked to him today and it's got a small cloud on heavy acc and shifts (4 spd) lil more power but not a huge amount. EGT's didn't seem to change any either.

 

DPS Performance can get over 4 times the amount of fuel out of an IP as you can stock.

If the IP on the 6.9 is original equipment, it is probably very tired and so would the injectors be if they are original.