1320

Long story: I bought a pump a few years ago that was supposed to be "worked on" it looked pretty clean, especially inside , seals etc. Plus it was priced OK. Fast forward, my truck has been smoking, light load empty or 65 mph with the trailers. The pump on my truck was original, about 300k miles. It would pull good, power to 3600-4000, 60 psi boost. And lately last year mpg was down.

So I thought maybe the miles, were causing low pressure and poor fuel control and therefore smoke and low mpg return. ( run DDP 4 ink and 10 plate about 3/4 forward. )
The replacement pump is the same number. I swapped my 4000 gsk. Installed the pump straight up. (I HAD lift timed my previous pump to around 16.5/17 I think, did it years ago).
Hoping for a change, I got it! No smoke....some white , but it acts like no fuel. It runs nice, pulls from pretty much idle, probably builds 10 psi by 1500(twins) and the party is over by 2600. It'll go higher, just no power. The eggs are unbelievable low! Like 800 driving it hard . old pump would see 1100 empty, (like racing a corvette) I'd hold 1250 on hills at 35/40 psi at 68-70 mpg towing 20k ,5th gear). I have not towed with the new pump.
boost is way down, only see 40 psi when I load it in 4th or 5th gear hard. Empty I see 28-35 psi before the power falls off and time to shift.

is all this due to pump timing? I suspect the timing is really really low, like I put it in at 0 and this pump may not even have the industry standard of 13.5 built in. The power falling off and low egts are my indicators, along with low boost.

Can timing effect it so drastically? I turned up the AFC almost a the way, slid the 10 plate all the way forward and the AFC housing too. The star shell is almost all the way counter(lose) I should be getting tons of fuel, but I don't think I'm getting full rack travel? Maybe?

Pump and tuning experts please chime in. My trucks been so good I new this stuff 10 years ago, then I be just been driving it.
My next move with guidance I suspect will be pop the gear off and advance the crank 5/8s , maybe more eventually, but I don't think a dial indicator will do much good if I don't know the pump history.
And yes its studded, camed, ceramic coated, 020 over, ported head, etc....

gorms

I'm guessing you have ruled out fuel supply issues?

What pump do are you currently running? And it's currently pin timed? If it was an industrial pump original timing was something like 11.5° and will not make much power above 2500 rpm.

You may want to re-visit AFC tuning as well.

1320

it is currently pin timed. The number on the pump is exactly the same as my original 98 215 pump.

I did rule out fuel deliver. As i drove it today i wondered if im like one or two clicks lose on the gsk.
I was also going to turn the afc screw out a little as i can get a has just pre boost. It does pop a tiny bit in the exhuast when cold. Very finicky when cold and hard to light off tge turbos. It starts very easy but will idle down and die when cold for about a minute.​​

1320

Update: I finally got around to checking the pump lift with a dial indicator. It was at about 11-12 degrees on the pin. So I moved it up to 5.75 mm or about 17 degrees, but when I checked it, it was closer to 16 @5.45 mm. It's close.
i looked at my barrels and delivery valves. The replacement pump had...179 dv so I swapped in the 181 from my old pump but kept the original barrels. My old barrels looked worn 250+k and the replacement barrels looked pretty good.

So , while I did this, I fixed a vacuum pump oil leak, not the seal, but the housing, so a little gasket sealer and 0$ spent. I also put two crank case breathers on.

I had a AFC housing leak, so a tapped and helicoiled the AFC mounting holes in the pump, then put studs in. Now its sealed, so tuning started over.

Its never run so nice, I might add more on the set screw and star wheel but currently its making good power, no oil leaks, and really no visible smoke. I can get a puff it I lug it a little. There is no perceptible turbo "light off" I think I've covered the lean spot before fuel comes in so the power is very linear. In 13 years of having this truck, this is the nicest its driven. Also the lowest egts I ever seen.

Doing a sound system and a few other things now. The freightliner cab swap has been worth it.