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i just purchased this truck about 4 weeks ago i have a 3406 c 3zj43112 arg # 6I1733 15-17 manifold psi is all i can build up. I have replaced fuel lines from primary filter to transfer pump to second filter and then to pump. also replaced transfer pump got 40 pounds fuel psi.
checked the air to air it will hold 17 psi for around 5 minutes no leaks i sprayed the air charger with soapy water no bubbles. replaced 4 air boots no leaks. had a cat man rebuild my timing advance and inspect my governor housing. at around 1230 rpms it starts building he set at 16 degrees. the truck smokes pretty good from a start but you have to stay in it to reach 70 mph also has what i call trashy smoke coming out of stack pryo stays around 81/2 water temp does try to climb slightly. when it starts out it seems to do ok until the boost hits 15-17 then thats the end of the story. i have checked the diaphragm and replaced it it was fine , my nozzles are suppose be 2or5169 i just found out this engine could have 16:4 or 15:2 compression pistons not sure what i have yet truck runs smooth just does not have that clack you normally here with one with a little fuel to it. i also took around out of each screw no change. had a spare turbo changed it no difference the turbo on it is a 7w9568 it should have been a or6689 from what i was told it is fine i have a 6nz turbo to install but going to have to make a few modifications to install. any help would be appreciated
 

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Ok, asked around.
RZ says;
What is the HP rating and does the truck have acceptable performance? I've seen 400 HP B's that only ran 20-22Lbs of boost under a full load and that was normal for them. Also, is he trying to run 1900-2000 rpms? I've seen 425 HP B's that would not boost until they got lugged down to 15-1600 to get some manifold heat going. Don't know if that was right or wrong... but it was 5 identical trucks. And what is the water temp. Some of those were happier powerwise at 195 than they were at 180. Just some thoughts. It may be more operating conditions than an engine issue.

Oh... check the boost gauge for accuracy and the tubing for holes, seen that one too.

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Ken says,
That pressure is low should have at least 70 psi, check the filter housing and primer pump. Did he check pressure at filter housing? That is a early C model with a 3ZJ#.
 

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RZ came back and said
Yep, it's the fuel pressure.
And who is Ken? Durn autocorrect, should say TS. Site won't let me edit neither.

TS continues;
The fuel flows through the primer pump, if the check valve partially rolled it will cut the fuel back.
If it turns over completely it can shut fuel off. I know this because I've had it happen right after priming the system.

Personally I wouldn't go swapping turbos around because each turbo is matched to engine parameters. The only way you know what it's doing is on the dyno.
 

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40 is adequate fuel psi. especially under load. I have a FASS pump feeding my tranfer pump and I don't think it will hit 70 with no load.Originally, I think those were the stock numbers for my nozzles and turbo. Timing at 16 degrees is pretty close - maybe just a fuzz faster (maybe a degree? ) My 425 ran about 18psi stock and would barely tach 2K and quit pulling at about 1900. Got about 5.1 mpg and got passed by Schneider coe binders in the hills. Changed governor to purple spring and a couple or 3 rounds out on screws peaked boost for that turbo at about 28 or 29psi and pulled hard well past 2100. Pulled 8+ a little on pyro and got about 6mpg driven sensibly pulling a van or reefer. I agree with the check guage and related.
 
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