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Discussion Starter #1
Used to have an account here but haven't used it in a while and now i can't get into it so i made another.

Heres the deal:

I have a 93 12v, nv4500,hx35 and 350 000km. The truck had great power before i worked on it.
So i parked the truck for 3 months while i did a cab and deck swap. I also put in a 3200 gov spring, 60lbs exhaust springs and an exhaust brake.
My truck used to blow a little bit of black smoke and now it doesn't smoke at all. It has no power in 4th or 5th and cant make it up a small hill unless in 3rd. It runs and drives great, fires up right away and i can cruse around and do 120kmh but if i hit hills im going to 3rd.
I have 6.5psi fuel pressure. It wont go above 15psi boost and it wont get hotter then 700 F post turbo when im pushing it to its max.
I have tried re indexing throttle, re adjusting full load adjustment screw and afc adjustments.

Im completely stumped and am now in a rush because I have to drive through the mountains in a couple days.

If anyone has any input throw it at me please.
 

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Maybe you got some moisture in the fuel tank from sitting and the fuel filter is plugged up.
 

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Best guess is your fuel slide pin is stuck. That is around the maximum PSI you will see if the pin is not moving.
What fuel pin do you have?
Cheers Steve
 

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Discussion Starter #4
I emptiedthe tank, cleaned and vacuumed it out. Been running new fuel for the past month. The fuel slide pin had some rust looking coloration so i have filled that hole with liquid wrench and worked it a bunch of times. My fuel pin looks stock and is as far as i known and is set to the deepest setting.
 

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Is the small slide pin at the bottom of the AFC that rides on the fuel pin free? It could be gummed up if there was crud in the bottom of the fuel pin hole.
 

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Discussion Starter #6
I cleaned the fuel pin hole and worked the fuel pin alot to insure its operating.
I installed the original gov spring and it didn't change anything.
I have a friend thats dead set on it being the afc diaphragm causing a boost leak but he won't be here until tomorrow with parts to check that theory.
 

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I cleaned the fuel pin hole and worked the fuel pin alot to insure its operating.
I installed the original gov spring and it didn't change anything.
I have a friend thats dead set on it being the afc diaphragm causing a boost leak but he won't be here until tomorrow with parts to check that theory.
If you pull the fuel pin out and open the throttle all the way (engine off) does the little slide pin that rides on the fuel pin pop out? My bet is no and that is exactly your problem.
 

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Do what myother said.
 

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When you say cleaned it plenty did you pull the pin out when you had the top off for the governor spring change? That is, knock the retainer balls out and remove the pivot pin and then the slide pin? Did you replace the slide pin O ring?
Easy enough to check the diaphragm operation, hook the pin out and clean it well and use a permanent marker and coat the pin, replace and run it the pull the pin again. You will see where the slide pin has been running on the fuel pin.
 

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When you changed the governor spring did you back the fuel screw right out?
 

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Discussion Starter #13
Yes i backed tge fuel screw out an then lost its original position. So i found where the thread locker was on the screw and set it there.
I have adjusted and re adjusted it a few times now, i found where the rpm hangs and backed it off a half turn.

I also installed a magnaflow muffler and fixed exhaust. Could there be to much exhaust restriction? Would that cause my truck to be this gutless?
 

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When the truck has sat for a while does it start right up on the first crank of the starter? Have you checked to see if your sucking air into the fuel system?

Does your fuel pressure stay at 6.5 psi when your having the problem?

Is your muffler a open center muffler?

Have you put some grease on the fuel pin where the small slide pin travels on it to see if it makes a line in the grease when your at full boost pressure?
 

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Discussion Starter #16
I have a back pressure guage so you think if the muffler was causing restrictions I would see something but it doesn't move unless using exhaust brake.

Upon further investigation I believe I have a hole or two minimum in my intercooler boots. It's funny how you can Overlook some of the simplest things and think the problem could be more complicated than it actually is. Once I get new boots I will update
 

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Discussion Starter #17
I made a tool to pressurize my Boost system to check for leaks and there were none. I'm out of ideas so I'm starting to think that the ve pump is on its way out. I'm going to swap the pump tonight.
 

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We gave you ideas but you never replied to some of them, if you don't want our help that's fine.
 

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Discussion Starter #19
I appreciate your help. I have all new fuel lines, lift pump and i removed the in tank screen when i cleaned the tank. I put a new fuel filter on yesterday and my fuel pressure stays at 6.5psi except when im giving er on the throttle it starts to drop.

I didn't remove the slide pin but removed the top of the pump and worked both sides well with oil. There is recent wear on the fuel.

I have to leave tomorrow morning with the truck. I have been working on this for a few weeks but have now ran out of time and am swapping pumps. I wish i had thought about posting here earlier but oh well. When i get back i willfind out whats wrong with the old pump.
 

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My situation sounds similar to Roadx situation in the 92 low power no boost thread.
I will keep you informed of what I'm doing and the results I get. I will be replacing the fuel pin next with a DennyT stage #1 fuel pin.
I will be out of town for a few weeks but hope to get the pin by the end of week so I can test it before I leave.
 
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