Hey everyone, I have a 93’ first gen dually with a second gen manual nv5600. Used to when I drove it and would build boost before I change a gear and get high in rpm before letting off gas pedal the turbo would make a large whistle noise almost like a blow off. Loved the noise. Anyways I swapped ve pumps and this pump is virtually stock except the 3200 spring. Now i don’t have the turbo noise when letting off the gas. The only thing i can think of is the AFC line on the ve I broke and replaced it with an air fitting 5/32” for now until i get the braided one. Is this what’s causing this or something else ?

thanks!

 

Swapping one VE pump with another one and expecting the engine to run the same, is not reality.

I usually spend MANY hours tuning a pump to run like I want, and if I have to change the pump years later. I have to start again.

Do you have gauges?
At what boost is it it compared to before? At 1/2 throttle? at full throttle? At 2000 RPM? At 2500 RPM?

What Pyro # are you hitting on the same grades, in the same gear, with the same load?

You will need to do test and tune runs as I call them. I literally bring tools and pull over in parking lots and adjust things when I am trying to get my motor to run how I want it to.

There is no standard setting that works on all VE pumps, They need to be individually tuned and adjusted.
Some VE motor I find like a aftermarket fuel pin. Others run too smokey / hot and I find a OEM pin turned to the deep side works better.

What is your idle RPM?
What is max RPM?
What was it with the old pump?

Have you turned the fuel screw?
Did you adjust the last pumps fuel screw?

Do they both have the same tension AFC spring?

Have you tried adjusting the star wheel?

Is the throttle rod adjusted so there is no slop?
Does it move with just the slightest depression on the pedal from the cab?

Is the smoke screw adjusted the same as the last pump?

Who know how your knock off Bosch pump is set from the "factory".
I have swapped in 100% OEM stock, with tamper proof caps and paint dabs in place, VE pumps and needed to adjust things differently.

You will need to do some work under the hood to get it to run as it did before.
If you do not have gauges yet, now is the time to install some. It will help with tuning the pump quite a bit.

It would be like getting a new girlfriend and saying "When I do the same thing I have been doing for years, I get a new reaction...Why?"
You made a major change. Major changes, make things majorly different.

 

No I don’t have gauges, it’s on the list. I have only adjusted low idle screw and full throttle screw, nothing else. The other pump still had tamper cover on these screws but uncertain about fuel/power screw I’ll have to check.
The pump works great so far zero issues, I would think DAP would sell decent pumps.

From what I understand nothing on this pump other than the AFC could cause loss or gain in that sound ? I did see one time here someone calling the smoke screw a “boost screw “.

 

You can do some tuning without gages. YouTube is your friend look up first genhub. He shows how to do basic tuning.

 

I am not saying it is or isn't a decent pump, as I do not know.

I AM saying it is a DIFFERENT pump made by a different company 30 years later.

You asked what else could be the reason why your truck is different now.
I took a decent amount of time to make you a list of thing to check.

 

Like the twins I dated in high school, they may look alike, but that is where the similarities ended. Without gauges, you don't have a base line to reference. I suggest you get them before tweaking blind, and record everything you do. I have been happy with everything I've gotten from DAP over the years and customer service has been excellent.

 

Maybe you should swap the gas pedal for a diesel pedal?

Sorry, couldn't resist... I'll go back to my hole now...

 

I’ll definitely be getting some this year, after all I have a 351 turbo from a third gen and want to throw on new injectors so like you guys say I need the gauges. I’ll sit on this until i tune pump and get gauges.

thanks everyone !

 

You might be surprised what you can do with what you have. Without a hotrod fuel pin the techniques are the same.

 

thanks, I’ll do the Star wheel and power screw adjustment per his instructions. I know stock it can do well but I’d like to put the new third gen turbo on with new sticks to see how much I could get out of her, after all turbo is basically free from a bud who upgraded. I have a lonnngg list of things to do to the truck cosmetically and performance excited for all of it.

 

If you haven't done this, Get a HVLP piston style Gen2 fuel pump.