• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

Low boost despite upgrades.

Nessmuk

Nessmuk

Well-Known Member
Messages
432
Reaction score
276
Location
East Amazonian polar region
Alright, I'm running an hx40 turbo, moose junior pump, marine injectors. The exhaust is all recently new, just put a new intake gasket in. The pump seems to be timed right. Fuel pressure stays above 5 psi. Good clean air filter. Boost is hard put to see above 10 psi. The waste gate is closed.
I'd like to see 15 or more psi as I studded the optimizer block for it. Plus I'd like the wmi to kick in at 10 or more psi.
What thoughts?
 
Yup, low end is only thing making me wonder. Hx40 is wonderful top end, getting it lit can be an issue. But that pump can help there.

What about your injectors? I know marine- What pressure popping and did you balance them?

Anything else done on balancing, lightening, etc?
 
I'm wondering if there is any possibility of a plugged return line affecting fuel output to the injectors. Doesn't really seem like it could but ....
 
The injectors are new. All the fuel lines are new also. It only makes a haze if I get into the pedal. It's been about 10 psi no matter what I do. I'm going to put a cap and shrader valve on the turbo and spray soapy water next.
 
I don't know how you have your WMI set up. My controller is set up to come on at 5psi. Unfortunately it's not really adjustable. Snow's lower budget kit actually has the longer I like instead of the electronic digital display I have. It's fully adjustable start and stop points. I put it on my friends 7.3L Super Duty and with that controller we were able to get it tuned in amazing. WAY more adjust ability than the system I got. Maybe something to look into if you don't have it
 
I bought a boost switch that screws direct into the intake and is adjustable from 5 psi and up. I was just shooting for over 10 psi as I only want it on when I really need the power. There is also a valve that connects to the switch and opens when it gets power. That valve is in the water hose to keep the boost in until the pump comes on. I've never even used any of it yet.
 
It will definitely help. This is a video I made showing my exhaust manifolds difference, but I compare it with WMI ON and OFF and you can really tell the difference.

 
You either aren't throwing as much fuel as you think you are or you are gating the turbo and loosing the drive pressure...

If you don't have smoke at low rpm's then you don't have excess fuel...

Boost pressure is very dependent on the amount of fuel/heat passing through the turbine....

My guess for what it's worth is the pump isn't throwing as fuel as you think...
 
ak diesel driver said:
I'm wondering if there is any possibility of a plugged return line affecting fuel output to the injectors. Doesn't really seem like it could but ....
Click to expand...

Can't you pinch the return line and shut down the engine?

No smoke means no fuel.

Turbo's likely fine: If it wasn't you would be blacking out the sun rolling coal. Do you have a pressure gauge before the IP? Did you verify the throttle cable will put the pump throttle lever at full rotation? Not the first stretched or maladjusted cable out there...
 
Update. I do have full w.o.t. with the pedal down, and turned back the w.o.t. limit screw untill it just contacts. I'll keep an eye on rpms.
I have / had a boost leak at the wmi line, found I put air pressure to the intake. I did a little r&r and added some Indian head shellac to it, have not rechecked it (it's one of those new fangled whipper snapper alligator push fitting things with clear pex-ish hose).
I also found a leak at the drivers rear injector to look into after it cools.
Plumbed in a manual temp gauge to get a picture of the actual coolant temp.
Unplumbed the steering return from the radiator cooler and it seems maybe a bit smoother.
Drilled vents into the fuel caps.
What way is there to confirm that the fuel return is unplugged?
 
Remove fuel cap. use a piece of hose hooked to the return line (post injectors) and apply 3 psi air and it should push into the tank. You should hear bubbling in the tank.

You should not have to have a vented fuel cap. Infact anywhere diesel smog is required that is illegal. If you are in a high humidity area that is a bad thing as it will allow moisture(water) to increase in the tank. I didn't realize you were going to drill the cap(s) or I would have said not to.

The tank should vent through the tank vent. A hose coming out of the roll over vent valve. From there some rigs have a small filter, others are just open to air. If you ever suspect bad vent valve, just a quick test drive with out a cap for diagnosing. Usually the problem is the tank get sucked in and collapses on itself, or not enough fuel so lack of power on freeway & no smoke, maybe hard starts.

You can also run the return lines into a jerrycan beside or in rear of truck, just keep the line submerged in fuel. If that clears it up, that tells yo there is a restriction.

Too bad Leroy (@Burning oil ) doesn't rent a db2 timing tool like he does the oil primer. knowing you are timed correctly is not a bad thing to eliminate it from diagnostics. Doubt it is your problem, but it can mess with it.

What is the pop pressure on your injectors? Higher pop pressures restrict volume but mists better.
 
Looking at things, it's not super far off. Your pump is rated for about 90cc's. My 4911 was at 88cc's and with my billet HX40 60/64/14, it spools about right to 20psi, but but a larger 16 or 18cm exhaust housing and tiny compressor wheel like the HX40WII, it's not far from what I'd expect from that turbo with that fueling. Hit it with the WMI and see where it gets.
 
I don't understand. Do I buy that?
I think your saying a smaller exhaust housing? I see whole hx35 turbos for under 200. Would that be a drop in?
 
Last edited:
You must log in or register to reply here.
Back
Top