Hello fella's. Hav'nt been on here in a while, hope everyone's surviving these record high temps through out the country!

I'v been having an issue lately. The truck has lost a bunch of power, boost is very low and and theres more black smoke than usual. The max boost rite now is 15psi, and its fairly hard to get to. When climbing a hill I drive every day if its at 5 psi and I give it heavy throttle it gets to 12psi and stays, then starts black smoking like its being lugged heavy.. I just shift down and creep the rest of the way. Anyway it has lost a lot of power, like the turbo is'nt spooling like it should, or over fueling and smothering the turbo. If I cut the air to the AFC and makes little or no difference, I usually drive with the AFC shut off anyway.


First thing I checked was the air filter, I changed it and it did not help. While I was at it I spun the compressor by hand and it feels good as new. I pressurized the intercooler and it seemes to hold air well at 20psi. Checked and adjusted the valves, still no change. Fuel pressure rarely drops below 5psi when driving normal.

Any other ideas? Im at a loss... Thanks in advance

 

Check the little fuel pin that pushes on the afc aneroid cone and make sure its not stuck inward. Easiest way to check is to pull the co.e and diaphram out and move the throttle. See if it is stuck in or out or moves as all. It should move out when throttle is applird amd you should br able to move it in freely when at idle

 

Ok, I'v been told this by someone else. The fuel cone will not by any means come out even while turning it, by applying full throttle, applying the shut down lever or anything. It moves up and down freely but just will not come out. So I'd say you're probably rite that the little rod that goes against the cone(pin) might be stuck.

Time to pull the top off the pump I guess. Thank you for the opinion. The only thing to be carefull of is to take the full power screw out and keep an eye on the "top hat" and spring correct?

 

You can leave the power screw where its at. And just use string or wire to pull the power lever when you put the top back on. And yes keep and eye on the top hat and spring.

 

Just for a test I turned the smoke screw all the way in and drove the truck. I could'nt see any more smoke than usual so the that pin is most likely stuck. I tell you what, I really dread taking the stinkin' pump top off..

I thought of another couple possibility's to look at first. The W/M injector tubing, and the boost reference tube that goes to the W/M controller.

 

Just another thought, do you have a manual kill cable hooked up? I had mine bind up once and it was enough forward that the truck would crank and run but had no power. Barely made boost and no smoke either.

 

I don't have a manual kill cable hooked up, I just went and checked the kill lever and it seems fine. Worth lookin at though.

I plugged the W/M injector hole in the intake and no difference.

I did find a possible leak.


I started noticing a slight hiss in the engine bay when the turbo would spool up. today I found that the intake plate gasket has worked its way out in a couple spots.

1-Should i just put a new OEM Felpro gasket in? Or is there a better choice?

2-Would putting gasket sealant of some sort on a new OEM paper
gasket prevent this from happening again?

3-Could water/methanol cause problems with the intake plate gasket?

 

You might want to check this little metal line on the injection pump I think its connected to the diaphram the other were talking about. My was broke but still looked to be attached. I ended up replacing it with air brake line and fittings. I will try to get a picture later.

 

I looked at the AFC boost line, seemed ok. I also had a nylon line ran into the cab with a valve but I put the steel line back on and theres no change.

 

I purchased a new intake plate gasket (Felpro). I'll install it and see if that helps.

Then I also purchased a VE re-seal kit and 3200 spring. I figure if I open the pump top to un-stick the fuel pin, might as well do the spring while I'm in there so I don't have to open it again.

 

I got the pump opened up, the slide pin was not stuck. It moved in and out with the cone pin. The cone pin still will not come out though.

I might have fixed the low power and smoke issue, there were several large rips in the intake manifold plate gasket. Its funny that it just recently started making an audible hiss when boost builds, as big as the rips are it should have been hissing like crazy when the low power problem first started.

I'll drive the truck for a few days with the new intake gasket and report back with the outcome.

 

Boost is still max 15psi +/- and the low end power is slightly lower than before (dont seem to fuel as hard), although the truck smokes slightly less and mid rpm to max range is slightly better.

 

sounds like a timing problem to me. If it's not advancing the fuel would get put in to late to make power or heat to spool the turbo at higher RPM. I don't know enough about these pumps to give much more insight than that though.

 

As far as timing goes, If I put it rite at the stock line the low end power is slightly better but EGT's are pretty high and top end power suffers. A 1/8" bump drops low end power and it does gain a slight bit of power up into the rpm's, and the EGT's are slightly better. I set it at 1/16".

Today when I got the truck to 50mph I give it almost full throttle and it got up to about 14psi of boost and down to 4psi fuel pressure in 5th gear. Egt's got to about 1200-1250*f until the turbo caught up, then down to 900-950*f when it got to 70mph. I may have let up on the throttle some, ti will get up to 1300*f. Still feels like 40hp less than before whatever got messed up.

Cruising at 65mph, 6psi boost and EGT's at 500-700*f

Acceleration 50-70mph was equivalent to that of a '98 chevy Z71 5.7 auto without revving past 2000rpm (grandpa driving).

Im lost

 

Have you tried a spray bottle with soapy water mixture to check for intercooler leaks? Just a possibility...