I have trolled through several galleries that I thought might have what I need but nothing so far. I have been trying to chase down a low power problem for well over a year now and no luck. I know that sounds crazy, but the truck is not a DD so it sits most of the time. To be honest if it ran like it used to I'd probably drive it all the time but I am so frustrated I am about ready to sell.

Anyway, here is what I need. Next to my VE going south, which it has no symptoms of other than losing power, my problem just about has to be in the throttle linkages. What I need is a picture showing the lever at the top of the AFC sitting at idle, then one at WOT. I posted a few days ago about the size of the high idle screw and Wannadiesel said I did not need one. After looking closely at my setup, but truck does not seem to be getting WOT as what I'd call the "break over" spring on the top does not engauge.

I also found that the 5/16 hex head bolt that holds all the throttle together was a tad loose. Not loose enough to tell by your hand, but I was holding it in place messing with the part of the throttle "tab" that sits on the low idle screw, and while looking at it I found the allen head a little loose. Could my throttle indexing me off from that being a little loose allowing it to be out of adjustment?

 

No, you wouldn't have lost the indexing.

Is your breakover spring broke?

 

Nope, it is a little worn on the side towards the motor, but not broke. I had to put washers underneath my pedal for spacing to take the slack out of the cable and also put a bolt on the open hole right underneath my high idle screw for it to hit up against so the breakover spring can infact break over. When I remove the bolt and hold the pedal to WOT the spring does not breakover. If I make it to where It would break over with the pedal by adjusting the linkage, it does not allow it to go back to the low idle screw.

 

hmmmm, well lack of power over time is almost certainly from decreasing fuel. The IP doesn't 'need' the lift pump for fuel - it'll draw fuel on its own without a lift pump, but if a lift pump was going bad it might make it more difficult for the IP to draw fuel, which might cause lowish power - I don't know for sure, just brainstorming.
My linkage was quite worn, and when I replaced the throttle level arm linkage it got a lot better. Dealer item with fresh ball studs, etc.

Jeff, do you notice your power loss at full throttle or just light duty driving? Have you installed a 366 spring? If not I'd do that first off and see how that affects your power. The 366 spring is by far the cheapest and most beneficial upgrade on Earth. It's in there bud - we'll find yer missing power!

- M2

 

My truck over the past month has slowly gotten weaker and weaker........

I rebuilt the IP not that long ago so I had a good idea it was the lift pump. I had a piston pump in the tool box so I slapped that in and WHAMMO! POWER!!

Now it actaully pulls hard to 3200 just like everyone said it would. Toward the end I couldnt get it past 2200 and that was pushing it......

Might want to give that a look....

Whats your gauge read?

 

Its everywhere as far as the loss goes. I have the 366 spring and installed the new throttle linkages from cummins about a year or so ago - the same time I broke the high idle screw.

I put a piston lift pump on it about 2 years ago and my gauge sits right at 16 PSI - it does bounce a lot between 14 and 16, but I attributed it to being a cheap gauge. The Isspro I had in my sig busted so I bought the cheapo. I do have a snubber and I checked the screeen at the lift pump thinking it might be stopped up.

I drove the truck again today and WOT I only hit about 22 PSI and pulled the Fuel Pressure down to 11 PSI. Last week HAMMERING on it I got 32 PSI and thats it. I know for sure I don't have a boost leak and the fuel pin rides up and down plus the little eccentric pin is also not stuck. I also noticed after I get over 2K RPM's it puffs black smoke - IE its not a steady rolling smoke.

I'm stumped, and I REALLY appreciate everyone's response. Seems it has to be either linkage problems or a dying VE. Like I said in my original post, my breakover spring never breaks over with the way I have it now, which is also the only way it will go back down to the low idle screw for regular idle.

 

You have a linkage problem if you can't get the throttle lever to hit both stop screws. Check the bellcrank bushings for slop.

An easy way to get full travel is to switch the ball stud on the throttle lever to the inner hole. You will have to adjust the throttle rod shorter when you do this.

 

 

Hey Dennis who slapped the piston pump in? I don't remember it going all that smooth, oh yeah and it was raining and dark