Engine/Transmission (1994 - 1998) Afc question

[yenga80]

I adjusted the star wheel yesterday one full revolution towards the engine to increase fueling. I dabbed the wheel with a paint marker to show a point of reference. Didn't notice much power increase so while turning the wheel another revolution today I noticed that the wheel moved on me towards the front of the truck and more out if sight. The spring that is to the right of the star wheel is loose and moves around. Is the star wheel supposed to be more visible under the plug opening? Mine is all the way to the left and I can barely get a screw driver on it. I'm thinking its all the way loose. Thoughts and wisdom appreciated. I tried looking in the buyers guide for info on this but no luck and in the forums.

 

[LNaugle]

hmmm... . who installed the fuel plate?

 

[yenga80]

hmmm... . who installed the fuel plate?

Pevious owner did. Also forgot to mention it appears the the afc is moved more towards the back of the engine. I'll do,some more searching.

 

[Bob4x4]

The star wheel adjust pre boost fueling. Sliding the housing back reduces fueling. Put the star wheel back into the window then start moving the housing forward

 

[yenga80]

What does moving the housing do?

 

[KBurgoyne]

one full revolution is a ton. ten clicks at a time should be noticeable. the AFC controls fueling in relation to boost. moving it forward lets in more fuel with less air so it can build boost quicker. if two revolutions felt like nothing the housing is probably all the way back. dude that put it in probably didnt mark stock location, and the housing has very fine adjustments like 1/16 of an inch. try picking a fixed point and measuring the current location, then move it all the way forward take another measurement, split the difference and set it there. put the wheel back to its original position. with two full revolutions it the truck will send up clouds from every stop. on mine ten clicks was noticeable, 25 was fun, but i lost about a mile per gallon so i set it back.

 

[yenga80]

one full revolution is a ton. ten clicks at a time should be noticeable. the AFC controls fueling in relation to boost. moving it forward lets in more fuel with less air so it can build boost quicker. if two revolutions felt like nothing the housing is probably all the way back. dude that put it in probably didnt mark stock location, and the housing has very fine adjustments like 1/16 of an inch. try picking a fixed point and measuring the current location, then move it all the way forward take another measurement, split the difference and set it there. put the wheel back to its original position. with two full revolutions it the truck will send up clouds from every stop. on mine ten clicks was noticeable, 25 was fun, but i lost about a mile per gallon so i set it back.

Okay thanks for the info KBurgoyne!. I'll try that.

 

[Cosmo]

When I put all my springs and plate in, I set everything more or less stock. It towed my trailer just fine, never got stupid hot on EGTs - only hit 900 degrees a couple of times and there was hardly ever any smoke at all.

After I got home I decided I'd play with it a bit, and I just slammed everything as far forward as possible. It was a noticeable increase in power, and if I get on the throttle at low boost levels it'll lay a decent amount of smoke, but if I don't drive like a jackass it doesn't smoke hardly at all.

Since I was pretty happy with the results, I didn't bother playing with it after the initial adjustment. Picking up a mpg or two would be nice, though. I've been averaging about 15, which with my heavy foot doesn't seem all that horrible.

 

[yenga80]

Well today looked at the afc housing some more and discovered my original post was I correct. I took one of the 8mm bolts out and I know now that the housing is all the way foward to the front of the engine. And I still can't get the star wheel to move for me. Feels like its jammed from when I turned it 2 revolutions toward the engine. The large spring is loose in there. And the star wheel is showing only half of itself in the window. Tried looking in the factory service manual for info on the afc but no luck. I'm to the point where I will have to take off the whole afc housing and see why I can't adjust the star wheel. Also scratching my head as to why the truck won't even smoke at all with the housing all the way foward. Something is just not right with the star wheel.

 

[Bob4x4]

Ok... . step back and stop obsessing over the star wheel. First test your fuel pressure. If it is good pull the housing off and put the star wheel back on its shaft. the # 8 plate is a relatively mild profile. The star wheel is only for pre boost fueling it will not add HP under boost

 

[yenga80]

Ok... . step back and stop obsessing over the star wheel. First test your fuel pressure. If it is good pull the housing off and put the star wheel back on its shaft. the # 8 plate is a relatively mild profile. The star wheel is only for pre boost fueling it will not add HP under boost

Okay I thought about the fuel pressure possibly being low. It seems though I have adequate power. I'll have to get a gauge and check it. Thanks

 

[Bob4x4]

BTW I prefer Power over smoke

 

[KBurgoyne]

this sounds like a prefilter clog.

 

[yenga80]

this sounds like a prefilter clog.

yeah i'm thinking something is restricting fuel flow; lift pump, something in the tank or lines. Fuel filter was changed 5k miles ago. I'm currently working on building my own fuel gauge tester with parts from mcmaster carr. Then I'll test the pump and make sure that's okay and the overflow valve.

 

[MLee]

this sounds like a prefilter clog.

Yanga8 Do you know where the Prefilter is? and when was it last cleaned. This could be you restrection.

 

[yenga80]

Yanga8 Do you know where the Prefilter is? and when was it last cleaned. This could be you restrection.

ah yes MLee i did clean that already. When i replaced the fuel return and supply rubber lines i deleted the fuel heater and checked that screen. It was clean already. Still getting parts together for a homemade fuel pressure gauge kit. Will see what that reads and go from there. Right now it drives and accelerates fine. Was just poking around the afc and figuring things out for myself and learn how it works; thats when i noticed the housing all the way foward.

 

[MLee]

Ok, good that you did both things. How about the interior of the hoses? all good, any need replaceed because of deteriation inside. Just thoughts, pinched hose/fuel line some where?

 

[yenga80]

Ok, good that you did both things. How about the interior of the hoses? all good, any need replaceed because of deteriation inside. Just thoughts, pinched hose/fuel line some where?

Well I replaced the supply and return lines with new marine rated hose. They were the tough ones to get at that run next to the bell housing and behind the injection pump. The one hose I didn't look at was the curved short one between the prefilter and lift pump. That might need replacing. Thanks for ideas.

 

[KBurgoyne]

those short hoses cost about 3 bucks from genos, and can be changed without removing the pump. the old one is probably dried out so cut it off, and the new one is flexable enough to go on.

 

[hsmith]

I shortened one end of mine just a tad to make it fit better.