trashing fuel pins

[MEby]

What would happen if I removed the fuel cone(you know the one everyone takes to the dremel. ) ? Would I hurt the pump any? More importantly, would the small pin that rides against the fuel cone come out any further and allow more fuel? thanks



matt

 

[dpuckett]

There were a few who tried this a few years back, and had lots of smoke and EGT to go with it. Smoke control is difficult at best.



I dont think any harm would result from removing the cone and seeing how it ran. Ironically, I have read where some actually REDUCED turbo spool by adding too much fuel at the bottom end. There will be naysayers who claim you can cause a leak at the guide pin. Having had that apart myself, I dont see how, as the pin will hit the back of the well before it pops out.



I think Old Smoky said the guide pin comes out a bit more than the cone will allow, thus you would get more fuelling. I have ground fuel cones enough the guide pin leaves the surface of the cone at full boost.



Daniel

 

[Greenleaf]

I have studied the witness mark via several different cone profiles and can confirm the profile can be deep enough as to have no effect on further movement of the fuel pin.



Yes, smoke and EGT's can become problematic espessially if the AFC is rendered inop/bypassed.



There are different fuel pins as well. I cannot say for sure and one would need to confirm this with a body that has removed and measured several from different pump models. There likely is different lengths. They don't all look alike however I have not measured them.



The reverse lever moves the fuel pin. The reverse lever can (and will under the proper or improper conditions ) bottom out against the plug that contains the pin O ring. Thus when bottomed, the fuel control cone (profile) has no effect..... it has moved as far as it can.



I have operated my engine with the control cone removed. It did not leak. The pin moved to the opposite side of the bore... ... ... I still don't understand why it didn't leak. Nor do I understand how it traveled that far as the reverse lever bottoms out. My guess is it POPPED out.



The location of the O ring is next to the control cone bore , not inside the plug.



When you get a leak, there will be no doubt.

 

[Moab4x4]

Once again I have been enlightened here. I thought that o-ring was closer to the plug end than the bore end. Whew! I feel better about my grind now. I leave the pin for the bottom 1/16" fuel pin travel or so. I was hoping to leave the top for min fuel for economy and leave the valet switch off most of the time, and grind for full fuel at max pin depth with boost. My plan is to tune the fuel screw for max power with manageable EGTs with boost.

Is is possible to bind the reverse lever during assembly? I don't seem to see any fueling difference now with or without boost and it seems like I have too much fuel at low end. hmmm I guess I will have to take it apart again and be a little more careful putting the top on.

Thx again for the education.

Ken

 

[PToombs]

Ken, I think the only way to cut fuel down low is to back out the screw. I know this goes against all our principals, but some times sacrifices have to be made! #@$%!

I might be wrong on this, I hope Scott will give his . 02!

 

[dpuckett]

I have had a few guide pins get stuck at the minimum fuelling position, and cause a lack of power (or in this case, stock power:-laf). If the guide pin doesnt push out, the reverse lever wont move, cutting your fuel by about half its full potential with a moving reverse lever. It sounds from your description like that may be a possibility.



DP

 

[Moab4x4]

Thanks DP

When I had the pump apart, I did notice that the guide pin was a little sticky. What lubricant should one use on on the fuel pin and air side of the guide pin?

I wouldn't be surprised if that is my issue. I haven't held much boost for long to try to dislodge the pin, I haven't had enough load or highway yet. I may just go find a mountain real quick before I pull it apart.



On Edit, I took my drive and I REPENT !!! I had backed the fuel screw out too far and what an abomination. It is not worth trying to save the around town mileage. I admit that while I didn't smoke hardly at all while leaving stoplights, the power tradeoff is not worth it. I will now return to the proper setting of Oo. Oo.



Ken

 

[TBurow]

i have had my fuel pin removed for about 6 months with absolutely no problems yet, (yet!) it seems to pull a lot harder and will be easily controlable with the right foot. just dont floor it at takeoff and it wont smoke at all. power comes on instantly when you get on it at any speed. so far it seems to be good for me, but i dont tow anything. i did it just to eliminate 1 more thing that could screw up and cause low power.

 

[MEby]

so far I havent removed it, I just wanted to see if it would hurt anything if I did remove it. btw how far have you driven in the last 6 months

 

[TBurow]

maybe 15,000 miles i drive it when i have to pick up something or to drag out gravel trucks thet get stuck in my front yard, and just to goof off. kinda a waste of a good truck but at least i have fun.

 

[Moab4x4]

Found my issues:

#1 valet switch solenoid valve passes boost open or closed. #@$%! Contamination from the recent work I did or bad seal.

#2, I didn't have the fuel screw locknut as tight as I thought and it had backed out 1/4". It died at a stopsign when I let out the clutch.



For now adjusted nicely running without the valet.

Thx for the tips.

Ken