Fuel Screw

[JQuam]

hope fully somebody has the magic answer for me. Ive removed the collar from the fuel srew and completely bottomed out the screw with absolutely no sign of runaway!! Am i missing sumpn here?every where i look people r talking about being careful on adjusting so you dont get runnaway. can i make a new longer screw to try n get more out of it?

side note: put my 3. 54 gears in and am going to tow this weekend,hope i like them,took the ol smokey pin out it was actually bottomin out?!?! old pin feels better up top but not as crisp. Need to get a 16cm housing its slower spoolin without the 4. 10 gears. Thanks for all the help guys!!

 

[JLEONARD]

From what I remember reading here over the years (and that itself is scary) bottomoing the fuel pin doesn't always cause a runaway... . and it doesn't always cause it immediately. In other words it may happen next week or next month.

That's how I remember it... of course my memory ain't what it used to be... :-laf:-laf

I'd sign my name but can't recall it at the moment...

 

[TSkibyak]

I have about 10,000 mile on my first truck with the screw bottomed out no runaway yet. Different trucks and people will have different results.

 

[cerberusiam]

From what I remember reading here over the years (and that itself is scary) bottomoing the fuel pin doesn't always cause a runaway... . and it doesn't always cause it immediately. In other words it may happen next week or next month.

That's how I remember it... of course my memory ain't what it used to be... :-laf:-laf

I'd sign my name but can't recall it at the moment...

You got it right, oh amnesiac one. :-laf



Wear on the internals will play a big part in how far you can turn that screw. What may cause a runaway on a high mileage pump will work fine on a fresh one.



Approach with care and validate the setting with some tests.

 

[Tippin Spotted Cow]

I would imagine that the idle screw, high idle screw, condition of the lift pump, injectors, timing, and many many other things would attribute to the runaway or not issue also.



I'd just say have a game plan ready for if it ever does happen.

 

[R C Cola]

Shouldn't the solenoid turn the pump off when you turn off the ignition key, and if that wasn't working you should know it ahead of time ? Then the manual shut off lever on the side of the pump, then if neither of those work you will have to cut off the air supply " but not with your hand " and removing the tube will take time ! Am I off here ? ?

 

[cerberusiam]

Shouldn't the solenoid turn the pump off when you turn off the ignition key, and if that wasn't working you should know it ahead of time ? Then the manual shut off lever on the side of the pump,

That works when it is running away on fuel, but, what if it is not fuel feeding it?





Torque tube off and a piece of board handy to block off the air flow is the ONLY sure way to stop a runaway.

 

[JQuam]

I guess ill just keep my fingers crossed really tght for now!! so does a guy dare make a custom longer one????

 

[cerberusiam]

so does a guy dare make a custom longer one????

NO!!!!



Crank that rack back to far and BOOM!! You will have a VE full of parts, loose parts that looks like a jigsaw puzzle.

 

[R C Cola]

Longer screw hmmmm ..sounds fun

I would be afraid to try it. The shop that did my rebuild said that he set the adjustment based on fuel flow volume, about 120 for mine. If going over the max setting wouldn't you want to know exactly how much fuel it is getting and that it can handle it. Should cost about $200 or so for R& R and set the flow on the machine.

 

[R C Cola]

What if it is not fuel feeding it ? ?

Cerber, sorry... I don't unnerstan . Mine dies when it has no fuel for whatever reason. And yes I have had it happen.

 

[JQuam]

thanks guys! anybody know y my ol smokey fuel pin was bottomin out?

 

[cerberusiam]

Cerber, sorry... I don't unnerstan . Mine dies when it has no fuel for whatever reason. And yes I have had it happen.

There is 3 gallons of fuel in the crankcase, just be happy it never got to that point.

 

[Tippin Spotted Cow]

My solenoid has been out of commission for a while now. The manual shutdown lever alone doesn't work. I have to push my throttle back toward idle (the heavier gov spring keeps it from hitting the idle screw when you let off the gas) and hit the manual shutdown at the same time. If I only go for a short run and the motor never gets warm, the truck wont shut off that way either. I keep a long flat head screwdriver on my dash up against the windshield to back the fuel screw out when that happens. Might I suggest a similar back up plan?

 

[Jgolden]

I'm older than Jay, but he is way older in Diesel years, but I also recall mention that sometimes the threads on the screw suffer when the collar is removed and you can get a false bottom.

Are the stock fuel screws all the same legnth?

 

[JQuam]

I dont think im getting a false bottom. I chased the threads on the lathe after removing the collar. But ive been wrong before(multiple times,ask da wife). Thanks for the idea to check it though it hadnt crossed my mind(open space). ill do some more research and c what i can find.

 

[R C Cola]

Fuel in crankcase ?

Cerber..... I understand that the oil will burn but, how would it get from the crankcase into the injection pump ? Inquiring minds need to know !

 

[Jgolden]

Seals in the turbo fail and oil goes in the intake? I guess that could happen so, I guess it has. Just my guess.

 

[cerberusiam]

Cerber..... I understand that the oil will burn but, how would it get from the crankcase into the injection pump ? Inquiring minds need to know !

It doesn't need to get into the injection pump, just the combustion chamber.



As was mentioned, failed turbo seals will inject oil right into the intake air. Worn valve guides and seals will allow oil into the combustion chamber, worn rings will allow oil past them on intake stroke.



What generally happens is the rpm creates enough crankcase pressure and oil haze it starts blowing the oil past weak areas and it feeds on it. The more rpm the more pressure and the more it churns the oil into vapor that will be fored into the combustion chamber.



Even on an engine that would test nominally good for compression, leak down, etc, at a certain point the engine will start a siphon from the crankcase. A good part of ring sealing comes from the high pressures on the TOP side of the rings. They won't seal with crank case pressure and it doesn't take much to fill the cylinder with oil haze on a down stroke.



Once they start a siphon you either cut off the air or run far and fast cuz when it comes apart you don't want to be anywhere around.

 

[JLEONARD]

sometimes the threads on the screw suffer when the collar is removed and you can get a false bottom. 

Are the stock fuel screws all the same legnth?

That makes sense about the threads. .

I'm betting the screws are the same length.