Fuel Screw...Just to make sure...

[Idually]

Hello, again, guys. This is the 1991 CTD that is going into my RC. I was looking at the inj. pump tonight(Don't want to look at my 1993 W-350's yet... no guages)



Tell me... Is this it? Can any one tell if it has been turned in? Is that the "collar" everyone talks about, that is near the head of the screw? Remove it? What do you think?



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BTW... There was a cover over the screw...

Thanks again.



Andrew

 

[pepecat]

yes, this is the fuel screw with the lock collar still intact. Also pictured is the wire connector (ground or power?) to the fuel shutoff solenoid. . if this falls off , the truck will shut down and/or will not even start! Nice pictures by the way! tight angles...

 

[BushWakr - RIP]

Yep, that's the fuel screw... and, it is definitely already cranked in pretty good from the way it looks too... ...

The wire 'pep mentioned is also one of two that are normally on that contact. One is a trigger signal and the other is a "maintainence" signal... either way, as long as that thing has enough power to hold the solenoid active your ok to go... but that fuel screw is really in there a fair bit... hmmm.....



pb. .

 

[flathead6]

What does the fuel screw contact in there? When I adjusted mine it only went about 3/4 turn before stopping. The lock nut was free and there was still maybe 1/2" of threads showing after the locknut was tightened back down. But there was some resisitance there to turn it any further and I was hesitant to force it any.

 

[flathead6]

Hmmm, After posting I got to thinking and looked at the photo again. Mine didn't have the lock collar so that probably accounts for about the same amount of exposed threads... But my EGTs are fine, and no smoke, even with the cone adjusted full and the star wheel bottomed.

 

[Greenleaf]

Contacts the tensioning lever. If the screw is bottomed in it's ("O" ring) bore, you are now pushing aluminum out of the bore.



-S

 

[flathead6]

So thats a little too far huh?

 

[Idually]

Thanks guys. I was going to look at the screw on my '93, for comparision, but haven't had the chance.

I have not adjusted the screw on this one. This is how I drove it home. I wasn't seeing smoke, but there are any guages on it either. Once I fire it up again, then I can do a bit of playing.



Do you suppose I should back it out a bit? If so, how far? I get the feeling the P. O. did some tinkering, so I would like to get back to a more "stock" setting, for now.



Thanks again!

Andrew

 

[Greenleaf]

One can set the fuel adjusting screw where ever one wants to..... providing the engine will return to (slow) idle speed w/out a time dalay AND/OR you can pull a loaded trailer up the steepest hill you are likely to encounter with out driving the gauge past 1300°F



With out a gauge to monitor the exhaust temps, you can turn the screw in as far as you like providing you have enough self dicipline to keep your foot out of it and/or not put the engine under any condition(s) that will cause the pump to call for extreamly heavy fueling for an extended period of time.



Case in point. I simply "drive" my trucks and rarely see over 8 psi and 800/900 °F exhaust temps. Should I perform questionably leagal manuvers, things get ugly.



Just drive it like your sister would and install the required gauges as time permits.

 

[flathead6]

So even if it is turned in to where it is bottomed out (or naturally stops), and the idle is adjusted back down, then the pump is still functioning OK right? And everything else is too as long as EGTs are watched and idle stays where its supposed too?



Not sure what you meant by "pushing aluminium out of the bore" if the screw wasn't "tightened" but instead just "bottomed out".



I'm trying to get everything tuned right and don't want to mess things up due to ignorance on my part. I can suffer bad mileage or poor performance and then adjust things back but I sure don't want to tear anything up in the process. Temps and boost are monitored, but I worry about what I can't "see" happening by adjusting something way out of whack.



Thanks,

 

[dpuckett]

Flathead6-

Your picture shows about where my mildly tuned pump (stock internals) was set, and still is. ~120mm the guy at the pump shop said last spring- 50% over stock. Yours could be higher than that, or closer to stock. The only real way to tell is to hook up a boost gauge- stock for nonIc is around 22psi; stock IC is in the mid to upper teens. This allows a slight haze under WOT, and EGTs in the neighborhood of 1000-1100 pre-turbo. I had 28-30psi with the H1C and stock exhaust housing when I first got the truck. I now peg the 40psi gauge with the PDR HX35.



Daniel

 

[flathead6]

Daniel,

The picture wasn't mine but my screw stopped about where his was. I'll check my boost/EGTs and compare to "before" next time I can take it out. Most boost I could ever get before was about 20-21 and EGTs below 1200, pre-turbo.

Thanks,

KRB

 

[Greenleaf]

When the screw is turned in to the point it bottoms in the O ring bore, you have not caused any damage to the pump so as long as the engine operates normally. Should you attempt to turn the scew in further the screw O ring groove will cut into the pump top threads and push the aluminum threads out of it's way. You CAN do this as I had a pump in here that very same thing had happened.



Of special note is the fact that thye screw is pushing agains the tensioning lever which is held rearward by two very strong springs. When you reach the point when the screw hit's bottom it's "kinda" tough to recognize this. Pay close attention to the force exerted to move the screw into the bore.



FWIW;

As I have stated before... ... some pumps will not tolerate an agressive setting and thus begin to have little throttle response. I believe that the pumps which can operate with an agressive fuel screw setting are high milesage units or in some cases just weak compared to a fresh pump. This has been my real world/work experience.

 

[BushWakr - RIP]

Andrew, I sent you and email with some tips/info... I now see the collar AND the heavy washer are still on the screw... .



pb... .

 

[flathead6]

Had some time over the Holiday break so I backed the screw off some (1/2 turn) and set the idle back to 750. It was just just turned to the point of feeling resistance before but didn't want to take any chances with screwing up the gov after reading a bunch of search threads. Not sure what the previous owner had done to it anyway. I may play some more with the starwheel and smokescrew for now, both are maxed at the bottom now. Maybe next Xmas I'll ask for some injectors and gov springs! But then of course I'd need a new transmission...

 

[Idually]

Thanks again guys. I do appreciate it.



P. B. I never recd an e-mail about this... Could you try to resend?



Thanks!

Andrew