HELP!!! idle ajustment?

[**ICEMAN**]

on my buddies 1990 the power adjust screw was turned in as far as possible with the steel collar on. we removed the collar and gave it 5 turns in,,,5 clicks clockwise on the star wheel and rotated the diaphragm a 1/4 of a turn clock wise. i have the idle speed screw backed the whole way off so that the linkage doesn't even touch the idle screw and the rpm's are very high. how do i control the idle speed with these settings??? i put the star wheel and diaphragm back to original position and set the power screw to 3 turns in so he could drive it and the idle is still a little high with the idle screw backed completely off. we drove it and the 3 turns of the power screw can definately be felt as an improvement but would like the give it a little more and be able to control the idle.

 

[Matt S]

WOW!!! 5 turns in is WAY too much. At 4 turns in mine was not really driveable due to EGT's. At 1. 5 turns I don't have any EGT trouble, even with a 12 cm housing. Get an pyro on that truck. It is cheaper than a new engine. Don't try a no load RPM test because there is no gov at that much fuel.

 

[Lil' Dog]

Holy Crow!!!!

Turn that screw back out 4 turns or that engine is gonna be a hunk of goo, I'm not kidding.



My 89 I turned it in 3/4 of turn with the collar on, diaphram adjustment, and the spring adjustment to the star wheel. Then did the BD injectors and I could get 1250°F in 5th gear empty never mind loaded at 24 Psi boost.



Buy some darn gauges!!! if you're gonna boost that sucker.



Since you have the fuel screw so far in, you can't control the idle. With the original injectors, the pump life is gonna be low as well.



Ease up on the reins!!!!



J-eh

 

[**ICEMAN**]

thanks for the info. this was the first experience i have had with a 1st gen truck. as you can see in the profiles of my trucks i have done plenty of tweaking and know the importance of the gauges and made my buddy aware of it. i got him talked into getting a pyro to start with. he backed the power screw out to 2 turns in from stock and it idles like normal now(truck is tach less). he then set the diaphram to 1/4 turn clockwise and 5 clicks clockwise to the star wheel. runs good! i told him take it easy till he gets the pyro in.

p/s: him getting the idea to tweak his pump is all my fault. i let him drive my '01 with all the goodies in the "on" position and set on high.

 

[BushWakr - RIP]

The guys are right... . you narrowly missed a thermo-nuclear event in your own driveway !!!

FWIW the dual threaded linkage on the drivers side of the pump is used to make sure that the idle stop pin contacts the stop. (that may be why you could not get the idle down as it was not returning to end stop).

There is a proper "break-over" setting/spring that needs to be set as well, when you 'up-adjust' these things. That is a funny little 2 ended spring with a small pin in between the 2 ends, it 'buffers' the throttle action. (Does not effect power)

Last, if your friend has an auto trans. he'll need to keep a serious eye on trans temps with those power adjustments. Mine surprised me to say the least.



Good luck !



Bob

 

[**ICEMAN**]

thanks,

it's a 5 speed

what is a good setting for the star wheel on his 1990?

i have mine on my 94 turned all the way in. is it ok to do this on a 1st gen. ?

where is the best setting for the diaphram? we have it set 1/4 turn clockwise now.

bear with me here fellows,,this is my first time with a 1st gen.

 

[Lil' Dog]

With the larger 18. 5cm housing and the smaller fuel pump, my 89 had the star screwed right in tight and the smoke screw 1/4 turn in from being all the way backed out. Kept the smoke down off the line but dumped the fuel to it as soon as you got about 5 psi boost. The best way to check the fuel delivery pin is to take it out and mark the spot of the steepest taper. That goes toward the front of the pump/engine as the follower pin comes out at 9:00 leaning over the drivers fender.



J-eh

 

[BushWakr - RIP]

Here's a pic of the internals of the diaghram/plunger end attched to it. The pic (ok I shouldn't quit my day job) shows the position in which the fuel delivery rate is fastest. The pin sticking in from the left/bottom is the one that gets stuck either in or out.

Here's the link:



https://www.turbodieselregister.com/forums/showthread.php?threadid=22290



Hope this helps!



Regards, Bob

 

[hdm48]

just for info's sake, the reason you can't get the idle to come down is because the TPS has a limited amount of travel due to the machined grove in the mount which stops the TPS from being adjusted back after the idle position change. look under the TPS and you will see it. what i did was extended the grove a little [1/8th inch] and now i have plenty of room for adjustment.

But do follow the wisdom of the other members and get some guages befor you melt your engine.

 

[Matt S]

I don't think a 90 would have a TPS.

 

[hdm48]

well slap me silly! your right Mat S. a '90 with out o/d has no need for a TPS. sorry

 

[**ICEMAN**]

Originally posted by **ICEMAN**

thanks,

it's a 5 speed