I have been chasing this problem for a couple weeks now, and it is absolutely driving me crazy. My truck will not idle. With the choke on it will, but once it comes off, nothing. I figured this was a leak somewhere because before if you place your hand over the carb it would smooth out and idle nicely. So, I changed out all the gaskets, intake, under the carb, under the EGR plate. I also Swapped out any of the rubber plugs that were over any of the vacuum ports not in use. Then I went over every single vacuum line all were ok, I even swapped out a few that looked old.
Next is the carb, The idle screw is at the max, it can't open it anymore. ALso, adjust the mixture screw seems to do nothing. I am sure I could use some assistance with the tuning as Carbs are not my thing.
There is a slew of electronic doo-dads on the carburater that I am not sure if they need to be adjusted or what. There is a thing on the throttle that seems to be working, since it pushes it out more. There is also something on the front end of the throttle plate that may be a TPS or something similar. How, if at all do I adjust these?
This isn't a problem that just accured the truck has been sitting for years and I am in trying to get it going again. For the record the carb is a rebuilt new one, and the tank, lines, and pump are all new so the gas is good clean stuff.

 

VACUUM LEAKS! Get a can of wd-40 and start spraying it around the carb base when it's running. Then around each section of the intake where it meets the block. Any spot that causes to motor to change it's speed while running is a vacuum leak. Also take all your vacuum lines and cut about 1 inch off each one and re-attach....sometimes they tend to rot and break down too. That little motor controls your idle when combined with polution control. Those motors are over-controlled with FAR FAR too much crap. All those electronics around your carb all lead back to the computer.

I would concentrate on the vacuum leaks first. Maybe rebuild the carb because the idle circuit could be gummed up an blocked too. That's a start.

Bob

 

That is the reason I changed the gaskets the second time, I can gaurantee that it is not leaking at the head/Intake, or anywhere under the carb. Just for fun, I went and checked again and spraying didn't cause it to rev up at all. The Carb is rebuilt so I wouldn't think that is the problem, but I may pull it apart and look anyway. I have the big exploided picture of what everything should look like in there, but I am not really sure where the idle area that may be plugged would be.

I agree with too much electronic crap on there, I just figured that with all those sensors on there, there would probably be some sort of adjustment that would need to be made to them. I am really getting frustrated with this thing.

 

I just had another Idea, would I be able to tell if there was a vacuum leak by hooking a gauge up to it. Would it fluctuate or anything if there was a leak or just be real low? That might help eliminate things.

 

If there aren't any leaks then I would suggest that the idle circut is probably clogged as noted by some of the other guys. Had this one happen to me You may want to examine the fuel system for crap (meaning flush yer tank and clean out the lines/change the fuel filter) If the carb was recently rebuilt, it may have gotten loaded with garbage all over again... Bummer! -Restoman

 

[updated:LAST EDITED ON 06-May-02 AT 01:37 AM (EST)]Well. I'm starting to beleive it is something in the Carb. When putting this thing back together, I had the tank dipped and re-lined, a new sender unit, replaced all the rubber lines, cleaned out the stel line (best I could), and put on a new fuel pump and a new filter. The carb was rebuilt at this same time. Since I am no expert I am going to try and find someone to go over the inside of the carb with me again.
One question about the fuel pump, it may not be pumping enough. How can I tell? I put an inline glass filter on there to see how the gas looks, it looks good but I noticed the filter fills up then it sucks it empty then it fills up again. It is Not one steady flow, does this sound right? Could two filters cause too much of a restriction?
I appreciate the ideas, keep them coming.
Thanks

 

Put the fuel line into a glass bottle and it should pump about 1/3 of a pint in ten seconds with the engine being cranked. That's the fuel pump output test for your engine.

Bob

 

 

Well I think I solved it. Fuel pump checked out ok. I pulled the Carb apart again, still the same, I went to the parts store just to see how much one would run me. It was cheaper than I thought so I picked it up, through it on and drove around all afternoon with out it stalling once. I didn't even adjust anything on it yet. I have my fingers crossed that this is it, so far so good.