NEW PROBLEM(S):

[Stewart G Griffin]

Good idea.

How do i check this?

[VileZambonie]

try picking up on the diaphragm or simply pull it off and check

[Stewart G Griffin]

PT.3
You'll have to forgive me, as i know alarmingly little about cars;  i may think that i do---as far as specs, options etc., but i really know jack about the mechanical workings of cars.  i'm not an engine person---more of a driver.

So what i'd like to propose for this situation, if i may ask of all of you, if for a highly detailed, step-by-step plan of attack and diagnosis and action.

To make it simple, the problem is:

At rpm's below 900ish rpm, the engine will stall out.

1)it does not matter if in gear or not

2) the idle speed screw is not the problem, but i'm willing to "test" this because of the new highly detailed, step-by-step, plan request.  As an additional note when the truck was running normally, which was only 5 days ago, it idles at 500-600rpm in gear.

3) when testing both vacuum advance canisters, i moved the lever up (most advanced position),put my thumb over the hole and in both instances the lever went back to resting position.  After i took my thumb off the hole, there was a puckering sound in both instances.  i'm not sure if this is a valid way to test vacuum advance canisters?

4) the engine runs ok enough at rpm's of 1000 or higher.  Pretty much just like before.

5)At 900-700 rpm the engine sounds (and feels vibration-wise)like a pro-stocker with a very radical cam,---whereas normally my engine is normally sewing machine smooth at those rpms.


Please, pretty please, pretend like i'm 5 yrs old or something and i'm trapped in outer space or something and the only way for me to escape is for me to fix the problem.  i know we can do it.

[Lt.Del]

5)At 900-700 rpm the engine sounds (and feels vibration-wise)like a pro-stocker with a very radical cam,---whereas normally my engine is normally sewing machine smooth at those rpms.

Head gasket blown?  Do a compression test.

[Irish_Alley]

stewart still having problems?

[Stewart G Griffin]

Yes, sorry it took so long to get back.  i have been working quite a bit of hours lately----i suppose that is a good thing with today's "supposed" bad economy.

i will update as soon as i can.  i have a service manual on the way.

[VileZambonie]

Did you make sure the EGR valve isn't hanging open as suggested?

Did you see if holding your hand over the air horn made a difference?

[Stewart G Griffin]

i haven't for several reasons:

a)i was/am very busy

b) i'm not quite sure how to test the EGR valve;  i need step-by-step, very detailed instructions. Preferably with pictures.  The Sgt's. post on changing a ball joint is an excellent example of what i'm talking about.  i suppose for someone who really knows and teaches, it's easy to blurt out the answer in a a short fragment or sentence--my dad taught college and he was/is the same way.  Don't get me wrong---i definitely appreciate the help and concern, but i really don't know jack about cars.  i thought i did, but i definitely don't.  Thus, i need to be spoon fed the info----just like i'm 4 years old or something----because, really, when it comes to cars, i am 4 years old or something.

Yes, i'm asking for a handout.  But what's wrong with that?  If people have an objection to this way of teaching----and some people do (can't imagine why), then that is sort of ok too;  i've ordered a service manual and am looking on youtube for videos on how to check EGR and other things. 

c)  About the air horn thing.  i'm not sure if i can do it right now because if the engine stalls out without my foot on the gas, by the time i get my hand to the carb, the engine is no longer running.  Now, i could jack up the idle speed screw to prevent this, but i don't want to.  Thus, i've ordered a remote starter which i feel is a good thing to have anyways.

But again, thanks for all the help.  i'll report back ASAP.

[Stewart G Griffin]

Ok, so anyways i changed the pcv valve----because it needed changing anyways because it's been on there since i got the truck and it's only $2.95 anyways.  A little improvement but really the problem is still there;  It may not stall out anymore but the idle is still rough to the point where the engine is barely running at 600 rpm.  i think if the engine really got warmed up, it would very probably revert to stalling out.



Next, we get to the EGR valves.

By the way, the service manual came in and it is fatter than 2 phone books.  And the manual was saying that there are 2 types of EGR.  How do you tell if you got positive or negative feedback EGR?

i took this one off the engine for inspection:


This other one, i took off the 305 i have sitting in the garage for comparison:


a) for the top one, the one off the truck, i was able to push the diaphram in and if i kept my finger over the vacuum supply opening, the diaphram would stay inwards until i took my finger off and then the diaphram would move back to resting position.

2) How do you test the vacuum advance canister?  i've read that you move the lever to the most advanced position and put your finger over the place where the vaccuum hose would connect and it, the lever, should not move until you release your finger?   Suprisingly, the manual, says nothing about testing vacuum advance, or at least i'm unable to find it.

3) P.S. i should also mention that when the engine is "idling", or doing it's best attempt to "idle," the vacuum gauge swings broadly all over the gauge in rhythm with the engine.

[VileZambonie]

put your other egr valve on it and don't bother hooking up the vacuum hose. There should be no vacuum to it anyway idling (make sure of this) and see what it does.

[Stewart G Griffin]

Sooooooo..........you're saying i should put the one that came off the dormant 305 on the truck?


P.S.
i have come to the conclusion that the so-called "old-school" setup, that being carburetor and distributor, is not nessesarily easier to diagnoise and repair than, say, a 98 or 2008 silverado.  In fact, i believe that the "current" electronic technology may even be easier to fix.  i think the key is familiarity.

Example:  This post is 3 pages, lasted one week and problem still not solved.

My main reason for trying to fix it myself is mainly distrust of the dealer and/or private shop.  i'm not saying all shops and dealers suck, i just haven't been able to find and keep a good one.  i am not sure of why today's dealers can't fix cars.  i don't think it is due to incompetance, but then again.........  .   Maybe they don't give a dang.  Then again, the quality of everything seems to be going downhill.   i don't really have much time to mess with this, but i don't see any other choice.  And you wonder why gm is dying.

The second reason is that i just find cars interesting.

If i could find a good shop, i would take it there to have it serviced due to my time constraints.

i consider the setup of quadrajet and HEI is sort of like hamburger, fries and coke;  Good solid dependable food.  (and not junky crap like McDonalds, BK etc, i'm talking about hamburgers served at deli's or sit-down type restaurants, i.e., Shoneys/Denny's etc.).  Whereas coil-on-plug electronicized ignition and Electronic fuel injection could be considered Fillet mignon and aspargus on the side with maybe some wine.   Both are good food, but the second one is more sophisticated.

[Irish_Alley]

I will try to suggest this again try a tune up. check your wires at night with engine running and one less thing check for a vacuum leak around the manifold or anywere else. i don't think egr valve has anything to do with it cause you can just bock it off and the engine runs good, the distributor simply because the engine is running

[JJSZABO]

3) P.S. i should also mention that when the engine is "idling", or doing it's best attempt to "idle," the vacuum gauge swings broadly all over the gauge in rhythm with the engine.

Stewart, I feel your pain.

Could you get us a video of your vacuum gauge hooked up?  A vacuum gauge can be an invaluable diagnostics tool.  This could lead us to a direct fix.

[Stewart G Griffin]

i will try;  i tell you it is bizzarre.  If i rev it up to 1200 or so the vac gauge needle will stabilize out at it's normal place, which to me (maybe i'm reading it wrong) is at 40-50 lbs. or 6 o'clockish.  Then, when i let completely off the pedal, with each "rump" of the engine, the needle will move from 9 o'clock to 3o'clock in exactly rhythm with each "rump."

i'm thinking it might be that flapper door thing on the right-side exhaust manifold ( i still have the stock ones installed).

[JJSZABO]

Stewart, I am confused

Vacuum gauges read in inches of mercury(in Hg).  What are you reading that shows 40-50 lbs?