91 GMC Sierra 4.3 TBI

[wstanley]

Ok here goes,
I have this 91 GMC with 4.3 TBI.. Well its not Running right now Though it was then I messed with things. There was alotta tapping and such when it Ran and it back fired alot (this makes the injectors look all toasted n stuff). Well in order to get rid of the Tapping I tried pulling hte valvue covers and adjusting the Rocker Arms Tightening down and such. well this didnt work and now they seam to be off.. So im Looking ofr a way to readjust them to get them Right so That i can kinda of work backwards and get it back to running so i can run down the problem. NExt thing i was thinking was timing. So i was going to have it running and then Kinda by Ear turn the Distrib. well low and behold i Losen the One bolt on that and I cnat budge the dang thing at ALL it wont turn it wont move it wont do anything, is there a trick to turning the Distrib. that i dont know of on this Truck or is there a reason why it could be hung up and or stuck.

Right now when i try to start it it turns over. Sound slike it wants to start but wont.. when i pump the gas while trying to start it or hold this gas it makes a poping sound But only when i do the Gas I think this is due to the Fried looking Injecter plugs.. Anyone have any advice here I will give it a shot.

Looking forward to lots of replys..
~WiLL
Oh yeah - Money is An Issue

[2000CAYukon]

Here is a good article on valve adjustment: http://www.cranecams.com/?show=techarticle&id=2

To get the dist loose, try spraying some PB Blaster around the base. With the cap off tap (lightly) where you can to try to break it loose. They will get stuck now and then, be patient and you can get it loose.

//2000CAYukon

[wstanley]

Thanks for the Response,
Well, I adjusted the Rocker Arms per Instruction and using the Finger techniqe to spin while tightening then add 1/2 Turn to it. I dont know though if it made a difference. (Puzzled)

I tried to break the Distributor Lose to no Avail just yet. I sprayed some degreaser down in there (Around the Base) with the cap off and tapped on it a bit. It looked like it was moving a lil but I still couldnt be fore sure. Tried to move it with my hands and Notta.. Wont Budge.. I'll keep working at that..

Whats still puzzling me is the Poping Sound when I pump or hold the Gas while trying to turn the Truck over. The only bad thing is im doing this all myself so I dont have someone to sit in there and do that for me while i kinda watch and listen to see where its coming from.

I did notice while i had the cap of the distributor I was messing with the Rotor and it would Jiggle just a little bit (Small fractions of an Inch). The Ignition was on and each time i kinda jiggled it the one or the Other Injector would spray gas alternating. ... So im guessing my Injectors are working Right. (Or atleast they are puttin gas where it should be)

Im still puzzled at the fact that it wont start... Its killin me here. I go out and mess with it jiggle this tighten that losen this and adjust another. Start to try to turn it over and such and still spin spin wanna start spin wanna start spin wanna start pump the gas pop pop hold the gas pop pop.. Anyone any other Ideas???

Thanks
~WiLL

[wstanley]

I asked many the correct way to do this on the 91 4.3L V6 and here is how to do it...

This info is borrowed from Chilton (General Motors Repair Manual 1988-1992)

Valve Lash
This does not work on 4.8L Strait 6

Works with Chevy / GMC V6 4.3L or V8 5.0L 5.7L and 7.4L 1988-1992 (I Know) Could be more yrs.

1) Remove Valve covers and gaskets.

2) Crank the engine until the mark on the damper aligns with the TDC or 0 mark on the timing tab and the engine is in No. 1 cylinder firing position. If the No. 1 valves move, it is in No. 6 firing position (No. 4 on the V6 Engine) and the crankshaft should be rotated 1 more revolution to the No. 1 firing position.

3) With the engine in No. 1 firing position, the following valves can be adjusted:
V6 Engine
Exhaust - 1,5,6
Intake - 1,2,3
V8 Engine
Exhaust - 1,3,4,8
Intake - 1,2,5,7

4)To adjust the valves proceed as follows:
a) Back off the adjusting nut until lash is felt at the pushrod.
b) Turn in the adjusting nut until all lash is removed and the pushrod is not capable of being rotated.
c) Turn the adjusting nut in an additional 3/4 - 1 turn to center the lifter plunger.

5) Crank the engine 1 full revolution until the marks are again in alignment. This is No. 6 firing position (No. 4 on the V6 engine). The following valves can now be adjusted:
V6 Engine
Exhaust - 2,3,4
Intake - 4,5,6
V8 Engine
Exhaust - 2,5,6,7
Intake - 3,4,6,8

6) Repeat the adjustment procedure as directed in step 4.
7) Reinstall the valve covers using new gaskets.

Ok the reason I added this Note was becuase I asked and looked all over for this information with no real luck. I ended up going to the library and getting a book which helped me alot..

So the Status of my Truck

SHES ALIVE
Here is what I did..
I knew id messed with the Valves to get rid of some noise and thats when I really started to run into problems.. So first thing I did was Adjust my Valve lash per the instructions noted above.

Next thing is, My neighbor came over when I was working on Mine the other day. He has an 89 Chevy with the Same Motor as my 91 GMC. Well he said he experienced the same effect with his truck so he replaced the Dist. Cap and Rotor and this cleard his issues up.. Well I went down and got both of these from the Parts store Poped emm on and Still the Same thing.

I pulled the Number 1 Plug wire at the Cap and crossed a screwdriver near the connector for it and made the screw driver ground to the body.. I had someone turn the Truck over and I saw it was getting fire at the Cap. So I went down the Line. I went ahead and Pulled the Number 1 Plug hooked it back to the Cap and had My GirlFriend Once again Turn the truck over.. Humm No Spark.............

So I went to the Auto store once again.. got 6 Plugs took emm home and Gapped them at 0.045 Went threw and replaced each of these. Got back in and Fired Right Up.... And this is where shes setting..

I believe it was a combinition of things. From some of the Valves being over tightend and some under.. The Cap being Bad and Rotor. Plus the Old Spark Plugs So here I am Running Again.. YESSSSSSSS......

And I learned something new to... My Rear Main Seal is leaking On Mine. I thought Id have to get the Oilpan Gaskets and all that to do the rear main but From what the Books says The Rear Main can be removed without pulling the Oil Pan so I get to save a few bucks Right there and get that issue taken care of as well. By simply pulling or Sliding the Tranny Back Pulling the Rear Main Seal with the everything else intact and then using Rear Main Seal Tool J-35621 to put the new seal in..

YEah hawww.. Someone Wanna come hold this Tranny for me??

Laters ALL
~WiLL