73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: stretch86 on March 31, 2015, 11:40:50 am
-
I recently purchased a 86 c10 suburban and being in the rust belt its actualy in pretty good shape. The frame is solid but body does have some rot nothing i cant handle though. Anyways on to the carb the truck runs rough at start up if its cold once warmed it runs ok but stumbles and hassitates when give it gas. Also theres three lines on carb that arent connected two are plugged and one has nothing connected to it heres a pic.
-
First replace that vac line that goes to the pcv as it should not be collapsed like that.
Second go to your local auto store and get a pack of vacuum caps and properly plug those open ports and the other one with the bolt in it and nail.
The vac ports on the thermostat housing looks like someone tried to remove smog equipment and didn't block off stuff either.
With open vac ports that truck is going to run like an absolute turd.
-
won't hurt to run some SeaFoam through the fuel system either.
-
won't hurt to run some SeaFoam through the fuel system either.
I don't recommend this as sometimes the crud in the engine could be what keeps the seals and such from leaking.
-
I ended up putting regular carb cleaner in gas ive heard to many bad things about seafoam so i try and stay away from it
-
Also should i cap just those three ports or the ones near thermostat also
-
Also should i cap just those three ports or the ones near thermostat also
Those should be activated with vacuum which means there should not be any vacuum coming out of those so I wouldn't worry about them. Start with blocking off the ones on the carb and fixing your pcv vac line and seeing how the truck runs first.
-
won't hurt to run some SeaFoam through the fuel system either.
I don't recommend this as sometimes the crud in the engine could be what keeps the seals and such from leaking.
The trick to SeaFoam is a little bit at a time....guys on YouTube and such pour the stuff directly into the throttle body. BAD IDEA. Others put 1/2 to a full bottle in the gas tank. BAD IDEA.
If you put about 1-2oz in the gas tank overtime you fill up......then you will effectively clean your entire carb and valve train.....the "gunk" will get spit out of your exhaust. Just keep doing it until the bottle is empty and you will see the difference.
You don't have to use SeaFoam......just make it a point to fill up for the next three months with Chevron fuel (which has Techron, which is just like SeaFoam and generally stocked right next to SF at your Auto Supply Store)......both your valve train and carb will get cleaned out sufficiently.
Between SeaFoam/Techron and Marvel Mystery Oil.....I've brought dead motors (V-twins) back from the dead.
-
Heres an update last night when got outta work i started truck as usual and noticed it had a higher idle then usual then after 7 or so minutes of letting it warm up it bogged out and stalled. Tried to restart it and it sounded like wanted to fire but didnt then after 5 Minutes it finaly fired up and i went home. Today i capped off vacuum ports on carb changed plugs rotor and distributor cap as well as fuel filter. Went to start it and it started stumbling instantly and stalled tried to restart it and was doing same thing as last night. I took cover off carb pulled linkage and saw gas go in carb checked for spark on an old plug and was orange not blue. So my question is could it have been the coil this whole time or what else should i check.
-
Heres an update last night when got outta work i started truck as usual and noticed it had a higher idle then usual then after 7 or so minutes of letting it warm up it bogged out and stalled. Tried to restart it and it sounded like wanted to fire but didnt then after 5 Minutes it finaly fired up and i went home. Today i capped off vacuum ports on carb changed plugs rotor and distributor cap as well as fuel filter. Went to start it and it started stumbling instantly and stalled tried to restart it and was doing same thing as last night. I took cover off carb pulled linkage and saw gas go in carb checked for spark on an old plug and was orange not blue. So my question is could it have been the coil this whole time or what else should i check.
Spark needs to be bright blue and if its not then you need to look at your coil or ignition module.
-
I had said it was orange and not blue i ended up getting new plug wires and a coil. then ill go from there
-
Im not new to carbs im just new to them with trucks as ive always had fuel injected but the same principles apply to any gasoline engine
-
I put new coil and wires on it now it wont stay idling if i have foot on gas pedal a lil itll run fine with out elctric choke hooked up and with choke plate open. When i have choke connected it keeps bogging out and runs like crap. Any ideas whats going on could it be fuel pump or carb outta wack
-
I put new coil and wires on it now it wont stay idling if i have foot on gas pedal a lil itll run fine with out elctric choke hooked up and with choke plate open. When i have choke connected it keeps bogging out and runs like crap. Any ideas whats going on could it be fuel pump or carb outta wack
I'm going to say there is a lot wrong with this truck and it was probably made to run with horrible vacuum leaks. You are essentially going to have start from scratch and retune everything :(
-
Awesome i did notice plug wires were crap and one was torn badly. I have no clue how to tune a truck carb its a lot different then a atv or motorcycle. how do i do it or at least what are stock settings and where are the screws etc i should be turning.
-
The thing that puzzles me is the old plugs were a good tanish color
-
My uncle has a new quadrajet that was for a 86 cutless with a 307 would that fit work on my truck
-
start by double checking your firing order and use a timing light and see what ° your timing is at.
-
I had a guy come over today and help me with carb determined old carb was junk so put on another one that had gotten with truck. Theres a vacuum port on choke housing where does it go cause it fired up before drove it around then let it sit for a couple of hours and wouldnt start. Ended up opening chokes plate and it fired right up its like it was giving it to much choke and engine was still lil warm. I can post pics later if needed.
-
Also the engine ran great best that ive heard it run and throttle was very responsive no hessitation or anything
-
I agree with the pros here, make certain the electrics work right first, then check for vacuum leaks, last would be the carb. Otherwise, you are chasing your tail.
-
Also the cutlass carb won't work very well on the truck because it's computer controlled.
-
And even though this thread is likely starting to rot it's been dead so long, I want to say I totally agree with what Stewart said. I had an 85 Blazer with the electric Rochester, I did the ignorant stuff to it, unhooked all the smog crap including the electrical connecter to the carb. The truck ran, but it ran like crap. It was a 305. It went from helpless to pointless. I unloaded the truck after that it was so rusted out and the tailgate wouldn't open. The new owner put a Holley on it and cut the tailgate off and ran it for a few years more until the body literally fell off the frame.
-
Eventualy i wanna get different motor for the body isnt that bad for being 30 years in nh and the frames in great shape. Ive capped off vac ports on carb and it does run great good throttle but its diffucult to start at times especially when trucks warm ive also added a manual choke to it as the auto choke kept acting up. My plan is to get a vortec 350 with a nv4500. Build the vortec up a lil bit and fix body with new panels. I also understand the difficulties thats gonna come with adding the nv4500 but thankfuly i found a write up some one did for there 89 3/4 suburban. All in all theres a lot ive gotta do to it and gonna do lil at a time when money and time permits me to.
-
http://67-72chevytrucks.com/vboard/showthread.php?t=610659 heres the nv4500 write up
-
It would help a lot if you put the original-style air cleaner back on and got rid of the two-chrome-pie-plates nonsense.
-
Cant dont have it and im having a heck of a time finding a rear end for it
-
What's your start up procedure?
-
When its cold ill pump it couple of times and pull choke when its warm i forgot what i did cause its been couple months since driven it cause of rear end
-
I always pushed the throttle to the floor twice to prime the intake and set the throttle on the high idle cam. Then I cranked it over. She always kicked right off.
If you have an electronic feedback carb you want to keep all of the smog crap hooked up including the original air cleaner. To dump the smog stuff you need an earlier carb and intake. It'll run like garbage otherwise.
From orbit on my Android.
-
Dont know what you mean by electronic feed back carb i know theres no wires on carb. The only wires on old carb was for electric choke and the idle solenoid. As for the smog stuff theres vaccum lines missing and only thing left on truck is egr and evap can
-
Dont know what you mean by electronic feed back carb i know theres no wires on carb. The only wires on old carb was for electric choke and the idle solenoid. As for the smog stuff theres vaccum lines missing and only thing left on truck is egr and evap can
Feedback carbs have electronic mixture control. The blue connector on top...
google.com/search?q=quadrajet+electronic&hl=en&sa=X&oi=image_result_group&ei=NZuBVe_BEcjxoASqr56YBg&ved=0CB0QsAQ&tbm=isch (http://google.com/search?q=quadrajet+electronic&hl=en&sa=X&oi=image_result_group&ei=NZuBVe_BEcjxoASqr56YBg&ved=0CB0QsAQ&tbm=isch)
Sounds like the PO already deleted that.
From orbit on my Android.
-
The one i put one it didnt have that on either carb
-
It would help a lot if you put the original-style air cleaner back on and got rid of the two-chrome-pie-plates nonsense.
I don't know why you would say that. If the carb is not electronic there is no need for a restrictive air housing. If the truck will be subjected to deep water crossings then i might advocate for something to protect the air cleaner from splash but from what I know about carbs and engines they can use all the air they can get. Heated air from under the hood of an old Chevy is a moot point, the power loss is so small as to be unnoticeable. The six inch tall K&N filter with the pie plate housing or maybe the filter upper housing works just fine. Besides, that little bit of chrome looks good too. The factory style housing wasn't for smog related activities anyway, it was for making the engine quiet. A carb makes a lot of noise when it works at anything outside of an idle, the restrictions in the air box where to dampen those sound waves. The shutter was to help the choke and send preheated air to the carb to help prevent icing during start-up. Both non-issues with a well tuned carb (meaning one that is tuned to work, not one that is tuned for maximum miles-per-gallon, in other words, the lean-burn system that the mid-eighties engines where subject to having).