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carb jerking problem...help plz!

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Old 11-06-2009, 01:01 AM
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carb jerking problem...help plz!

well i have a 1984 camaro SC with the 2.8L carb. t-5 trans. now the ignition coil and control module died, so replaced those. also installed a fuel flow regulator (mechincal pump not working so got a 9psi electric one on it) new cap, plugs, rotor button. at first, b4 new iginition stuff and regulator it jerked and seemed like it was flooding. but now it just plain jerks. when it idles theres a miss...but when im on the gas, no miss. and at full throttle no jerks. but at light accel and trying to keep constance speed, jerking. any ideals? all welcomed, this is really starting to drive me crazy! any questions ill do my best to answer.
Old 11-06-2009, 01:55 AM
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Re: carb jerking problem...help plz!

had a similar problem caused by moisture in the distributor cap
Old 11-06-2009, 02:07 AM
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Re: carb jerking problem...help plz!

hmmm but my cap is new and sealed, made sure. i now when my coil got wet it ran like **** b4 it died but got a new one sealed
Old 11-06-2009, 02:13 AM
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Re: carb jerking problem...help plz!

could the choke be flopping open and closed?
Old 11-06-2009, 02:21 AM
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Re: carb jerking problem...help plz!

i dont think so...hmm how do i check? i now i replaced a few things choke related so that it wouldnt stay closed (?)which ever that happens to warmt he motor up quicker. how do i check? bc it only jerks in gear going down the road. when idle or not in gear its fine.
Old 11-06-2009, 02:28 AM
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Re: carb jerking problem...help plz!

i have one of those in the garage. i can let you know more about how it works tomorrow. i'll look and see what could cause that. you may try checking for vacuum leaks both visually and with some starting fluid with the engine running. just spray around the base of the carb, intake gaskets and vacuum hoses. careful not to set the engine on fire.(happened to a fellow mechanic/friend)
Old 11-06-2009, 02:38 AM
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Re: carb jerking problem...help plz!

sounds like low fuel pressure,have you changed the fuel filter?
Old 11-06-2009, 02:42 AM
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Car: 82 S10, 83 280ZX, 84 Z28
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Re: carb jerking problem...help plz!

yeah. sounds like a lean skip. look at your spark plugs. if the fuel system is right, then check for vacuum leaks
Old 11-06-2009, 02:58 AM
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Car: 92 25th anv camaro rs
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Re: carb jerking problem...help plz!

i would deffently set the car a fire lmao. and shouldnt be low fuel pressure, thats why i got the regulator on it, the pump was 9psi. but we didnt set the pressure by guage...hmm what would be a good setting? for it. and ive checked plugs b4 and they where normal i guess, not black didnt smell of gas. and ya im almost sure there is a vaccum leak, but would a small leak seriously cause that much problems? i have found out tho that the master brake cylinder is leaking in to the brake booster...
Old 11-06-2009, 03:30 AM
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Car: 82 S10, 83 280ZX, 84 Z28
Engine: 355 smallblocks..na, 2.8 turbo
Transmission: 85:th350, 84:700R4
Axle/Gears: 85:ford9 4.85, 84:stock 3.24
Re: carb jerking problem...help plz!

if its not ignition related it would most likely be running lean if the spark plugs are not black. things other than the carburetor to look at would be advanced ignition timing or vacuum leak. if all that checks good i would try another carb
Old 11-06-2009, 03:38 AM
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Re: carb jerking problem...help plz!

o! that reminds me, something to throw into the puzzle here, the timing isnt advanced, it isnt factory. no its roughly at -6* (yes made up but the distance to 6* and where its at now is bout the same) funny thing is thats where it runs best at right now, advanceing it makes it run horrably. hmm i do believe the carb needs rebuild as it 4th and 5th there is like no power at all, feels like the 2nds arent open all the way. ironiclly they are vaccum 2nds lol.
Old 11-06-2009, 04:09 AM
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Re: carb jerking problem...help plz!

That sounds exactly like a bad coil wire. Now, maybe I haven't had enough coffee yet but, I can't remember if your year car would have a remote coil or coil in the cap.

A little background so you don't think I'm just making stuff up. I was a Chevy mechanic (GM certified and ASE Master) back in the eighties and early '90s. I remember this condition on many v-6 cars because at first it was difficult to diagnose. It wouldn't show up on the scope because you couldn't properly load the engine in the shop. And, since it only happened at light loads and not heavy acceleration, plug and coil wires were automatically ruled out. I found the solution by accident and fixed 95% of cars with that problem after that.

I don't know if any of this helps but, I thought I throw it out there to give another thing for you to look at.
Old 11-06-2009, 04:13 AM
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Re: carb jerking problem...help plz!

its the remote coil pack, right on top of the passenger side valve cover. and bad coil wire...? like the wire that goes from the coil pack to the cap, the same wire thats in the plug wire set? or a different wire?
as a side note if its the wire that comes with the plug wires, im throwing .45 bullets at the car from a colt double eagle...
Old 11-06-2009, 04:21 AM
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Re: carb jerking problem...help plz!

i would run the timing at stock timing. then trouble shoot from there. tuning it perfect requires the default variables to be well, default. its like tetris the game. everything has to be in perfect order. i dont think changing the time according to masking the problem ratio is helping. sure it may run a little better but its not "fixing the problem" Its more like just living with it. Jerking? I have a question and this is important to tracing back steps. What was last 24 hours you remember b4 the car started being a jerking jerk. Does it jerk in wide open throttle? if no, then its a sensor most likely.. The coolant sensor caused a lot of problems to computer controlled cars, Assuming you got the computer right? But most likely if the fuel is coming at 9 psi, and the spark plugs are gapped and NOT black, then yeah, it could be stupid sensor. I just scanned over the Haynes manual on carbs for v-8/v-6, I could be wrong, but i was reading a carb does got a TPS< and the mixture control solenoid could be stuck or constantly running lean. or the tps is maladjusted and running so rich setting, that the computer is restricting fuel flow due high flood. Can you rev in neutral with no miss? whats your temp gauge read after driving typically, if the coolant sensor isn't bad, or even a wire broken, the car will not go into close loop mood causing a default map value to cause the "limping" you're experiencing. at wide open throttle WOT, the computer bypasses all sensors pretty much and it runs awesome. sorry, but can you rev in neutral? oh, need to know the model carb model #, for more research. one model carb calls for .25volts at idle for the tps (throttle positioning sensor) and another carb call for .50v at idle. im a tpi junkie learning all i can. I speak my maybes and suggestions aloud to spark further chain reaction of brainstorming among the many here and open the book to ideas and computer logic. my understanding of your ride needs complementing ideas from other more people on the site, not an all one answer dude. But knowledge is a step higher than most my age.
Old 11-06-2009, 04:51 AM
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Re: carb jerking problem...help plz!

ok lets starting answering here umm i bought the car after sitting for 7 yrs and the pump wasnt working, timing also came like it is, and thus the new pump on it. when the new pump was on it, with all the vaccum leaks, it was jerking but felt like it was flooding. well fixed all visable and known leaks and got a fuel flow regultor on it. now it jerks, still. and i would put it back at defualt but it wont stay running some times and it just barely runs, side note has a very high idle or 3000rpm trying to fix that to but no luck, but ill set it back to defualt as soon as a get a timing gun again. full open throttle it runs good, cept in 4th and 5th gear. ya sadly have a comptuer, until i remove the emissions stuff then i think i was told i could dump the computer, but i need to invesagate that part more later. has the flow regulator now, deffently not at 9psi no more maybe 6ish i think. plugs are gapped and not black. umm dont think its runnign rich. can rev with no miss, just idles and misses then. umm temp is normal bout 190 i say, not a dummy gauge eighter, i can see it raise. but lately it seems to be running cooler, like 160ish. could be bc of the could here, but it runs at that after reaching 200 i say. umm side note i can tell when the choke cuts off, it goes from 3600rpm to 3000rpm shot idk number on the carb, its a 2bbl ffs lol. ill get it when its light out. and ya knowleadge is good, thanks for the help.

hmm on a side note, again, the is this ticking from the carb, a loud ticking, like a soliend (sp ik) would that happen to be this sensor? and to think bout it this other guy had the same problem, bad tps, but his was tpi and i thought since i had carb it wouldnt be the same...but gm still found a way to screw me over (when it comes to electriclly and f.i. in general i couldnt fight my way out of a wet paper bag)
Old 11-06-2009, 11:08 AM
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Re: carb jerking problem...help plz!

rebuild carb and put in a new float.

Those carb are great, except for the sunken float problem they all end up with.
Which a regular rebuild in a timly manner would fix but folks never do that stuff.

It will run rich and dump fuel into the oil, trashing the bearings.
Old 11-06-2009, 05:07 PM
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Re: carb jerking problem...help plz!

Originally Posted by DARKmj16
its the remote coil pack, right on top of the passenger side valve cover. and bad coil wire...? like the wire that goes from the coil pack to the cap, the same wire thats in the plug wire set? or a different wire?
as a side note if its the wire that comes with the plug wires, im throwing .45 bullets at the car from a colt double eagle...
Sorry I didn't have time to respond again this morning. I had to leave for work.

It sounds like you already changed wires so the coil wire idea can probably be ruled out. But, you mentioned that your idle is at 3000-3600 rpm? Get that fixed first. You wont be able to check timing, TPS or anything else with the engine running like that. Check to see if the previous owner turned the idle and/or fast idle screws all the way in.

Also, that clicking you hear from the carburetor is the mixture control solenoid. It's normal but, I'm surprised you could hear it over an engine running that fast.
Old 11-07-2009, 02:11 AM
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Re: carb jerking problem...help plz!

Originally Posted by Zwrench
Sorry I didn't have time to respond again this morning. I had to leave for work.

It sounds like you already changed wires so the coil wire idea can probably be ruled out. But, you mentioned that your idle is at 3000-3600 rpm? Get that fixed first. You wont be able to check timing, TPS or anything else with the engine running like that. Check to see if the previous owner turned the idle and/or fast idle screws all the way in.

Also, that clicking you hear from the carburetor is the mixture control solenoid. It's normal but, I'm surprised you could hear it over an engine running that fast.
its ok lol i went ot bed. and idk botu wires yet, i havent replaced em and if they are indeed the ones from 7 yrs ago...then wow. and we where able to get idle down but then after driving it just goes right back up, but on the start up when its cold it idles right bout after a mile down the road its up there again. and checked idle screws. and ya thats why i asked if that was normal, bc the engine at 3k rpm and hear the ticking...i was wondering is that ok.

and ya the carb rebuild is coming, new float huh? ive actually heard that once b4 but passed it off bc i thought it was getting to much fuel from the new pump. o and there is no gas or anything for that matter mixing with the oil, i check it every gas stop (weekly lol) and its not burning oil eighter.

attention another mystery! when in 4th i had the pedel top the floor to climb a slight hill on the freeway, going bout 45-50 and it started to jerk! like it does when not at open throttle! wtf!!!!!!!!! also thanks everyone for the help, havent got the carb number yet but ill get it soon.
Old 11-07-2009, 03:52 AM
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Re: carb jerking problem...help plz!

If it was me, I'd get a new carb and Distributor, and ditch the Computer....that way all you have to worry about is tuning the carb and setting the timing correctly...plus youd be able to disconnect / ignore all but 1 or 2 sensors.......you said that you have a 2 bbl carb on it now, and those can be had dirt cheap from a rebuilder or eBay, even Craigslist...Then pop on a new/used/rebuilt vac advance dist, and those are cheap too..... my car ran like $hit when I got it (Ive got a V8 but same story) It ran ok if I kept my foot to the floor, but it idled high, Ran Rich as he11, stuttered and fell on its face if I put it under load in the high RPMs, but all of that went away for less than $150..... I got a brand new carb and dist and chased down and plugged/fixed as many vac leaks as I could find and WHOA its not even the same car....My ...The CCC system works great when its Working Properly but its a biatch to fix/diagnose when its not, and there are so many variables...You could end up throwing money at "maybes" and it still doent run......just like F.I., complicated and the smallest Gremlin can have you chasing you tail until you luck up and figure out why a simple/cheap part like an O2 sensor,Ecm or whatever can make an otherwise great car act like a POS, and computer parts dont have a very long lifespan....so my advice is permanetly "Fix" the car by SIMPLIFYING IT.

And I doubt it will fix your problem but iirc, the fuel pressure for a carb needs to be at 4 or 5 psi....worth a try.
Old 11-07-2009, 10:52 AM
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Re: carb jerking problem...help plz!

Originally Posted by DARKmj16
and ya the carb rebuild is coming, new float huh? ive actually heard that once b4 but passed it off
In the s10-s15 world they are shocked when a carbed 2.8 makes it past 70,000 miles as the sunken float trashes the engine by then if carb is never serviced.

I own one now to ocuase of that, low mile around town truck, sold to a college kid after sitting around, the kid put 10 miles on it and it spun a rod bearing.
Old 11-07-2009, 02:05 PM
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Re: carb jerking problem...help plz!

Originally Posted by RedRokkit
If it was me, I'd get a new carb and Distributor, and ditch the Computer....that way all you have to worry about is tuning the carb and setting the timing correctly...plus youd be able to disconnect / ignore all but 1 or 2 sensors.......you said that you have a 2 bbl carb on it now, and those can be had dirt cheap from a rebuilder or eBay, even Craigslist...Then pop on a new/used/rebuilt vac advance dist, and those are cheap too..... my car ran like $hit when I got it (Ive got a V8 but same story) It ran ok if I kept my foot to the floor, but it idled high, Ran Rich as he11, stuttered and fell on its face if I put it under load in the high RPMs, but all of that went away for less than $150..... I got a brand new carb and dist and chased down and plugged/fixed as many vac leaks as I could find and WHOA its not even the same car....My ...The CCC system works great when its Working Properly but its a biatch to fix/diagnose when its not, and there are so many variables...You could end up throwing money at "maybes" and it still doent run......just like F.I., complicated and the smallest Gremlin can have you chasing you tail until you luck up and figure out why a simple/cheap part like an O2 sensor,Ecm or whatever can make an otherwise great car act like a POS, and computer parts dont have a very long lifespan....so my advice is permanetly "Fix" the car by SIMPLIFYING IT.

And I doubt it will fix your problem but iirc, the fuel pressure for a carb needs to be at 4 or 5 psi....worth a try.
wow your car sounds like mine is now lol. and ive got my problem solved here shortly, a v8 build! found a great deal and cant pass it up. but until then new carb and new dist. why new dist.?
also the hyness manual says 5-7 fuel psi...hmm i think ill 5 psi see wut its like.
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