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chuxcar
User
Feb 2, 2012, 5:30 PM
Post #1 of 8
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bucking as you drive
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1985 Chevy S-10 w/2.8L V-6, manual trans. 125K miles original. Truck is hard to start when cold, won't idle for about 5 minutes, and bucks when you try to take off and up hills. This bucking is severe as if the ignition were intermittent or the fuel supply is restricted.
The coil, distributor module, cap and rotor, the spark plugs, fuel pump, fuel filter have all been replaced in the last six months. The plug wires have been visually inspected and are in good shape.
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 2, 2012, 6:00 PM
Post #2 of 8
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Re: bucking as you drive
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You would have to hook up a fuel pressure gauge and monitor it through the period when you have to problem to see if the pressure is dropping when this occurs.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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chuxcar
User
Feb 3, 2012, 9:24 AM
Post #3 of 8
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Re: bucking as you drive
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Where does the fuel pressure gauge hook up at on my truck?
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Discretesignals
Ultimate Carjunky
/ Moderator
Feb 3, 2012, 10:04 AM
Post #4 of 8
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Re: bucking as you drive
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It would have to be T'd inline between the carburetor and fuel pump. Fuel pressure should be around 4-6.5 psi
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
(This post was edited by Discretesignals on Feb 3, 2012, 10:07 AM)
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Hammer Time
Ultimate Carjunky
/ Moderator
Feb 3, 2012, 2:11 PM
Post #5 of 8
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Re: bucking as you drive
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I thought this was TBI. If it's a carb, that would change things somewhat. It likely have some carburetor and/or choke issues.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
Feb 3, 2012, 3:14 PM
Post #6 of 8
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Re: bucking as you drive
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Not sure ( a maybe of even mid year changes?) but think this was first year for TBI (fuel injected) if not those carbs were a real pest to get right adjustment on and would have a mechanical fuel pump on side of engine,
T
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chuxcar
User
Feb 8, 2012, 9:32 PM
Post #7 of 8
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Re: bucking as you drive
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It's definitely a carb.
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Tom Greenleaf
Ultimate Carjunky
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Feb 8, 2012, 9:49 PM
Post #8 of 8
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Re: bucking as you drive
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Owned that last 2V carb and what a pest. Check all the zillion vacuum hoses and the choke pull-offs. If I recall the front one is mandatory or it will run like crap if leaking and you could at the age just do without the back one. That and electric choke heater must heat. Just with key to run, ignition off you can feel it warm up by hand or watch it with air cleaner off + just plug off vac hoses to it for a test.
Inside air cleaner is a thermal vacuum switch when it senses air temp rise will open the carb some more via the rear pull-off.
Not sure how easy parts if needed will be to find. Do anything not to break engine temp sensing vacuum trees if hose are bad as you plain won't glue one up and they will be brittle so if a hose is bad carefully cut it and peel it off.
My bet is that carb and vacuum leaks so far,
T
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