acceleration problem

[JLANDRUM]

I have a 82 GMC w/350 edlebrock intake and edlebrock 4 barrel carb. Sometimes when I give it gas, I can hear the engine getting louder and getting more gas, but the truck doesnt accelerate. It feels like its bogged down and my already horrible gas milage, gets worse. I have tweaked the carb every way imaginable, I havent completely ruled it out, but I would like to see what other people suggest I take a look at. So Im open to ideas.

Thanks

[magnethead]

What transmission? Might it be slipping?

[JLANDRUM]

I just have the stock auto transmission. I never thought of the transmission because it never gives me any noticable trouble, but Ill have to look into it. Thanks for the feedback.

[EDOUBLE33]

I Would Start My Checking My Fuel Filter, I Think Many People Will Agree. I Usually Say If You Can Not Remember The Last Time It Was Replaced That Means It Is Time To Replace It.

[EDOUBLE33]

Usually What Happens Truck Runs Okay Till You Try To Accell, When You Accell The Card Is Trying To Pull More Fuel And If The Filter Is Restricted Than It Feels Like It Is Bogging Down. My 87 Did This But Thanks To Computers It Would Turn The Check Engine Light On.

[JLANDRUM]

I replaced the fuel filter last week. The problem is very intermittent. Sometimes it will go for a week or so without doing it, other times it does it everytime I start the truck. Ive been chasing this problem for months now and its driving me crazy. I took it to the shop and they couldnt recreate the problem while they had it. I was thinking maybe a vacuum line?

[grinch4om]

not likely a vacuum line, usually that would act up all the time. Is it cold when it does it or at operating temp? Might be timing, by this I mean your mechanical or vacuum advance in the distributor. Check under the rotor, make sure the weights are free and not stuck. Next check the vacuum advance by applying vacuum to the nipple, preferably with a hand pump, then relaese the vacuum and make sure the advance mechanism returns to original spot. Also total timing usually in in by 2800-3000 rpm,(unless computer controlled, then just check under the rotor)

[bmartin9122]

Originally Posted by grinch4om

not likely a vacuum line, usually that would act up all the time. Is it cold when it does it or at operating temp? Might be timing, by this I mean your mechanical or vacuum advance in the distributor. Check under the rotor, make sure the weights are free and not stuck. Next check the vacuum advance by applying vacuum to the nipple, preferably with a hand pump, then relaese the vacuum and make sure the advance mechanism returns to original spot. Also total timing usually in in by 2800-3000 rpm,(unless computer controlled, then just check under the rotor)

I am starting to think the same thing. If you have intermittent (probably you), poor, or non-existent vacuum then your truck will not behave properly since it will not be able to advance the spark in response to your throttle input. A cracked vacuum line - though not visibly breached - could cause the intermittent behaviour.

Do you see alot of black smoke pouring out of the tail pipe when you mash the go pedal?

Good Luck!

-Bryan

[JLANDRUM]

Thanks for the advise Grinch and bmartin.

To answer the questions, it usually runs better when its colder. Never gets too cold here in Houston, but I find that when it acts up, its usually in the afternoon after work when its the hottest part of the day.

No smoke comes out of the pipes when I accelerate, but thats when I feel the loss of compression/ flooding feeling.

One of my problems is that I cant get anyone to take a look at it cause I never know when its going to act up. Anyway, thanks so much for all the info, I have something to play around with now. Ill let yall know how it worked out.

[grinch4om]

next time it does it, pull over if you can,dont touch the gas pedal, pull air cleaner lid and see what position the choke plate is in. If it is closed or partially closed, that would cause what you are desribing, also if the plate is wide open, see if the carb is running over-float or pressure problem

[JLANDRUM]

Thanks Grinch.

In the senerio you are describing what would be the fix? Rebuild the carb?

Thanks

[grinch4om]

if it's the choke plate, adjust it, refer to a manual(electric choke could not have power to it or element burnt out) if it is running over with fuel, check the float , adjust or replace. what is your fuel pressure? mechanical pump or electric?

[JLANDRUM]

I dont know what my fuel pressure is, but its a mechanical pump not electric.

[grinch4om]

ok, should be ok pressure wise, try what I mentioned the next time the truck does it. If the choke plate is open all the way, and it is not running over with fuel, grab the throttle and pump it while looking down carb,(not running of course) to see it the accelerator pump is working, you should see 2 streams of fuel in the throats if it is working, if not, either the accelerator pump is bad or you havea fuel delivery problem

[JLANDRUM]

Ill try that. Thanks for all the help.