454 Sputtering driving down the highway and sometimes idle/in town speeds

[Steve341]

Okay, with camping season coming up around the corner I would please love some help with my pickup so I can proceed to load up the camper in the box without breaking down lol. First of all I think the truck is not getting enough fuel to the engine. The truck is a 1975 chevy scottsdale 3/4 ton camper special with a 454 engine under the hood. I have to really pump it 20 times before it even thinks of firing when cold. (Herd this is normal for GM carburated trucks) Have to hold the foot on the gas for a minute or two or else it will stall and once it warms up abit i stomp on it quickly to bring the idle down. Seems once it warms up and I tap on the gas it will almost stall at idle. Yesterday when I was driving it to go pick up about 10 sheets of plywood it stalled on me 2 or 3 times in a mile or so drive to the lumberyard. It has been sputtering going down the highway at speeds above 40 mph and have to take the foot off the gas pedal and it will start going again until I reach over 40 mph. When I floor it, the 4 barrel carburetor kicks in for about 2 seconds and the engine nearly completely dies. So I do the same thing foot off gas, and lightly resume acceleration. Is the carburetor done or dying a slow painful death? What can I do to get this thing running the way it should? Any input would be greatly appreciated. Thanks in advance

[zieg85]

Have the q-jet rebuilt, classic signs of the accelerator pump being bad, float needing replaced along with the choke pull-off probably needing replaced.  Sounds exactly how my 454 in my 1985 is acting...

[Engineer]

+1 on the Q-jet rebuild.

In addition to the aforementioned you can have a sunken float. BTDT.

[Steve341]

I do not know much about carburators. Is this easy to do? Are parts readily available?

[81_Chevy]

Is this easy to do?

if you know what your doing, its not hard

Are parts readily available?

very, you can probably get a rebuild kit at your local auto parts store. just get the # off your carb.

[454Man]

Q jet rebuild is easy plenty of youtube and books out there on it. No need to modify it just a simple rebuild. I will let everyone know cliffshighperformance.com sells a ethonal proof accell pump setup that won't deteriorate like the parts stores will.

[81_Chevy]

Q jet rebuild is easy plenty of youtube and books out there on it. No need to modify it just a simple rebuild. I will let everyone know cliffshighperformance.com sells a ethonal proof accell pump setup that won't deteriorate like the parts stores will.

they makes those?! 

[454Man]

Lol. Dem der da knew generashion parts we been awaitin fer

[81_Chevy]

hahahahahaha 

[Steve341]

I defiantly think it is a fuel problem, but I do not think there is anything wrong at all with the carburetor. The truck stalled going down the road on the weekend, and I had enough to just coast into a parking lot thank God. I could not start it, it would not even fire, and the carburetor was dry. Let it sit and cool off came back about 4 hours later with my dad, he knows abit about these trucks so I walked home got my hotrod cavalier LOL as it only broke down 2 blocks away. After letting her sit for the 4 hours came back starter spinning engine over quite fast not a fire. Pump pump carburetor is dry, no evidence of gas or scent. Proceeded to prime the carburetor manually with the jerry can, of course it starts right up and dies. Did it again but poured more gasoline into the carburetor and once it started I held my foot on the gas for oh a minute or so, and it stayed running, (quite poorly I may add) drove it back home the 2 blocks and parked it.  I love working on this pickup. What modern vehicle takes 10 seconds to replace the fuel pump on?? lol. Anyways here is an update. I replaced the fuel filter just now, there was rust colored gas coming out of it. Took a bit of work to get it started maybe 8-10 pumps. (I think it was because I had replaced the fuel filter) The truck was hesitating when the engine was cold. If I was light on the gas it would of course rev up like normal. To the floor quickly, I'd say about a half a second it would hesitate and then rev. Instead of waiting for it to reach operating temperature at idle, I decided to hold my foot on the gas at oh I'd say 2000 RPM or so. shut er off for a minute to check for leaks in and around the new fuel filter, all was fine. I'd like to mention in the past the gas would not drip out of the old filter, it would literally run out. That filter must be clogged. Anyways after I got my temp gauge to normal operating temperature I proceeded to press the accelerator pedal to the floor real fast like when the engine was cold, and guess what? No hesitation. My next step is I ordered a new fuel pump from part source in Edmonton I think it is $35, looks like about another quick job. I am not going to replace it right away, my dad says there is a filter or a screen inside the carburetor that I will check, he said to undo the gas line going into the carb remove the filter and connect the gas line again, and see what happens from there. Then well I will have the pump so may as well replace it too. I am scared to take her out for a drive and open her around the block and then if it stalls and does not start then I am in trouble. Can you guys tell me if this sounds more like a fuel delivery problem? After the new fuel filter, carburetor was not dry.

[Steve341]

Q jet rebuild is easy plenty of youtube and books out there on it. No need to modify it just a simple rebuild. I will let everyone know cliffshighperformance.com sells a ethonal proof accell pump setup that won't deteriorate like the parts stores will.

they makes those?! 

Why do they have to put that crap in the fuel?

[454Man]

To extend our resources... Idk emissions toshorten the life of our old style engines. who knows... Idk

[Steve341]

Hesitation gone in 2 barrel mode. Improving in 4 barrel mode but still there. And man does it ever go when you floor it i floored it at 30 mph and it was laying rubber. Still starving for fuel tho

[Steve341]

OK I think I finally found success. Replaced the fuel filter in the carb and go like rocket 2 barrel 4 barrel no hesitation at all. 0-60 in no time

[stenny]

I never rebuilt a carb before got the rebuild kit for a edelbrock I went through took my time at my kitchen table cleaned and replaced everything carb runs mint never had a issue except one of my floats had a Hole in it and had to be replaced do it yourself its pretty easy took me a while but that's because I wanted to make sure to do it right and clean everything car ran like new after