carb issue?

[Rifter_Chevy]

My truck has a strange issue.

Its a 84 3/4 ton camper special SB 350 with a turbo 400 behind it, has stock rochester carb on it which i was told was just rebuilt when i bought it 6 months ago.

My issue is when i stomp on the pedal from a stop like REALLY stomp on it and depress it really fast it stalls, like just instantly dies, no sputter no beginning to pull and dieing just straight up dies, literally like i flipped the kill switch to the ignition fast. But if i press the pedal slower, like taking a full half second to fully depress it it never stalls, only when i really hit it.

Also VERY rarely when i stomp on it while already moving it will bog out at wide open throttle, this is very rare though maybe does this 2 or 3 out of every 50 times i stomp on it while moving.

Also when i start it from cold i need to help it idle for the first 10-15 seconds or it will sputter out and die but this has been normal in my experiance with alot of carbed vehicles but thought i would mention it.

Any reccomendations before i just say screw it and go buy a edlebrock 650 with a performer intake

[Goldfinger]

My Rochester did this because over time the fuel filter clogged and i neglected to change it. it could only get enough gas for regular driving. After 25 years i replaced my carb with a 1406 600cfm edelbrock carb. After i got it hooked up i never had the problem again. Also putting a new carb on an old engine and tuning it properly can return to stock or better mileage.

[njlimbaugh]

Check your ignition timing before you do anything with the carb. It sounds like the ignition is retarded. Try advancing it a little. Easy enough to check before you jump into anything that will cost money!

[geezer#99]

With your engine shut off look inside the carb and when you stroke the throttle you should see 2 good streams of fuel shoot into the carb. If there's none then your accelerator pumps not working.

[DetroitDan]

x2, accelerator pump and timing.

I just had my q-jet rebuilt, now I have an issue when I stomp the gas. It doesn't bog or cut out at all, but what happens is somehow the carburetor way up front is causing traction issues in the back. It's actually quite easy to defeat traction now, but it seems to be running good so I'm going to leave it alone. ;>

[rayfinseats]

If it's a big old heavy pig with 273 gears that sounds pretty normal. Try setting the secondary throttle adjustment a little tighter.

[Rifter_Chevy]

fuel filter is brand new, changed it a few weeks ago, old one was clean though so i dont think that was the issue. Also the fuel pump is only 2 months old so thats probably not it either, also replaced all rubber lines and pressure tested the fuel pump.

Will check timing tommorow i have a buddy with a timing light. But it does pull hard when it doesnt bog out, can lay 20 feet of rubber no problem even with my large meaty mud terrain tires if i two foot it and bring the revs up for a good launch so i cant see the timing being that retarded.

it is a big old heavy pig but with 3.73 gears not 2.73, i cant imagine having 2.73 gears i think i would shoot myself.

Thanks alot for all the suggestions guys! I will let you guys know for sure when i fix it.

[Rifter_Chevy]

Its running 14 at the crank, thats not to much timing is it?

[geezer#99]

If that's with the vacuum hose plugged then it's close. Maybe 12 would be better. Might ping at 14.

[jimboh247]

Not meaning to jack your thread, but I'm going thru the same sort of issue. How did you pressure test your fuel pump?

[Rifter_Chevy]

Originally Posted by jimboh247

Not meaning to jack your thread, but I'm going thru the same sort of issue. How did you pressure test your fuel pump?

I have a friend with a pressure tester, i hooked it up with a T connector it came with to the pump output and then to the carb.