Q-Jet issue. Can't fix

[jfelicia64]

Hey guys, I have a 78 c10 with a quadrajet 4BBL and I have the dreaded bogging issue. Can't find the solution but anytime I give the throttle more than 50% it feels like it's not getting enough fuel or something. Just Boggs and falls flat on its face. I've cleaned and cleaned the carb thinking it was junked up. I know all 4 "barrels" are opening but I can't figure out why it's bogging. I'm new to the c10 but not Afraid to pull the carb apart again to fix the issue. Any input is greatly appreciated! Thanks!


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[Irish_Alley]

take it you replaced all the filters?

[jfelicia64]

I've only found one filter and its the inline filter and it looks literally brand new


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[Irish_Alley]

talking about the one at the inlet of the carb right?

[enaberif]

Bogging is a sign of a qjet that is not properly setup. Either through linkages or other various means. You suggest watching videos on youtube about qjet bogging and how to fix it.. there are tons.

[Irish_Alley]

Try this
 if you scroll down you will also see how to trouble shoot this isnt for your truck
you can find yours here

[jfelicia64]

Great! Will give this all a go tomorrow morning! Thanks fellas. Will report back tomorrow


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[HAULIN IT]

A couple things can make the bog. First, Check the accelerator pump to see that as you start & continue to rotate the throttle, you get a near instant & steady squirt. Do this with the engine off of course.
The secondary air door opening too early &/or too fast is the other common cause for the bog. With the overly large sized secondaries (combined with the weight mass of a truck) it is easy to end up with a lean bog from an idle.
To check the door vacuum pull-off...remove the vacuum hose, push the linkage into the pull-off & then "cap" the vacuum nipple with your finger. If the linkage does not stay in...the pull-off is bad & needs replaced. If after you remove your finger the linkage returns to the "open" position in less than 2 seconds, it is likely too fast for a modest powered, heavy truck.
The secondary door tension can be tightened to help with this problem as well.
 Check the accelerator pump for a de-formed/split cup by checking the squirt upon throttle activation & the pull-off working properly & report back...the dreaded Q-jet bog CAN be cured! Lorne   

[jfelicia64]

Well, replaced the accelerator pump... Only $10 and probably never was replaced before. Still doing the issue. It does it no matter what gear I'm in if I got passed 50% throttle. Even if I'm in 1 or 2 manual on the column. I don't think it's the secondaries issue,  the vacuum door pull off is the same thing as the vacuum cut off? The bowl on the side of the carb?




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[HAULIN IT]

Yes that's it , Some carbs have a second one in the back with a more complex linkage. Does your's only have the one in the Right front that you posted?

[jfelicia64]

Yes, only that one. Bought a "remanned" q jet last week should be here today I'll put it on and see what the results are!


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