Author Topic: 350 with quadrajet wont climb a grade  (Read 5002 times)

Offline 88rxna

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350 with quadrajet wont climb a grade
« on: October 14, 2019, 09:23:37 PM »
The other day my 84 c10 with a jegs 350 almost died as i was climbing a grade. I had to feather the gas to make it the rest of the way.
Now its having trouble staying running. Sometimes it'll idle fine, other times it may stall. Sometimes it'll fire right back up, other times i need to use starting fluid and itll idle fine after it starts. Heres a list of things of tried:

Changed fuel pump and filter
Checked vacuum advance with a vacuum pump, fully opened at 12psi and held open for 5 minutes
Checked cap and cleaned contacts
Checked wires for distributor
Checked plug wires at night for arcing

Im really not sure what else to look for as im prettt new to carbs? Any other ideas?


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1984 custom deluxe C10
4.8 sloppy stage 2 cam with springs
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Offline 88rxna

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Re: 350 with quadrajet wont climb a grade
« Reply #1 on: October 14, 2019, 09:27:49 PM »
Here's a few pictures of the carb

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Offline Stewart G Griffin

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Re: 350 with quadrajet wont climb a grade
« Reply #2 on: October 14, 2019, 10:02:35 PM »
The first problem is uremco.....    Do you still have the original carb?

i would want to check the float level first.

Offline VileZambonie

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Re: 350 with quadrajet wont climb a grade
« Reply #3 on: October 15, 2019, 04:24:45 AM »
Did you check you fuel level?
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Offline 88rxna

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Re: 350 with quadrajet wont climb a grade
« Reply #4 on: October 15, 2019, 06:52:38 AM »
I filled up with 93 the day before.
Unfortunately i do not have another carb to try.


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1984 custom deluxe C10
4.8 sloppy stage 2 cam with springs
s480
xmax terminator
4l80E

Offline 88rxna

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Re: 350 with quadrajet wont climb a grade
« Reply #5 on: October 15, 2019, 10:11:41 AM »
Heres a plug...
But i did find that the rotor wires to the cap wouldnt clip onto the cap correctly (clip is loose).  I zip tied it on for now and itll drive decent but and sometimes i can even give more than 1/4 throttle..
But itll still stall out and wint start unless i give it starting fluid.

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Offline JohnnyPopper

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Re: 350 with quadrajet wont climb a grade
« Reply #6 on: October 15, 2019, 01:30:05 PM »
Looks pretty lean.

You said 'filter'. Did you check the one at the carb intake or just the inline?
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline 88rxna

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Re: 350 with quadrajet wont climb a grade
« Reply #7 on: October 15, 2019, 01:49:54 PM »
I changed out the fuel filter on the carb it does not have an inline fuel filter.

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1984 custom deluxe C10
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s480
xmax terminator
4l80E

Offline bd

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Re: 350 with quadrajet wont climb a grade
« Reply #8 on: October 16, 2019, 12:22:42 PM »
Measure fuel pump draw (>20" Hg), pressure (5-7 PSI) and delivery (1+ qt within 30 seconds of cranking).  Transfer the fuel into a clear container.  Is the fuel sample cloudy or does it separate into layers after sitting for a minute?  Check the spark from a plug wire disconnected from an easily accessible spark plug.  Will the spark jump a 3/4" air gap?  Is the spark blue?
Rich
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In other words... if people learn by making mistakes, by now I should know just about everything!!!
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Offline bd

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Re: 350 with quadrajet wont climb a grade
« Reply #9 on: October 16, 2019, 01:14:47 PM »
Does the vehicle have single or dual fuel tanks?  Check the condition of the rubber fuel hoses all the way back to the tank(s).  Make sure none are stiff, cracked, or pinched.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline DanMcG

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Re: 350 with quadrajet wont climb a grade
« Reply #10 on: October 17, 2019, 04:33:58 AM »
In your pic with the "Rochester Quadrajet" in it, Is that fuel on the gasket? could it be leaking or causing a vacuum leak?

Offline FlatBlack77

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Re: 350 with quadrajet wont climb a grade
« Reply #11 on: October 17, 2019, 10:49:59 AM »
Is there a mounting bolt missing in the first pic? What is that hole for?

Is the timing set properly? Perhaps the distributor slipped.
« Last Edit: October 17, 2019, 12:11:45 PM by FlatBlack77 »
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Offline JohnnyPopper

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Re: 350 with quadrajet wont climb a grade
« Reply #12 on: October 17, 2019, 06:49:15 PM »
Saying you had to feather to get her up the hill sounds like you had enough fuel entering the bowl, so you could keep momentum by deploying accelerator pump as extra, richer source of fuel. Was that a run-on sentence?  ::)

I think you have gunk in the carb and or clogged jets/metering rods, etc.

Get her running and spray carb cleaner into the bowl vent, the center tube just ahead of the primaries (little barrels). It's about 3/8" diameter.

You will probably start to flood if you don't gas it, so gas it while spraying into the vent. Your float bowl will regulate the level for the most part.

Doing this will clean the internal passages where gas flows.

If that does not do it, pull the top off the carb  (not that intimidating) and look for gunk in the bowl and the inlet where the needle seats. Could be a chunk of rust or other debris.



Next, looking down the barrel of the primaries, you will see little opening ahead of the venturies, (round tubes suspended in the middle of the barrel) Get the red tube of the cleaner to blow those out. You will know it if they're clogged.

1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline 88rxna

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Re: 350 with quadrajet wont climb a grade
« Reply #13 on: October 18, 2019, 12:45:14 PM »
Thank you all for the suggestions..i really appreciate them.
I ended up having a rebuild kit sent to me and will tackle it this weekend. The carb is pretty bad on the outside so i can only imagine what the inside will be like.
Before i tear into it i will try your suggestions johnnypopper.

When i last messed with it, it would start right up and idle for about 5 or 10 minutes then run out of fuel and stall. If i would let it set for 5 minutes it would fire right back up and repeat the same thing.

When id first start it i could rev it pretty good without a hiccup, afyer a few minutes, not so much...then it would just die.
I opened the gas cap ( when it would start ti stall) hoping it was a vacuum issue but it did not make a difference.

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4.8 sloppy stage 2 cam with springs
s480
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4l80E

Offline 75gmck25

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Re: 350 with quadrajet wont climb a grade
« Reply #14 on: October 19, 2019, 06:04:09 AM »
You might also want to find a copy of the Cliff Ruggles Quadrajet book.  Its organization can be a little confusing if you are new to Quadrajets, since it has descriptions for all years and models, but it has all the information you need to make a basic rebuild go more smoothly.  I know Amazon sells it, and it might even be in a local library.

Bruce