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Author Topic: '78 Suburban 'chugging' on long grades  (Read 4820 times)

Offline Cliff Ruggles

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Re: '78 Suburban 'chugging' on long grades
« Reply #30 on: August 09, 2020, 08:23:19 AM »
PS:  HIC was not used on that carburetor number.

The idle vent valves weren't used either and neither one is needed for what you are doing......
« Last Edit: August 10, 2020, 03:58:32 PM by Cliff Ruggles »
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Offline RyanAK

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Re: '78 Suburban 'chugging' on long grades
« Reply #31 on: August 09, 2020, 08:42:31 AM »
Awesome. Thank you to everyone. I
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Offline RyanAK

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Re: '78 Suburban 'chugging' on long grades
« Reply #32 on: August 09, 2020, 08:43:30 AM »
Awesome. Thank you to everyone. I'll get to the cam and APT screw soon. Good to know that I'm good to go. Jets, rods, hanger look good?

I'm supremely impressed with the quality of knowledge here. Both carbs and general engine.  I think I'll stick around! :)
« Last Edit: August 09, 2020, 08:51:28 AM by RyanAK »
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Offline Cliff Ruggles

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Re: '78 Suburban 'chugging' on long grades
« Reply #33 on: August 10, 2020, 04:00:42 PM »
Cool!  8)

Lots of good knowledge on this Forum for sure. 

I encourage others respond and help out as well, some folks who are members here have extensive experience with these things and a lot to share.  One of my main goals here is to make sure folks get a good end result with these things. 

It's also nice when we sell a few parts along the way, helps keep my bills paid and the wife happy!......
« Last Edit: August 10, 2020, 04:04:07 PM by Cliff Ruggles »
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Offline RyanAK

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Re: '78 Suburban 'chugging' on long grades
« Reply #34 on: August 10, 2020, 04:38:23 PM »
Totally agree. This place is great. I've been reading other threads and the knowledge is broad. I can't imagine running anything other than a Quadrajet now. Well... unless I eventually do that 4-banger Model A traditional hot rod I've been thinking about...

I may order ahead so that I have good parts on hand in the future. Rebuild kits, rods, jets, etc. You know... just in case!
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Offline RyanAK

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Re: '78 Suburban 'chugging' on long grades
« Reply #35 on: August 20, 2020, 02:50:33 PM »
As way of an update...truck is running well down the highway. No fuel starvation issues. Can't believe it was a bonked out new fuel pump!

New issue though... when the truck is at operating temp and idling - whether in Park or in gear - the engine will occasionally stumble hard and then recover. Idle in P is ~900RPM and it'll stumble down to under 500 and then come back. In gear were around 700 and it'll stumble to almost stalling out before smoothing back out.

I popped the air cleaner so I could watch. I can see the fuel level increase in the bowl by looking down the secondary rods. Up it comes...stumble... down it goes... smooths back out. Does it just once occasionally, or it'll start cycling like this every 20 seconds.

I have a video but can't seem to post.

Float is set at 15/32. New pump is pushing ~8psi. Non-check-valve filter. Zero issues while driving.

Thoughts?
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Offline RyanAK

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Re: '78 Suburban 'chugging' on long grades
« Reply #36 on: August 22, 2020, 10:50:46 AM »
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Offline Cliff Ruggles

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Re: '78 Suburban 'chugging' on long grades
« Reply #37 on: August 24, 2020, 04:02:14 AM »
Flooding.

Haven't ran into one doing what yours is but for some reason it's having fuel control issues. 

It will be float, N/S, fuel pump/pressure related....
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