Carburetor acceleration pumps trouble

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boeing7873
Argentina
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Carburetor acceleration pumps trouble

Post by boeing7873 » Sun Sep 24, 2017 2:21 pm

Again back to my carbs. Truck is running rich, due to low power, stumbling, out of idle. I can't load the engine without pumping the throttle and revving it up before releasing clutch. Only way to alleviate problem is to pull out the idle screws out about 3 to 4 turns, which make other problems, like backfiring on deceleration and foul smell from exhaust.

So I started to look for carburetor acceleration pump troubles. When I look at the fuel coming out of the 01-40-32 injector tubes, some have a very smooth stream, straight down, others have like a fan type of spray. I thought maybe they had debris on them, so took a couple out and passed some thin copper wire through them. No difference.

I am starting to doubt about the linkage, I read here on the forum that manuals show diagrams with the levers set on the most outer hole on the lever, but some manual pictures showing the levers installed in the most inner... followed the diagram, not the pictures.

How about the valves? (01-40-49 and 51) Any typical failure there? Those are expensive!! I'll spend $200 just on those but before I do that... should I get a new carb?
The pumps themselves are new, just changed them with the carb kit replacement.

Something that I remember during rebuilding was some play in the linkcage arms, I will have to recheck that in the process...

Any advice on these acceleration pumps not working will be appreciated.
Jeronimo
Jerome
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audiocontr
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Re: Carburetor acceleration pumps trouble

Post by audiocontr » Sun Sep 24, 2017 7:35 pm

Does it idle fine?

Are you sure its not leaky butterfly shafts? They commonly wear out
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boeing7873
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Re: Carburetor acceleration pumps trouble

Post by boeing7873 » Sun Sep 24, 2017 10:37 pm

I have sprayed carburetor cleaning fluid on both ends without any success in changing the RPMs. Any other suggestion on how to test this?
Thanks,
Jeronimo
Jerome
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bbolander
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Re: Carburetor acceleration pumps trouble

Post by bbolander » Mon Sep 25, 2017 2:12 pm

We had a similar problem on ours, replaced the pump suction and pressure valves and the accelerator pump jets and nozzles, runs great now. Fuel was dripping from the nozzles. Probably could have purchased rebuilt carbs for not a lot more than what we spent on rebuilding ours.
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boeing7873
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Re: Carburetor acceleration pumps trouble

Post by boeing7873 » Mon Sep 25, 2017 10:51 pm

Hi Bbolander,
I did read your previous posts on the issue... like you said, paying $50 per valve... 4 of them! Might as well go with two new carbs or EFI!
I will take them apart tomorrow and check again the valves...
JC
Jerome
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boeing7873
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Re: Carburetor acceleration pumps trouble

Post by boeing7873 » Fri Nov 24, 2017 11:30 pm

Problem almost solved... changed Idle Jets from 55 to 60 (also went from no o-ring type to Oring type.)

Runs very well.. but still with 2,25 turns on the idle screws. Less and it does not like much the transition from idle to 1600 rpms.
Jerome
CRJ Driver

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