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I-6 Engines For GMCs that came with the Inline 6 Engines

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  #11  
Old June 1st, 2020, 12:59 AM
Kerzy Kerzy is offline
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Default Re: Engine dies under load.

So I added the new fuel pump and distributer which made no difference.
I sprayed some ether around the intake/exhaust manifold and the engine idle did speed up. Could a leaky manifold cause it to die under load like it is?
I thought it was a bad fuel pump which it wasn’t then I thought the vacuum advance wasn’t performing on the old stock dizzy so I replaced the whole dizzy which didn’t make a difference. I took the carb apart again and went through the instructions which I’m 99.9% sure it’s put together properly.
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  #12  
Old June 1st, 2020, 01:19 AM
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Default Re: Engine dies under load.

Quote:
Originally Posted by Kerzy View Post
So I added the new fuel pump and distributer which made no difference.
I sprayed some ether around the intake/exhaust manifold and the engine idle did speed up. Could a leaky manifold cause it to die under load like it is?
I thought it was a bad fuel pump which it wasnít then I thought the vacuum advance wasnít performing on the old stock dizzy so I replaced the whole dizzy which didnít make a difference. I took the carb apart again and went through the instructions which Iím 99.9% sure itís put together properly.

Did you remember to prime the line after installing the fuel pump? If you don't prime it it'll just suck air.
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  #13  
Old June 1st, 2020, 08:03 PM
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Default Re: Engine dies under load.

With all due respect, I have never had to prime a fuel pump.
Kerzy, is all this latest data you gave us running off of a jerry can? Does it start without squirting can into carb? Are you driving it with jerry can? What exactly is it doing now?
What you did with ether is a sign of a vacuum leak. Identify exactly where it is leaking by using a hose on the ether stem to keep the spray controlled. The Rochester carb bodies can warp. Do you have a Model B? Did you take carb completely apart, including power piston? Did you get the right b a l l s in the right place?
I can advise further if I get these answers.

Last edited by AZKen; June 1st, 2020 at 08:17 PM.
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  #14  
Old June 2nd, 2020, 12:31 AM
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Default Re: Engine dies under load.

Quote:
Originally Posted by AZKen View Post
With all due respect, I have never had to prime a fuel pump.
Kerzy, is all this latest data you gave us running off of a jerry can? Does it start without squirting can into carb? Are you driving it with jerry can? What exactly is it doing now?
What you did with ether is a sign of a vacuum leak. Identify exactly where it is leaking by using a hose on the ether stem to keep the spray controlled. The Rochester carb bodies can warp. Do you have a Model B? Did you take carb completely apart, including power piston? Did you get the right b a l l s in the right place?
I can advise further if I get these answers.
Me either, until this truck. If I didn't prime it after changing the pump I couldn't get her running. Then once primed, she ran great. Just my 2 cents. Your mileage may vary.
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  #15  
Old June 2nd, 2020, 05:33 AM
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Default Re: Engine dies under load.

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  #16  
Old June 2nd, 2020, 04:56 PM
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Default Re: Engine dies under load.

Yes, I’m currently running off a Jerry can because the factory tank is getting cleaned.
The truck starts now if I choke it, no need to put gas down the carb, but it will still stall if you hit the gas, I need to feather it slowly to increase the rpm in order to drive it; then when I let out the clutch I will want to die so I need to feather it some more. Sometimes it does stall. If I hit the gas hard you can hear air and then it will want to stall.

I removed the power piston in the Rochester B carb, cleaned it up, installed the new return spring and check ball and small spring. It did move freely by hand but maybe it’s getting stuck somehow? I’m very sure I put all the correct check !Bork!!Bork!!Bork!!Bork!!Bork! in the right places. I followed mike carb parts rebuild video on YouTube as well as the print out sheet from his web site.

With the new fuel pump and dizzy the truck is running better and will idle very nice but it is still not running “right”

I’m sitting at 8į timing with the dwell at 30. Plugs are gapped properly.

I will spray some ether to see if I can determine if/where the leak is coming from.
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  #17  
Old June 2nd, 2020, 09:24 PM
James James is offline
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Default Re: Engine dies under load.

With you feathering the throttle it sound like the accelerator pump not pumping fuel into the carb throat. Look down into the carb (with the engine not running) and work the throttle. You should see fuel squirting in each barrels. If not that why it is stalling or if it is getting fuel it might need more fuel. Just my though.
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  #18  
Old June 2nd, 2020, 09:46 PM
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Default Re: Engine dies under load.

I am now leaning AWAY from fuel delivery. Every thing sounds so right. Carb check several times. New pump tested. Not running off tank or lines. New filter.
I would:
1. Get a new condenser. 50% or more are bad right out of the box.
2. Set the points more carefully.
3. Retest motor
No result? Try 4 deg to 12 deg timing, in intervals.

Still no result? Try a coil.

These can all be tested, but the prices are low and it's easy to replace these things.

Be sure all vacuum hoses, fittings, clamps and ports are not leaking. Take off all rubber hoses and check them for cracks and holes in good light. Also there are several gasket in the kit for carb mounting flange. Double check correct gasket and that it is oriented correctly. (slots/holes)

MORE QUESTIONS: Did this start happen when running off the tank and still did it after switching to jerry can? When did this start happening? Out of the blue or after work being done? If there was work done, what was it exactly? Do you understand float level AND float drop measurements? These are BOTH VERY important with your issue.
It is pretty common that a B carb can be warped and will suck air. It takes an expert to "fix" that. After all the above fails, next time you have carb apart, set the sections on a flat surface and make sure there is to wobble and no space between carb surface and flat surface. Glass is a good test surface.

Last edited by AZKen; June 2nd, 2020 at 10:10 PM.
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  #19  
Old June 2nd, 2020, 10:06 PM
Kerzy Kerzy is offline
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Default Re: Engine dies under load.

Itís my grand fathers truck, was sitting in the barn for 20plus years. I just decided to get it running again. Been running off the Jerry can since I started to play around with it. I measured the float level as per the carb rebuild instruction sheet but Iíll check it again.
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  #20  
Old June 2nd, 2020, 10:15 PM
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Default Re: Engine dies under load.

Jerry can must have a breather hole or open top. Try a new batch of fresh gas. Make sure the hose you are using is genuine gas hose, not something laying around. Do the other stuff I mentioned. Just to repeat: there is "float level". There also "float drop". Do you understand what that is? Carb upside down with float hanging down and take measurement. You have to get them both right. Make sure you are reading the paper gauge correctly. What is your experience with motors and carbs?

Last edited by AZKen; June 2nd, 2020 at 10:22 PM.
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