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GMC V6 and V12 Engines Engine repair and rebuilding

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  #1  
Old January 29th, 2022, 06:16 PM
billez billez is offline
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Default Fuel Pump

I was wondering if the group had an option on mechanical or electric fuel pump? It appears that most places try to switch to electric.
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  #2  
Old January 29th, 2022, 06:53 PM
kknotts kknotts is offline
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Default Re: Fuel Pump

I have been a stubborn disciple of staying completely original but after four mechanical pump failures over roughly ten years I bit the bullet and installed an electrical. Man! What took me long!! Fast easy start ups and a smooth running happy truck.
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  #3  
Old January 29th, 2022, 07:59 PM
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Funky61 Funky61 is offline
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Default Re: Fuel Pump

I got this mechanical off Amazon for one truck.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I also have a Carter electric on my suburban I installed years ago that still is working.
I have a Holley two barrel on that one and the recommended psi is 5-7
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Old January 29th, 2022, 08:15 PM
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Default Re: Fuel Pump

Quote:
Originally Posted by kknotts View Post
I have been a stubborn disciple of staying completely original but after four mechanical pump failures over roughly ten years I bit the bullet and installed an electrical. Man! What took me long!! Fast easy start ups and a smooth running happy truck.
I like them both, so what I do is keep the original mechanical pump and install an electric pump as a backup. It saved my bacon one time when I was in heavy interstate traffic and my engine died. Thank goodness I had the presence of mind to reach down a flip the electric pump switch since I was in the fast lane at the time.

Electric pumps are also helpful for priming the float bowl in trucks that are not driven often.
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Old January 29th, 2022, 08:43 PM
lizziemeister'sV6 lizziemeister'sV6 is offline
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Default Re: Fuel Pump

How do you get around the restriction of the electric pump in the fuel line leading from the tank to the mechanical pump? Do you have a by-pass for the electric pump when using the original? Guess I would be hesitant on running the electric pump if the original pump's diaphram is ruptured? Yes, that's 3 questions.

Last edited by lizziemeister'sV6; January 29th, 2022 at 08:46 PM. Reason: left out something.
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Old January 29th, 2022, 11:26 PM
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Default Re: Fuel Pump

I had read online and other websites that if you had an electric fuel pump connected to a mechanical and the diaphragm were to rupture, you would be sending fuel into your crankcase. That is the reason I did not connect them in line.
I know the mechanicals are prone to failure and there was discussion here as to why that might be; old stock sitting too long on the shelf, or the ethanol eating away the diaphragm etc.

Im curious too Ed how yours is set up
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Old January 30th, 2022, 01:02 AM
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Default Re: Fuel Pump

Quote:
Originally Posted by Funky61 View Post
I had read online and other websites that if you had an electric fuel pump connected to a mechanical and the diaphragm were to rupture, you would be sending fuel into your crankcase. That is the reason I did not connect them in line.
I know the mechanicals are prone to failure and there was discussion here as to why that might be; old stock sitting too long on the shelf, or the ethanol eating away the diaphragm etc.

Im curious too Ed how yours is set up
Mine are inline. The electric is bolted to the frame down below the mechanical one. When my mechanical failed and I drove home on the electrical pump, I changed the oil along with installing a new mechanical pump. Evidently no harm was done. The engine still runs fine 20 years later.

If you're running an electric pump only, you definitely want to bypass the mechanical pump.
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  #8  
Old January 30th, 2022, 03:13 AM
kknotts kknotts is offline
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Default Re: Fuel Pump

I had a block off plate fabricated for where the mechanical mounted and removed it completely. No need for it to be robbing power and causing unnecessary friction. Installed the electrical in cab in front of the tank. 2 to 5 psi for the original stromberg. Simple wiring and plumbing after that.
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  #9  
Old January 30th, 2022, 04:36 AM
billez billez is offline
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Default Re: Fuel Pump

Thanks for all the replies. I usually try and keep things pretty original thats why I asked. Most non 305 people just say block off the mechanical pump and put in an electric. I have a 68 c30 with a Rochester carb and it has been a bit of a pain with getting the mechanical replacement. None of the local auto parts store list one that fits . I did finally find one on rock auto. That appears to be the right one. Its not one listed even for the 305 v6 I came across a number on the pump under 40275 which equals a Carter M60577. Might as well ask is the Carter any good? Thanks again
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Old January 31st, 2022, 05:57 PM
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ilvracn ilvracn is offline
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Default Re: Fuel Pump

after my second fuel pump failure in a few thousand miles, i took the pump apart. it looks to me like the check valves are not staked in and fall out, the diaphram looked fine. i carry an electric pump for backup. i have a new mechanical one also, i think i'm going to take it apart and put some stake marks in the housing around the check valves. if it goes bad again, hopefully the next one is better. i also use only non ethanol gas in this truck. that should help with the life of the diaphram.
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