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08-25-2022, 12:23 PM | #1 |
Registered User
Join Date: Jul 2019
Location: Calgary, Alberta
Posts: 81
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Stupid Mechanical Fuel Pump!
I bought the 385 horse SBC carbureted engine from the Chevy Performance catalog a few years ago. It has generally run well. But last week it quit on me with no warning. Figured out it was the fuel pump. Had a heck of a time getting the pump out because the bolt was blocked by some funny-looking little shiny metal rod. Once I finally got it out I realized the rod was a pin that was supposed to hold the pump lever in place. It had slid right out of it's slot. The pin is just friction fit into a hole in the pump! Without that pin, the pump instantly stops pumping. What a stupid design! I got a new aftermarket pump and the rod is firmly held in place. Much better design.
Now I'm ready for the weekend road trip! Have any of you had this problem before? |
08-26-2022, 02:47 AM | #2 |
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Join Date: Nov 2010
Location: calgary alberta
Posts: 8,342
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Re: Stupid Mechanical Fuel Pump!
i have had many sbc engines but the biggest issue I have had is a hole in the pump diaphragm which causes fuel to be sprayed down the side of the engine block (nice clean engine after) and also dilutes the oil. usually happens in some small town where the parts guy has you over a barrel. anyway, to answer the question, nope. never had that problem ever. just got a bad pump I guess.
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08-26-2022, 09:51 AM | #3 |
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Join Date: Oct 2013
Location: Maine
Posts: 2,376
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Re: Stupid Mechanical Fuel Pump!
Did that fuel pump come with the engine? A new age AC Delco?
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08-27-2022, 07:12 PM | #4 |
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Join Date: Dec 2017
Location: Elkhart, Texas
Posts: 1,853
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Re: Stupid Mechanical Fuel Pump!
Most manufacturers' fuel pumps have used that design for years.. The water pumps used in the pioneer days used that design.. The lever is moved up and down from some force.. The pin is a pivot point for the lever.. It should be made from a hard non-wearing metal. In the GM design, that lever is powered by an eccentric on the camshaft and a rod linking the two. It's not a bad design at all. The most common failure is the one mentioned by dsraven, the diaphragm fails..
I've been doing this car stuff for about 60 years, 35 of 'em on a professional level as a paid mechanic. I've seen a few failures like that, but most of them occurred recently. Your issue isn't a design flaw at all.. It's the cheap material being used in today's cheaply made chinese made products.. |
08-29-2022, 11:05 AM | #5 |
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Join Date: Jul 2019
Location: Calgary, Alberta
Posts: 81
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Re: Stupid Mechanical Fuel Pump!
Yes, it came with the engine from the Chevy Performance Catalog. It was brand new (probably remanufactured). Not sure where it was made, but supposedly it was OEM. The pin was not adequately held in place so it just slid out. The new pump performed great on the six hour drive yesterday. Because it has a slightly different design, I am not concerned about the pin falling out. Now I just have to fret about the diaphragm failing. Always something to worry about...
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08-29-2022, 08:59 PM | #6 |
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Join Date: Jan 2013
Location: Eastern TN
Posts: 1,921
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Re: Stupid Mechanical Fuel Pump!
Delco quality has sucked for years. Gm just license there name to companies like Proform to make obsolete parts. Case in point, about 10 years ago I payed extra for a Delco 3 bolt SBC starter. The nose was misnachined and you could only install 2 bolts. Gm does not care about quality for this older stuff. Long story short. You got a crap quality fuel pump. As noted before, the failure should have been the diaphragm. OE was probably a carter pump but they sold out years ago. Best bet is go to a part store and look at a few and settle on the one that looks the best for construction. No sense going broke on a holley pump that will probably also require a regulator.
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