Mechanical fuel pump

[77 K20]

I have the HT383 GM crate engine. In the owner's manual they recommended a GM peformance pump that puts out 110 GPH. I've went thru 2 of them in 2 years. At $100 each I'm getting tired of it. They leak out the bolts on the bottom. I've tightened them up and it still leaks.

So I'm thinking of just putting a stock fuel pump back on it. I've never had issues with them. But I can't find flowrates... but I'm not sure what the fuel requirement even is for that engine. And to complicate things a bit more- the mechanical fuel pump is only used to fill a small underhood "fuel cell" that has a high pressure electrical pump in it for my fuel injection.

Before I screwed with everything the truck has a 3 line pump. Now I'm using a 2 line pump. Not possible to go back to 3 line.

Looking on RockAuto I see there are a few types of 2 line pumps:

Delphi:
MF001
MF0062
MF0057

What is the difference with those? Any of them work? Flow rates on them the same?

 

[fussfeld]

If you're just using the mechanical pump to supply/feed the sump then you don't need a high flow pump. ( i wouldn't think so, at least?) A stock pump that puts out 2-4lbs of pressure should be good enough?

 

[74 Shortbed]

Don't need no high performance pump to feed a surge tank since all returns goes back to that tank, stock pump is plenty adequate to keep that tank full.

 

[77 K20]

Ok- there isn't a whole lot of volume in that fuel sump but since the engine has a mild cam it probably wouldn't need much. I finally did find that a Carter M6624 is rated to free flow at 40 GPH. They are made in South Korea. Better than China I guess.

The way my luck has been going with vehicles lately I thought a stock pump might not keep up with the electric pump and would then go lean or burn up the electric pump.

Nowhere can I find what the threaded size of the outlet is.

 

[74 Shortbed]

The return lines go back to the small tank so it's not being drained, and the electric pump is putting out pressure not huge amounts of volume, all the mechanical is doing is keeping the tank full, a factory stock pump is all that's needed..

 

[77 K20]

I did find a calculation for fuel pump volume.

(max HP x BSFC)/6

BSFC is typically 0.5 for a non-aspirated engine.

(330x0.6)/6= only 27.5 GPH.

So stock fuel pump will be enough. And it will be nice to have reliability again.

 

[77 K20]

And I finally found the threaded fitting size. It is NOT a NPT fitting like my existing fuel pump.

Supposedly is it an inverted flare fitting. 5/8"-18.

This fits the hard metal line that goes from the fuel pump to the carb (at least back in the day from the factory).

I ordered a 5/8" inverted flare to 3/8" hose barb fitting. Edelmann 821660.

Figure this information might be good for future searches.

 

[74 Shortbed]

Sounds like you're good to go.