fuel pump with two nipples - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**MikeB** · 05-05-2015, 08:33 AM

An AC-Delco #41216 fuel pump for a 1982 C10 with 350 engine has two hose nipples. What is the smaller one for?

**hatzie** · 05-05-2015, 08:58 AM

Return line.

**MikeB** · 05-05-2015, 10:53 AM

Quote:

Originally Posted by hatzie

Return line.

Interesting. How does it work vs. a pump with no return line?

There are no lines other than a 3/8" fuel line that terminate on the passenger side of the engine, The second hard line from the fuel tank (5/16") terminates at the evap canister on the driver's side.

The truck originally had a 250 six, so I guess I need to dig through the 82 shop manual to see how 250 and 350 fuel lines and evap canister connections differ.

**MikeB** · 05-05-2015, 11:50 AM

OK, I see where the fuel return line is used to reduce chances of vapor lock. Not all 82 engines used it.

But all engines did use a line from the fuel tank to the evap canister. Guess they may have been a third line on some trucks.

enaberif · 05-05-2015, 12:44 PM

Quote:

Originally Posted by hatzie

Return line.

There is no return on the dual nipple.

One nipple is the feed line from the tank and the other line runs to the carb. The fuel can flow backwards but its not a return line.

lindstromjd · 05-05-2015, 07:03 PM

Quote:

Originally Posted by enaberif

There is no return on the dual nipple.

One nipple is the feed line from the tank and the other line runs to the carb. The fuel can flow backwards but its not a return line.

Then how do you explain the outlet port right next to the other two nipples? It's got 3 ports... one of them has to be something other than the tank feed and carb feed.

enaberif · 05-05-2015, 08:28 PM

Quote:

Originally Posted by lindstromjd

Then how do you explain the outlet port right next to the other two nipples? It's got 3 ports... one of them has to be something other than the tank feed and carb feed.

The question was a bit misleading.. I apologize.. here is a diagram to help explain.

Titomars · 05-05-2015, 08:55 PM

Quote:

Originally Posted by enaberif

There is no return on the dual nipple.

One nipple is the feed line from the tank and the other line runs to the carb. The fuel can flow backwards but its not a return line.

It is a 3 port pump. The outlet to the carb is for a hard line (threaded)
3/8th nipple is the inlet
5/16th is the return port to the tank.
not all trucks had the 3rd port. six's did not come with them. all 454's did. the SBCs it was based on certain engine codes

motornut · 05-05-2015, 10:39 PM

In my Jimmys the 78K -305 is two line no charcoal can.
Both 79s 305C and 350K have the third line and a can.

**MikeB** · 10-04-2015, 10:45 AM

FYI, I traded in my pump for one without the return line. The new one is for use in various vehicles from 69 to 79, and has a 3/8" hose nipple and 3/8" inverted flare outlet fitting (5/8"-18 threads). So I'm good to go and don't have to worry about a rubber cap cracking.

Mine's the O'Reilly Auto parts "Precision" brand, but appears to be identical to Carter #M4685 that Summit Racing sells for only $13. Think I might buy a spare at that price. I've spent almost as much on a margarita!

piecesparts · 10-05-2015, 04:07 PM

Quote:

Originally Posted by enaberif

There is no return on the dual nipple.

One nipple is the feed line from the tank and the other line runs to the carb. The fuel can flow backwards but its not a return line.

Nope, that ain't it. The picture has two nipples and also a threaded fitting. The larger nipple is the feed from the tank, the smaller is the return to the tank and the threaded fitting goes to the carburetor. The smaller nipple is ported, so that a small percentage of fuel is returned to keep the fuel pump cooled, when the carb is not demanding a large amount of fuel.

motornut · 10-06-2015, 09:53 AM

This?
the two line was for the 78
3 is 79,tank is too

05-05-2015, 08:33 AM	#1
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,597	fuel pump with two nipples An AC-Delco #41216 fuel pump for a 1982 C10 with 350 engine has two hose nipples. What is the smaller one for? __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

05-05-2015, 08:58 AM	#2
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: fuel pump with two nipples Return line. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

05-05-2015, 10:39 PM	#9
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: fuel pump with two nipples In my Jimmys the 78K -305 is two line no charcoal can. Both 79s 305C and 350K have the third line and a can. __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

10-04-2015, 10:45 AM	#10
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,597	Re: fuel pump with two nipples FYI, I traded in my pump for one without the return line. The new one is for use in various vehicles from 69 to 79, and has a 3/8" hose nipple and 3/8" inverted flare outlet fitting (5/8"-18 threads). So I'm good to go and don't have to worry about a rubber cap cracking. Mine's the O'Reilly Auto parts "Precision" brand, but appears to be identical to Carter #M4685 that Summit Racing sells for only $13. Think I might buy a spare at that price. I've spent almost as much on a margarita! __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!

10-06-2015, 09:53 AM	#12
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: fuel pump with two nipples This? the two line was for the 78 3 is 79,tank is too Attached Images __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

05-05-2015, 11:50 AM	#4
MikeB Senior Member Join Date: Jul 2000 Location: North Texas Posts: 3,597	Re: fuel pump with two nipples OK, I see where the fuel return line is used to reduce chances of vapor lock. Not all 82 engines used it. But all engines did use a line from the fuel tank to the evap canister. Guess they may have been a third line on some trucks. __________________ Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then!



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