Help sorting out mech. fuel pump? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cam.man67 · 01-29-2014, 06:55 PM

Decided to replace the fuel pump on Lester, we'll see if it gets him running again. Got fuel up to there, so it should. Here's the confusing part:

The pump I pulled off and the new one look identical...except that teh old one had a line close tot he inlet. Oddly it ran to the fuel filter. It doesn't look like the primary fuel inlet, so my question is what is the purpose that inlet/oulet/bypass/whatever? Do I need it? Is it a deal-break that the new pump doesn't have it? Does it have something to do with the fact that the orignial engine was a Olds diesel? The old pump part number is Carter 0-1955.

cam.man67 · 01-30-2014, 06:48 AM

Ok, so I;ve been reading...looks like the mechanical fuel pump I took off had a return line and for whatever reason, that was the line the PO put the filter on. Now the question is...do I need that return line? Or can I cap it off and not worry about it?

motornut · 01-31-2014, 10:57 AM

the main is 3/8
vent is 5/16
the return is 1/4 and it helps with vapour lock
better to use the right one
but i've seen the two line used instead of three

dwntwn · 02-05-2014, 12:59 PM

X2 what Motornut said.
I've capped the return line and had no issues, other times had flooding and hot-start issues. Not worth the headache, just get the right one, you'll probably be happier in the long run

01-29-2014, 06:55 PM	#1
cam.man67 Registered User Join Date: Jun 2010 Location: Jefferson, MD Posts: 2,397	Help sorting out mech. fuel pump? Decided to replace the fuel pump on Lester, we'll see if it gets him running again. Got fuel up to there, so it should. Here's the confusing part: The pump I pulled off and the new one look identical...except that teh old one had a line close tot he inlet. Oddly it ran to the fuel filter. It doesn't look like the primary fuel inlet, so my question is what is the purpose that inlet/oulet/bypass/whatever? Do I need it? Is it a deal-break that the new pump doesn't have it? Does it have something to do with the fact that the orignial engine was a Olds diesel? The old pump part number is Carter 0-1955. __________________ '68 Dodge Dart 270, 225, 904, 2.76--"Lucy" 1996 Gmc 1500 Z71, 350, 4l60e, 3.73s 1995 Jeep Wrangler Rio Grande 2.5, AX5, 4.10s 1989 Toyota Pickup 22re, auto, 3.73 Last edited by cam.man67; 01-29-2014 at 07:01 PM.

01-30-2014, 06:48 AM	#2
cam.man67 Registered User Join Date: Jun 2010 Location: Jefferson, MD Posts: 2,397	Re: Help sorting out mech. fuel pump? Ok, so I;ve been reading...looks like the mechanical fuel pump I took off had a return line and for whatever reason, that was the line the PO put the filter on. Now the question is...do I need that return line? Or can I cap it off and not worry about it? __________________ '68 Dodge Dart 270, 225, 904, 2.76--"Lucy" 1996 Gmc 1500 Z71, 350, 4l60e, 3.73s 1995 Jeep Wrangler Rio Grande 2.5, AX5, 4.10s 1989 Toyota Pickup 22re, auto, 3.73

01-31-2014, 10:57 AM	#3
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: Help sorting out mech. fuel pump? the main is 3/8 vent is 5/16 the return is 1/4 and it helps with vapour lock better to use the right one but i've seen the two line used instead of three __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

02-05-2014, 12:59 PM	#4
dwntwn Registered User Join Date: Oct 2012 Location: Tucson, AZ Posts: 101	Re: Help sorting out mech. fuel pump? X2 what Motornut said. I've capped the return line and had no issues, other times had flooding and hot-start issues. Not worth the headache, just get the right one, you'll probably be happier in the long run __________________ _____________________________________________ 1966 c10, short fleet, 402ci 700r4 1988 r20 Suburban 454ci tbi, th400 (12v Cummins soon) 1980 shovelhead, hardtail, open primary 1998 FXDWG



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.