Bill Parsons Posted March 28, 2019 Report Share Posted March 28, 2019 After recently rebuilding my fuel pump, I noticed some perceived oddities with the fuel supply as I was reinstalling it. I have never done any work on a fuel supply line before so this is all new territory for me. This may be a stupid question, but is the fuel supply line supposed to be the same size from the gas tank to the carb? The gas tank line is a steel 5/16" line that ends near the frame. Then a 5/16" rubber hose is clamped onto the end of that. What I don't understand is why both the fuel pump inlet and outlet lines are 1/8" as well as the carb inlet. Is that the way it usually is? The rubber hose goes onto a reducer barb that screws into the fuel pump, and two more reducers on the pump outlet to the steel line and the inlet to the carb. Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted March 28, 2019 Report Share Posted March 28, 2019 tubing and pipe sizes are not a 'hand in hand' size.... Quote Link to comment Share on other sites More sharing options...
Bill Parsons Posted March 28, 2019 Author Report Share Posted March 28, 2019 1 hour ago, Plymouthy Adams said: tubing and pipe sizes are not a 'hand in hand' size.... So this is normal? 5/16" steel and 5/16" tube connecting to a 1/8" connection on the carb and pump? I also failed to add that the steel line between the fuel pump and the carb is also 5/16" with reducers at both ends. Quote Link to comment Share on other sites More sharing options...
Los_Control Posted March 28, 2019 Report Share Posted March 28, 2019 yup, seems like exactly what I have. The purist will tell you to use 5/16" as original .... but if it was reduced to smaller why bother? Thinking I will stay 5/16" just because I can reuse the original fittings, everything will fit together. IMHO, I see no reason to stay 5/16" just because the factory did .... then jumped back and forth in sizes. And no, 5/16" is not a common size to buy at your local parts store. Quote Link to comment Share on other sites More sharing options...
Fernando Mendes Posted March 29, 2019 Report Share Posted March 29, 2019 Excuse me but I am not believing.1/8" is very thin.Is not it 1/4"? Quote Link to comment Share on other sites More sharing options...
NiftyFifty Posted March 29, 2019 Report Share Posted March 29, 2019 5/16 steel line is the OD, 5/16 rubber line is ID, and yes I can’t imagine it’s 1/8th, possibly a 1/4 ID but 1/8th would never run the truck properly, and 1/4” would be suspect for proper flow as well. Should be 5/16 steel from tank to just before carb, then a short chunk of 5/16 ID rubber. Quote Link to comment Share on other sites More sharing options...
Bill Parsons Posted March 29, 2019 Author Report Share Posted March 29, 2019 This is my fuel pump. The engine is not original to the truck and comes from a desoto. If you look at the specs, you will see that it is 1/8". Quote Link to comment Share on other sites More sharing options...
Plymouthy Adams Posted March 29, 2019 Report Share Posted March 29, 2019 (edited) you are aware that the 1/8-27 is national pipe taper and is that these barbs come in a variety of hose size for connection to meet you flow desire......here is just one....the pictured barb is for a 3/8 rubber hose they are also available for AN connections or inverted flare etc..... Edited March 29, 2019 by Plymouthy Adams 1 Quote Link to comment Share on other sites More sharing options...
kencombs Posted March 29, 2019 Report Share Posted March 29, 2019 As PA stated, the 1/8 is not actual size. It is 1/8 pipe, which is lot bigger that 1/8" at .405in OD. 2 Quote Link to comment Share on other sites More sharing options...
Bill Parsons Posted March 29, 2019 Author Report Share Posted March 29, 2019 Thank you guys for the info! I did not know about how NPT works. I think googling this will help me going forward. Quote Link to comment Share on other sites More sharing options...
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