How to connect fuel pump to carburetor on 48 DeSoto?

[MarcDeSoto]

I'm missing the line that connects the fuel pump to my carburetor.  I bought a 12" section of 5/16 fuel line today.  My plan is to screw one end into the pump, then cut the line in half with a hack saw.  Then, screw the other end into the carburetor.  Then, put a fuel filter and hoses to connect the severed fuel lines.  Does that sound correct, or am I doing something wrong?

[Dodgeb4ya]

Always use a razor blade, box cutter, sharp knife or hose cutter to cut fuel hose..

Makes a straight debris free professional cut.?

Edited June 16, 2022 by Dodgeb4ya
Spelling correction

[MarcDeSoto]

Yes, I'll cut the hose with a razor blade, but otherwise is my metal fuel line setup like the original?  

[Merle Coggins]

A tubing cutter will give you a cleaner, straighter, cut without debris. 

[Doug&Deb]

The original wouldn’t have a filter but adding one is good insurance. Keep the line as far from the manifold as possible. Glass bowl filters that screw into the carb are available also.

[vintage6t]

Not sure of the original configuration, but I'd put the fuel filter before the fuel pump inlet and just a straight line from fuel pump outlet to carb. That will keep debris out of the fuel pump.

[Young Ed]

What you described is how I have my Plymouth setup. I also have the line as far over to the inner fender and away from the engine heat as possible 

[MarcDeSoto]

I just found out that the 5/16 line that screws into the carburetor does not screw in the fuel pump.  What's going on there?  Do you have to use reduction fittings to get it to fit?  I just looked up the fuel pump to carburetor tube in the Parts Manual.  The tube is 26" long with 5/16 fittings.  My fuel pump can not take a 5/16 fitting.  

Edited June 17, 2022 by MarcDeSoto

[MarcDeSoto]

I looked at OReillys and found that the closest line they have to 26" long is this 30" long PVF brake line.  Will that work as a fuel line?  

 

https://www.oreillyauto.com/detail/c/american-grease-stick/american-grease-stick-steel-polyvinyl-fluoride-pvf-30-inch-brake-line/ags0/pa530/v/a/21216/automotive-car-1948-desoto-s-11?q=5%2F16+brake+line&pos=2

[Doug&Deb]

Your best bet is to make your own line. Nickel copper line is easy to work with and lasts forever. My pump has 1/8-27 npt fittings so I have an adapter on the pump. 

[RobertKB]

19 hours ago, MarcDeSoto said:

I just found out that the 5/16 line that screws into the carburetor does not screw in the fuel pump.  What's going on there?  Do you have to use reduction fittings to get it to fit?  I just looked up the fuel pump to carburetor tube in the Parts Manual.  The tube is 26" long with 5/16 fittings.  My fuel pump can not take a 5/16 fitting.  

 

You should be able to see what’s needed. 

 

 

Edited June 18, 2022 by RobertKB

[Sam Buchanan]

19 hours ago, MarcDeSoto said:

I just found out that the 5/16 line that screws into the carburetor does not screw in the fuel pump.  What's going on there?  Do you have to use reduction fittings to get it to fit?  I just looked up the fuel pump to carburetor tube in the Parts Manual.  The tube is 26" long with 5/16 fittings.  My fuel pump can not take a 5/16 fitting.  

The fuel pump is probably NPT threads. You need an elbow with male NPT threads and female threads and inverse flair for the brake line.

 

Edited June 17, 2022 by Sam Buchanan

[MarcDeSoto]

Does anyone know where to get the right fittings for the fuel pump to carburetor connections.  I need a 3/16 male to 5/16 female connection to go from the fuel pump to the fuel line.  And preferably, it should be an elbow per Robert's pic above.  No one seems to sell this size.  

Edited June 19, 2022 by MarcDeSoto

[Sam Buchanan]

1 hour ago, MarcDeSoto said:

Does anyone know where to get the right fittings for the fuel pump to carburetor connections.  I need a 3/16 male to 5/16 female connection to go from the fuel pump to the fuel line.  And preferably, it should be an elbow per Robert's pic above.  No one seems to sell this size.  

 

The threads on the fuel pumps are most likely 1/8" NPT. This is not the OD of the threads so don't be confused by this.  If not 1/8", they will be 1/4". You need a good old-school auto parts house that has bins of brass fittings they can pick through....the computer elves at the chain stores won't have a clue what you want.

 

This what you want:

 

https://www.amazon.com/Inline-Tube-Degree-Thread-Inverted/dp/B06ZYHZBDP/ref=sr_1_2?crid=QPDAC46G7I8B&keywords=1%2F8"+npt+to+brake+line+elbow&qid=1655603468&sprefix=1%2F8+npt+to+brake+line+elbow%2Caps%2C92&sr=8-2

 

[9 foot box]

   The fuel line from the pump to the carburetor should be 5/16 OD. That would make the ID close to 1/4”. A 3402-05-02 is a 90 degree fitting that adapts a 1/8” npt fuel pump thread to a 5/16” OD inverted flare tubing. I wouldn’t use smaller tubing to supply fuel to the carburetor. It keeps it simple to have the same 1/2”-20 thread as the needle valve fitting at the carburetor. Rick D. 

[MarcDeSoto]

My fuel line is 5/16.  The fitting that Sam shows is I think for 3/16 line.  So who's right here?  Would this be the right fitting for me?  

 

https://www.amazon.com/Weatherhead-402X5-Inverted-Fitting-Degree/dp/B00BKFIDU8/ref=sr_1_15?crid=X7NNN4ROCS3M&keywords=90+Degree+Brass+Elbow+with+Male+1%2F4"+Npt+Pipe+Thread+and+Female+Inverted+Flare+for+5%2F16"+Brake+Line&qid=1655621431&sprefix=90+degree+brass+elbow+with+male+1%2F4+npt+pipe+thread+and+female+inverted+flare+for+5%2F16+brake+line%2Caps%2C123&sr=8-15

Edited June 19, 2022 by MarcDeSoto

[joecoozie]

I would go to NAPA with the fuel pump and the fuel line(s) and let them match up what you need.

[andyd]

As a general rule the brass fittings that screw into the carburetor and fuel pump "should" be 1/8th NPT....this IS NOT the same as a 1/8th diameter piece of pipe but a SPECIFIC pipe thread that will screw into the carburetor and fuel pump and have an internal thread that will allow the steel fitting on the pipe with the flared end to screw into the brass union and allow the flared pipe to seal inside the brass fitting......see the picture on Sam Buchanans post..........also in the pic from RobertKB's post....these brass fittings are available as 180,90 & 45 degree angled pieces that will allow the fuel pipe to be attached at whatever angle is needed........whilst the brass fittings generally should not need any teflon tape to help seal them as they screw into the carby/fuel pump the steel fitting into the brass may need some teflon tape........also the brass fittings can be obtained with both a straight male thread and a TAPERED male thread, both with the correct internal female thread, the straight thread may screw in easier BUT may bottom out whereas the tapered thread fitting will usually seal before bottoming out due to the tapered thread but may not be at the correct angle when tightened to suit the angle of the fuel line..........so ain't cars fun........lol............andyd 

[kencombs]

7 hours ago, MarcDeSoto said:

My fuel line is 5/16.  The fitting that Sam shows is I think for 3/16 line.  So who's right here?  Would this be the right fitting for me?  

 

https://www.amazon.com/Weatherhead-402X5-Inverted-Fitting-Degree/dp/B00BKFIDU8/ref=sr_1_15?crid=X7NNN4ROCS3M&keywords=90+Degree+Brass+Elbow+with+Male+1%2F4"+Npt+Pipe+Thread+and+Female+Inverted+Flare+for+5%2F16"+Brake+Line&qid=1655621431&sprefix=90+degree+brass+elbow+with+male+1%2F4+npt+pipe+thread+and+female+inverted+flare+for+5%2F16+brake+line%2Caps%2C123&sr=8-15

This gets real confusing as the female  thread size in the fitting would be the same for several tube sizes.  3/16, 1/4 and 5/16" tube nuts can all be had for that 3/8 thread.

 

I'm looking at brake tubing kits on the Bay, and most of them come with tube nuts of that size for all the different tubes normally used.  But all the same thread.

 

 

[MarcDeSoto]

I called my local NAPA.  They don't have it in stock, but say they can have it by tomorrow.  I asked for a 1/8 npt male thread with a 90 deg. angle going to a female 5/16 thread. I hope that's right.  I will take my fuel line and fuel pump to verify when I go to the store.  

[kencombs]

56 minutes ago, MarcDeSoto said:

I called my local NAPA.  They don't have it in stock, but say they can have it by tomorrow.  I asked for a 1/8 npt male thread with a 90 deg. angle going to a female 5/16 thread. I hope that's right.  I will take my fuel line and fuel pump to verify when I go to the store.  

Depends on how the store interpreted the 5/16 thread spec.  It is a 5/16 tube but the thread size is 3/8.   x 20 I think.

[MarcDeSoto]

Wish I could have gotten that info a few days ago.  But if it's wrong I'll just re-order till it's right.  Just for the record, this is how the DeSoto s-11 Parts Book describes the fitting.  

 

For engine numbers not between the numbers below -  My engine number is 213562.  Connector, inverted flared tube, 5/16" tube, 1/8" taper pipe thread,  1/2" - 20 thread, tubing end.  I guess that means my engine did not come with the elbow version?  But I don't see why I can't use an elbow.  

That 1/2" size is confusing me!  

 

For engine numbers 124436 to 129256  -  Elbow, inverted flared tube, 5/16 tube diameter, 1/8" taper pipe thread, 3/8"-20 thread tubing end.  

Edited June 20, 2022 by MarcDeSoto

[andyd]

Marc..........the tube used is 5/16th diameter, the brass adaptor uses a male 1/8th pipe thread to screw into a 1/8th pipe threaded female "hole" in either the fuel pump or carby.........the 1/2" bit is the AF or Across Flats size of the steel tube nut, on the steel tube that screws into the brass fitting or adaptor.........the "20" is the thread count on this steel tube nut and also the thread count in the female part of the brass tube nut............as for whether you or your car use a straight, 90 or 45 degree brass adaptor that is immaterial...............you and your car use whatever brass fitting that it needs or you decide to use depending on the angle of the steel fuel line with its attached tube nut......lol......you are overthinking all this.......lol........Andy Douglas     

[MarcDeSoto]

I have this old NOS in the box Zenith fuel filter, but I don't know how to connect it.  I went to NAPA to see if they had the right fitting for it, but he said no.  It is 1/8 thread on the carburetor side and 5/16 fuel line size on the inlet side.  I would need a nipple that is 5/16 male inverted flare on one side and 1/8 npt on the other.  

 

 

Edited June 20, 2022 by MarcDeSoto

[Sam Buchanan]

You just need a 1/8" NPT male nipple. Use it to connect the filter to the upstream (fuel tank) side of the pump, and put the fitting you have for the upstream side of the pump on the filter so you can connect the fuel line coming from the tank. The pump and filter become one unit. Done. Or am I missing something here.....

 

 

Or this if you want a little space between filter and pump....whatever works best for your installation. Don't overthink this....we're talkin' plumbing 101.....  ?

 

 

But I like the shorter nipple better so the mass of the filter isn't hanging on the end of a long nipple.

Edited June 20, 2022 by Sam Buchanan