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73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: xCaliC10x on November 24, 2010, 06:30:33 pm

Title: fuel pump outlet thread size.
Post by: xCaliC10x on November 24, 2010, 06:30:33 pm
I can't find this anywhere. I want to clean up my fuel lines and get rid of the crap job the previous owner left. I ordered the banjo bolt single feed hardline with the russell fuel filter, but when I went to get the nice braided line from the pump to the filter, I can not find what size fitting adapter I need to screw into the pump so I can use the braided line. Someone has to know this one.
Title: Re: fuel pump outlet thread size.
Post by: Irish_Alley on November 24, 2010, 10:36:29 pm
I know its been covered but I can't find it
Title: Re: fuel pump outlet thread size.
Post by: xCaliC10x on November 26, 2010, 12:14:49 pm
I couldn't find it either  ;D Still looking. I will use a piece of 3/8 hose between my setup and the GM fuel pump hardline until I get it figured out.
Title: Re: fuel pump outlet thread size.
Post by: 1982 Daily Driver on November 26, 2010, 04:17:34 pm
I had the same problem and ended up just buying a edellbrock fuel pump.
Title: Re: fuel pump outlet thread size.
Post by: zieg85 on November 26, 2010, 04:26:45 pm
It is smaller than 3/8 pipe thread but the thread pitch is 18 as far as I could match up.
Title: Re: fuel pump outlet thread size.
Post by: xCaliC10x on November 26, 2010, 08:26:39 pm
I had the same problem and ended up just buying a edellbrock fuel pump.

Yeah, thats what I was trying to avoid!
Title: Re: fuel pump outlet thread size.
Post by: 1984k30 on November 26, 2010, 08:54:50 pm
I'm not 100% but it looks like 1/2" 20 thread. It is a straight thread not taper. I had a piece of 5/16 hard line and the fitting that came with it screwed into a fuel pump I had laying around.  checked with thread gauge and was 20 and mic said a little under 1/2"
Title: Re: fuel pump outlet thread size.
Post by: Russ130 on November 27, 2010, 06:55:00 am
The fitting on the pump is meant to mate to a flared tube and for v8's and basically all motors except the small 4 cyclinders it is usually 3/8" tube. The threads do not provide a seal like the pipe thread does, it just holds the flares together for leak free operation so don't bother taping the threads with teflon tape since it won't do any good. Any other way will probably leak though I'm not 100% sure about that. Just make sure the flare is a double flare or a single flare. A double flare looks like it could be used as a golf tee. Most if not all are double flared, I'm willing to bet there is at least one exception. I have found fittings that work perfect for this right near the auxilary coolers at some part stores.
Title: Re: fuel pump outlet thread size.
Post by: xCaliC10x on November 28, 2010, 12:44:39 pm
I was envisioning needing some sort of crush washer if I have the area, since as you said, Teflon tape would just dissolve in minuets. It would seem to be flared like a brake line. I'm sure someone has done this. I may just buy the Edelbrock pump if its gonna be too much work. Just another part I can transfer over to my 388.
Title: Re: fuel pump outlet thread size.
Post by: 1984k30 on November 28, 2010, 02:09:00 pm
What size and thread is the banjo bolt you have?
Title: Re: fuel pump outlet thread size.
Post by: Russ130 on November 30, 2010, 09:01:01 pm
It's not that teflon tape will disintergrate its that this type of fitting does not use the threads as any part of the seal. If the flare fails it will leak between the line and the fitting in the middle not the threads. Its the same type of fitting you have on hard brake lines and older tranny lines but the size is 3/8". You can walk into any parts store and ask for a 3/8" hard line and it will have the propper fitting on it.
Title: Re: fuel pump outlet thread size.
Post by: xCaliC10x on November 30, 2010, 09:20:32 pm
The banjo looks like 1/2? threads I don't know. I will call Russell tomorrow. If they can't get me the right fitting, new pump it is! Thanks guys.
Title: Re: fuel pump outlet thread size.
Post by: rafi pro on February 02, 2011, 08:50:46 pm
the fuel pump is 5/8; but you can lower it down to 3/8 with an adapter at the hardware store. then a fitting  3/8 to 6an from summit will do and continue 6an lone all the way to the filter. it worked for me, hope does for you. keep on trucking
Title: Re: fuel pump outlet thread size.
Post by: 1980c10 on February 02, 2011, 10:58:29 pm
This past weekend I went to the local auto parts store grabbed  a peice of hardline(brakeline) one end fit the oem fuel pump and the other my holley carb. 1st time I tried to bend and re-flair a line. It was easy and took maybe 10 minutes. btw I only had to re-flair one end becuase the line was too long. both ends were the same size. its better than a rubber line or braided lline imo and looks better too