Fuel pump + line fittings

[RCSB_jonny]

I tried searching but couldn't quite find an answer, so here we go.

I'm replacing my gas tank, fuel pump, and rear fuel lines up to the filter on my '93 RCSB 5.7L. I ordered all the parts and have them here at my house, but the truck is at my parents' farm. Needed something to tinker with while quarantining (just came back to Canada).

I ordered a stainless hard line set with braided hoses from Lines to Go. This kit: 1993 Chevy truck fuel lines for K Series 4WD Gas Reg Cab 6.5ft box5.7L. Stainless Steel

And I ordered this AC Delco sending unit from Rock Auto: ACDELCO MU2429 Gold / Professional; Includes Sender

The return line (5/16) fits fine, but the supply line does not want to screw onto the sender fitting. The tread only barely catches then doesn't want to screw on more. It feels like it's hitting metal first, vs the other line where I can feel it hit the rubber O-ring first.

Is it possible that the flare isn't proper on the sending unit? I don't want to try reefing down it yet for fear of stripping threads or something.

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[mtl111]

I would verify the threads on the line and sending unit are the same with a thread pitch guage. I would also compare the new parts to the old and see if the flare is the same. You could use a caliper and measure. I wouldn't assume they're correct and attempt to tighten it down and cross thread.

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[Schurkey]

Contact the folks you bought it from. Have them verify that the parts are intended to fit together.

I'm surprised to see a black O-ring on the fuel system.

 

[Queso Del Rio]

The Sending Unit website you linked to says one is a 14 and the other is a 16 thread pitch. Pitch gauges are pretty inexpensive and come in real handy. Just curious, does the brass union that came with the lines fit on the flare nut? If so, it'll be good to bring up to the customer service folks too.

 

[RCSB_jonny]

The Sending Unit website you linked to says one is a 14 and the other is a 16 thread pitch. Pitch gauges are pretty inexpensive and come in real handy. Just curious, does the brass union that came with the lines fit on the flare nut? If so, it'll be good to bring up to the customer service folks too.

No brass union. I see that it's in the one picture on the lines website, maybe that's the missing link.

I'll see about measuring the pitch, and give the lines people a call.

 

[JeremyNH]

I just put a marine intake in two weeks ago so have been through the fuel line adapters. You need to use an O-ring to 6AN adapter between the fuel line fitting and your 6AN line. The part I used for the 16mm line was this:

https://www.summitracing.com/parts/FRA-491971-BL

It could be that your kit has an adapter as the sole fitting but if it isn't threading right I'd be suspicious that it may be expecting a standard AN flare instead of an O ring seat. I'd check the 14mm line as well. Just because it threads doesn't mean that it will seal if the seat isn't right.

 

[RCSB_jonny]

I just put a marine intake in two weeks ago so have been through the fuel line adapters. You need to use an O-ring to 6AN adapter between the fuel line fitting and your 6AN line. The part I used for the 16mm line was this:

https://www.summitracing.com/parts/FRA-491971-BL

It could be that your kit has an adapter as the sole fitting but if it isn't threading right I'd be suspicious that it may be expecting a standard AN flare instead of an O ring seat. I'd check the 14mm line as well. Just because it threads doesn't mean that it will seal if the seat isn't right.

Thanks for the link!