Another fuel leak!

[Daveo91Burb]

Making progress on 383 build and install - got ready to at least crank her over in the truck on Saturday. (I've already run the engine outside the truck with a carb and it's roller cam so no break in worries). Got her to crank over a couple times, but puddle of fuel on the ground afterward and I could actually hear it leaking while cranking. Right below the lines. It's not coming from the connections at the frame rail to the flex lines. It's also not coming from the connections at the TB - manifold was dry. I think the supply line has been kinked or damaged. I found what could be a tiny crack in the hard section. It also could be damaged in the flex section.

But here's the rub....I'm not seeing where I can buy just that one line with braided flex up to the engine and then pre-bent hard line the rest of the way to the TB. Rock Auto has a kit that supposedly has all the lines included for over $200, but really don't want to go that way. Nothing on Amazon or e-bay either? Am I looking in the wrong places or using wrong search terms? Maybe I should go braided the entire way?

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[yevgenievich]

Repair that section only. There are adapter fitting for hard line and for the tbi unit. And just put -8 an flex line in-between. Or from a part out. I would offer a line from my parts suburban but I am using it for now.

 

[chengny]

GM part numbers are 15548991 (feed) and 15548993 (return). But it is really hard to find an OEM set.

Call inline tube - they may make them but they don't show your exact application (at least I don't think they do). It is very hard to tell. They make nice tubes, but their website is the worst I have seen. Slow and extremely vague descriptions. You'll understand if you go there.

https://www.inlinetube.com/_p/prd14/2842630701/product/1981-87-v8-3-8"-f.i-main-fuel-lines-ctf8151

 

[Daveo91Burb]

Thanks guys. As I was typing the original post last night I started wondering if saved the lines from my '90 parts rig. Just now was the first chance I got to go out and look and sure enough I did, but they're different. On the '90 the braided part was way up by the TB whereas on the '91 in the pic it's pre-bent up by the TB and braided on the lower section. Much less braided section on the '90, too. Would they have changed designs between '90 and '91? Although it's also possible that either one of the POs changed something out.

I may end up doing the repair or just going to Pick-n-pull this weekend.

Can I test the lines and find the leak by hooking them up to the TB out of the truck and then turning the key to prime the pump?

 

[yevgenievich]

Testing as described should be fine. I would actually use the fuel pump test wire that comes off from the relay so it would run longer

 

[Daveo91Burb]

Excellent, will do. I always wondered what that wire was for - should have known it was to test. Hook it up to 12v or ground it?

 

[4WDKC]

I had to bend and tweak my lines to work with the new intake and adapter. IMHO you would be better off taking the opportunity to splice in a
Schrader valve while repairing that line than getting another OEM line with out the valve

 

[yevgenievich]

12v power

Excellent, will do. I always wondered what that wire was for - should have known it was to test. Hook it up to 12v or ground it?

 

[Daveo91Burb]

Did some testing tonight, method described above. Guess it's not the lines after all. I think it was actually coming out the supply connection at the TB and running down the line, dripping off the low spot. Redid all the connections at the TB (I have a pressure gauge there so there are several) with gasoline-rated pipe dope paste. Instructions on the dope said to wait overnight for gasoline so tomorrow night I'll test and see where I'm at. Thanks for the input.

 

[yevgenievich]

The o ring should be doing all the sealing. Threads are not used for sealing on these connections.

Did some testing tonight, method described above. Guess it's not the lines after all. I think it was actually coming out the supply connection at the TB and running down the line, dripping off the low spot. Redid all the connections at the TB (I have a pressure gauge there so there are several) with gasoline-rated pipe dope paste. Instructions on the dope said to wait overnight for gasoline so tomorrow night I'll test and see where I'm at. Thanks for the input.

 

[rpcraft]

I'm doing an LS swap, so a bit of a different issue, but I replaced all the steel lines with 3/8 and 5/16 Dorman OEM style Nylon fuel lines and am just going to use some insulated clips at the mounting points. I used a fitting on the fuel tank that is barbed on one side with FI clips and compression to the sending unit pipes. I am workign on a K5 so I need a union but on a truck you could get away with one spool each and then the connectors would probably only amount to 50 or so bucks. I have some DEI heat sheild I am going to use on any place it is near heat to protect it. If you want I can post up a graphic with some part #'s. Just have to find it again.

Food for thought

 

[rpcraft]

Dorman parts -

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Photo of FI clips, I just used some bull nose wire cutters to crimp them down.

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Picture of crimp and compression fittings coming off the tanks:

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[Daveo91Burb]

The o ring should be doing all the sealing. Threads are not used for sealing on these connections.

Understood but I also have threaded connections for the pressure gauge and a small pipe plug - I think it was at least seeping from those.

But speaking of the o-rings in those connections - can you buy those by themselves without a TBI rebuild kit? Or can I use generic viton o-rings? I couldn’t find those in my box of rebuild parts so I had to reuse existing - that may also be my problem.


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[yevgenievich]

Parts stores usually carry an universal kit with different sizes. I just had to buy some for my other suburban. If threads are npt style then they do seal on threads, if fitting has oring or angled mating surfaces then the threads play no part in sealing.

Understood but I also have threaded connections for the pressure gauge and a small pipe plug - I think it was at least seeping from those.

But speaking of the o-rings in those connections - can you buy those by themselves without a TBI rebuild kit? Or can I use generic viton o-rings? I couldn’t find those in my box of rebuild parts so I had to reuse existing - that may also be my problem.


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[Daveo91Burb]

I'm doing an LS swap, so a bit of a different issue, but I replaced all the steel lines with 3/8 and 5/16 Dorman OEM style Nylon fuel lines and am just going to use some insulated clips at the mounting points. I used a fitting on the fuel tank that is barbed on one side with FI clips and compression to the sending unit pipes. I am workign on a K5 so I need a union but on a truck you could get away with one spool each and then the connectors would probably only amount to 50 or so bucks. I have some DEI heat sheild I am going to use on any place it is near heat to protect it. If you want I can post up a graphic with some part #'s. Just have to find it again.

Food for thought

Looks like a good way to go for your LS swap. If I had to go away from stock lines I'd definitely consider this. But although my stock lines are a very tight fit they do fit and I can get them hooked up (and now I know they don't leak).