Air intrusion | Replace the olives or replace steel lines

[franklin2]

If you visually inspect the o-ring and its not torn, I would suspect that it's not the problem. Having problems with those o-rings is pretty rare, I have never heard of them giving problems.

Have you checked the sending units for rust? That is a more common problem. You may find some dampness on the lines wherever the leak is.

 

[John_piv]

If you visually inspect the o-ring and its not torn, I would suspect that it's not the problem. Having problems with those o-rings is pretty rare, I have never heard of them giving problems.

Have you checked the sending units for rust? That is a more common problem. You may find some dampness on the lines wherever the leak is.

Sending unit rust would be a good thing to check. On occasion my gas gauges will just ping all the way to full before coming back down, my thought was because of a bad ground. That could be rust, might be worth checking

 

[John_piv]

Update | I attached to clear tube from the quick disconnect fitting on selector valve outlet to the plastic factory fuel line. It has little bubbles in it, which hopefully narrows my search down to selector valve back.

 

[franklin2]

Update | I attached to clear tube from the quick disconnect fitting on selector valve outlet to the plastic factory fuel line. It has little bubbles in it, which hopefully narrows my search down to selector valve back.

Good thinking. A little troubleshooting can save some time and money.

 

[Brian VT]

What type of clear tubing to use for this purpose? And what's the best pace to have a permanent one to keep an eye on what's going through?

 

[Jesus Freak]

What type of clear tubing to use for this purpose? And what's the best pace to have a permanent one to keep an eye on what's going through?

This is what I did in My tow truck. If you look at my thread "Jesus Freaks WMO thread" there's a picture of how I have a glass filter under the hood of my dually. There's no filter it's literally just for watching my fuel for air or anything weird......... because I run all sorts of stuff in my trucks, it's important to watch it.

 

[franklin2]

I would not leave cheap clear hose in the fuel system permanently. It's just for testing purposes. Glass like the other poster used would last ok. But its just another place for a leak. I like steel lines with minimal rubber hose.

 

[John_piv]

What type of clear tubing to use for this purpose? And what's the best pace to have a permanent one to keep an eye on what's going through?

Right now I'm just using 3/8 clear hose from tractor supply. Diesel will eventually eat through it if you ran it permanently, but it's nice for finding problems like this. Permanently you'd likely be better off with the factory plastic-ish lines or steel hardlines.

On that note, does anyone know where to find good lines to use? I think the easiest preliminary parts to replace are the lines from the tanks to the selector. If it keeps going, I'll check the sending units.

 

[chillman88]

For what it's worth, when I go through my truck I'm going to run copper/nickel lines for the fuel lines. Holds up a lot better than steel (corrosion resistant) and bends a LOT easier as long as you're careful.

https://a.co/d/eUtiO3U

A friend of mine used to have the stuff to run new nylon fuel lines and he liked that. I never cared for the stuff much personally, but to each their own.

Stainless would be great but it's crazy expensive.

 

[snicklas]

I may be wrong… but I thought someone on here mentioned you could use semi air line for fuel lines…. I may be thinking of something else…. But this does come to mind…. It may have been Russ @typ4 or he mentioned something else he used it for and I am remembering wrong.

 

[Azidiguy]

I'm not really sure, last time I needed some I bought them locally. Looks like Napa has them?

https://www.napaonline.com/en/p/NOE7306759

I'm sure you know but just in case, feed is 3/8 return is 5/16 and each tank has a pair of quick disconnects too.

Of course you're going to start somewhere and not just do everything but I wanted to cover all the bases.

Honestly I'd just do the feed ones for now. I don't see why you'd need to mess with the return fittings.

It's always POSSIBLE it's internal to the FSV as well, just food for thought if all else fails.

Selectors do wierd stuff mine dosent return right when i switch to the front tank it will seem to go quick but then the previuosly empty tank has some in it. Thos may be why my return caps keep leaking. Something to think on. As far as i know the selectors are unobtainium

 

[chillman88]

As far as i know the selectors are unobtainium

They're not hard to get now, but last I knew they were pretty expensive.

 

[Azidiguy]

They're not hard to get now, but last I knew they were pretty expensive.

Really? Got a source?

 

[chillman88]

Really? Got a source?

I guess they've come down some in price lately.

I see yours is an 86 though so I have no clue if it's different.....

Aftermarket Auto Fuel Pump Replacements | 1A Auto

Engine Misfiring? Shop 1A Auto for quality aftermarket Mechanical Fuel Pumps and In-tank or Inline Electric Fuel Pumps. Order by 4PM for free same day shipping!

www.1aauto.com

 

[John_piv]

UPDATE | After a little more testing, I believe I have narrowed down the problem. I put the quick disconnect directly off the tank into a five gallon can of diesel, and suddenly; no more bubbles! I looked down inside the QD and the seals seemed to be intact, so I'm suspecting the sending unit. I'm going to attempt to replace both SU and see if that solves my problem. If not, I'll work my way forway replacing the lines.

Thanks to y'all for your help so far, even if this isn't the solution!