Revamping the Fuel System

[TheGoose]

Hi All.

I have started working on our 1983 6.2L diesel truck as noted in this thread here:
https://www.thedieselpageforums.com/tdpforum/showthread.php?t=36577

I have a question about the fuel system. Bear in mind that the truck has been stored in a barn for 20 years and has not been ran any during that time.

We plan to drop the fuel tank and most likely replace it. We will also replace the fuel lines from the fuel tank to the fuel pump that is located on the block. Does anybody know if these fuel lines are rubber or metal? I have not yet got that far but we have begun ordering the parts and I would think that if they are metal we could flush them really well. We will replace any rubber hoses/parts as well as the filter.
We are also going to replace the fuel pump on the block and the fuel lines from there to the injection pump (via the filter). I will probably need to flush the fuel that is in the injector pump out, maybe through the injector lines (disconnected at the block) but I'm not sure how.

Any ideas, advice, or suggestions welcome. I've ordered the book from this site, I hope it comes in soon.

[Yukon6.2]

The lines are metal and rubber
Myself i would drop the tank,either clean or replace and pressure test the fuel system,fix any leaks,then run it.
If the old lines don't leak i wouldn't change them,replacement rubber lines may be made of inferior rubber and only last a few years.
I see that a lot new trailers with rotten valve stems made in China,yet old tires from the 80's the stems are still good.

[TheGoose]

I’m going to replace the fuel tank, the new one is inexpensive and the old one was known to have a leak. I can’t see reusing the fuel lines that are nearing 40 years old but I’ll try to make sure the new ones are quality material.

[a5150nut]

If you can find a parts store that deal in OTR truck parts you might get better quality fuel line. They aren't stocking according to price point like your "on the corner parts stores. "

[TheGoose]

So any good ideas to prime the system after installation of the new fuel tank/ fuel lines/ fuel pump? My idea was to put a little pressure on the tank with the lines open ended at the 1st fuel pump, then connect to fuel pump once diesel purges out. Then purge at the filter, then purge at the injector pump.

[DmaxMaverick]

Sounds like a plan, if you're trying to purge contaminants. Otherwise, I'd just open the last fitting you can reach, and purge it entirely at once. Be patient and don't try to push it too fast.

[TheGoose]

So the current plan is to keep all the metal lines but replace all the little rubber transition pieces. Does anybody know what sizes the rubber pieces are? Looks like 1/4 or close to it? Haven’t yet removed any.

[TheGoose]

OK stupid question. Replacing the tank, one of the straps fits fine the other is really tight. We're putting a little rubber backing around the strap and that seems to make it not fit. Is one strap shorter than the other and maybe we need to switch the straps? I know our rubber piece is a little thicker than necessary but it shouldn't be enough to keep it from making the connection on the strap.

[DmaxMaverick]

The tank straps are a tight fit with the OEM insulators, which are quite thin. If you're using a thick rubber insulator, it will be very tight. It's also possible that variations in the aftermarket tank shape may complicate it. If it doesn't distort the tank, I'd just tighten it, or tighten it just shy of that. Tighter is better than looser. Loose straps will wear a hole in the tank over a short period.

[TheGoose]

Having a rough time finding the fuel filler hose that goes from the fuel door to the fuel tank for a stepside. Can find the fleetside all day long but the step side makes some funky bends to get there. I'm not sure if we can just buy a hose and make the necessary bends without kinking it. Any sources for things like this? I've check the GM dealer, LMC truck, etc. Nothing that is exclusively for a 1983 C10 diesel stepside.

[DmaxMaverick]

It's a lot cheaper and easier to just have a muffler shop bend a pipe for you, and use hose to connect the ends. It's a snap if you have the original to use as a template. Stainless steel is more expensive, but well worth it (and still less expensive than an OEM replacement, if you can find one).

Another option is finding one in a wrecking yard. Good luck with that!

[TheGoose]

Here’s the stock one and one that might fit from LMC.

[TheGoose]

Judging by how few step side diesels there are from that era I'm skipping the junkyard.

It does look like there are some hoses out there for stepsides that are not 1983 but look very similar to what I need. Do you know if there is any harm in using a "gasoline" rated hose for diesel?

[DmaxMaverick]

There's nothing wrong with using gasser hoses for Diesel, but I'm pretty sure they are a different size, shape. Even tanks of the same size have different size hoses, as well as having different angles and boss locations. There's a reason why you aren't finding the correct piece. If the bends/lengths were close, the aftermarket would have figured it out (universal parts). Having a kink in the filler hose, even a little, will come back to haunt you. Been there. Done that. At least one of them was for a 1983, and it was a gasser fleetside (20+ years ago). Got new tanks that were an exact match by part number, but the bosses were smaller and in the wrong location. Every other tank in stock was the same. This truck was a mid-west import to CA, but that's the only difference we could find. I suspect it had something to do with the smog region. We ended up making a temporary pipe out of PVC and fittings. Later, we had the muffler shop bend pipe, and used straight sections of the original hose and clamps to connect them. Worked well.

[TheGoose]

There's a reason why you aren't finding the correct piece. If the bends/lengths were close, the aftermarket would have figured it out (universal parts).

I'm not following what this means exactly. You're saying that since there are so few stepsides, and really so few diesel stepsides that there is no aftermarket part available?

I wish we had been more careful removing this. We could not get the hose off so we cut it. I would have never dreamed that this part would not be able to be found without a lot of trouble.

[DmaxMaverick]

Meaning, if the part would fit another application, or be close to it, the aftermarket mfg would list it. This is why many parts "almost" fit, but fit close enough to be useful. This way, they make one part that fits many applications, while the OEMs insist they don't. The stepside Diesels were rare, but not that rare. I've known of many. This in an area where any light duty Diesel vehicle is rare, outside of agriculture. Not many stepside field trucks.

[TheGoose]

I found a radiator hose that fits close enough.