Semi FTB mod makes for improvement

[SlowBoat]

Time constraints forced me into a quick workaround on my FTB upgrade.

A rusty fuel return line at the tank sending unit was causing me grief with a leak and the sending unit replacement showed up some iffy steel lines and flexible lines that needed attention, with no time to wait on ordering them. So I just gathered up my fuel filter parts box of goodies that were going to go under the truck and fabbed a mounting bracket on the PS bracket and relocated them up top. I came directly off the Walbro fuel pump with a 3/8" line up to the Wix fuel filter base using Vibrant Performance -6 90 press-on swivel fittings and over to the injection pump with 3/8" line to a Vibrant Performance -6 90 press on swivel fitting on an Earls -6 to 7/16-20 o-ring base fitting drilled out to 5/16". The injection pump inlet fitting was drilled out to 3/16" holes with a carbide end mill by my machine shop in about 15 minutes. Rusty fuel line bypassed. FFM bypassed for now. (Will be modified when time permits).

My road test was on my "pain in the backside" pull. Before this hill would have me down to 25 MPH and passing the 210 mark on my factory gauge at the top. After cooling upgrades done recently, GM WP, Hayden 2840 fan clutch, Duramax fan, I was able to make it to the top running 185 degrees but still at 25 MPH towing. With my fuel injection fitting mod and fuel lines, I felt like I flew up that pull at 45 MPH! I was absolutely amazed!

I have a few more maintenance mods to perform and then I'm going for an ATT with a KOJO tune.

My younger brother has a 2000 F250 with a massaged 7.3L and he has always ribbed me about my GMC. This last week he actually commented about how well it stayed up with his Ford while I was towing behind him. Now THAT felt good.

 

[Will L.]

Its amazing what can happen when you let the engine get the fuel it wants.
Now when you get the ATT on there with the tune wath what your bro says.

Are you doing injectors also? Grab a set from Leroy, throw them in or get a pop tester and balance them suckers and watch the difference. I bet a set of new injectors, balanced will give you the same feeling of bump you just felt in the fuel supply. Especially if you bring the pop pressure up to 2350 range.

 

[SlowBoat]

Its amazing what can happen when you let the engine get the fuel it wants.
Now when you get the ATT on there with the tune wath what your bro says.

Are you doing injectors also? Grab a set from Leroy, throw them in or get a pop tester and balance them suckers and watch the difference. I bet a set of new injectors, balanced will give you the same feeling of bump you just felt in the fuel supply. Especially if you bring the pop pressure up to 2350 range.

I have a new set of Bosch injectors to go with the planned turbo upgrade. Researching a cold air upgrade to the K47 air cleaner.

 

[SlowBoat]

Well, after a thermostat replacement test drive of 25+ miles, I began to smell diesel fuel getting close to home. I didn't replace that short 1/4" 90 return line on top of the injection pump! It LOOKED good. But, pulling it revealed a small crispy spot on the underside of the 90 that was spraying fuel back at the pump. A quick enough fix, but aggravated at myself for not replacing it while I was there. Note to self, replace all the rubber lines, no matter how good they look!

BTW, the 2 new thermostats, AC Delco PN 12559336, brought the gauge indicated temp up to 190. They replaced the 2 same part numbered stats that weren't coming up to temp. Maybe I will get some fuel mileage improvements.

 

[Will L.]

The line that failed is the one you should repalce with clear tubing for air intrusion and flow diagnostics.

 

[SlowBoat]

I would think that the clear tubing would get brittle from the heat rather quickly. Bad experiences from a LOT of small engines over the years using various types of tubing. It just doesn't seem to hold up well.

I've been considering drilling and tapping my remote fuel filter base for a fuel pressure tap on top. It should handle an electric sending unit fine.

 

[Will L.]

I run clear fuel line for small aircraft currently. It is rated for avgas, so no diesel in the world is going to hurt it. Before that I ran the stuff from home depot for a few years. It will start to tint after a few years, then change it. No biggie- costs all of 5 minutes and $2. If you let it go a decade, you get what you just had, a small leak that took what- 5 minutes to find?

If you add a fuel pressure gauge, inline from ffm to ip is ideal.

Two best things to do for future diagnostics of fuel system.

 

[jrsavoie]

I run clear fuel line for small aircraft currently. It is rated for avgas, so no diesel in the world is going to hurt it. Before that I ran the stuff from home depot for a few years. It will start to tint after a few years, then change it. No biggie- costs all of 5 minutes and $2. If you let it go a decade, you get what you just had, a small leak that took what- 5 minutes to find?

If you add a fuel pressure gauge, inline from ffm to ip is ideal.

Two best things to do for future diagnostics of fuel system.

Do you have a link to that fuel line?

 

[Will L.]

No, I had a friend that bends wrenches on helos and planes. I just was visiting and saw he had some there and he gave me a some. The one I have is rienforced braided, so not as nice to see through as the completely clear stuff. Finding a supplier that has clear viton is the key. Most suppliers only sell entire rolls and since it is not cheap...

I made a couple phone calls this morning and am waiting for responses.

@Burning oil - I was thinking you started carrying clear viton to resell by the foot- or was that just me wishing?

 

[Husker6.5]

Try Speedway Motors for the clear viton fuel line, they may sell it by the foot or short lengths like 3' or 5'.