Fuel system/ return line questions???
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Freshman User
Joined: Nov 2006
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Fuel system/ return line questions???
Few questions:
1. Can a small leak in the fuel return lines system (or injector line to injector) cause a stumble/miss at low rpm (1k-1.5k)? talking about a leak that is small enough not to be seen, but I assume is there.
2. Is it beneficial to use teflon tape so something of the sort to seal the injector line to the injector (small amount). Especially if the threads on the injector or injector line fitting are semi-buggered up?
3. I know a lot of people have problems with the return line o rings shrinking (or not sealing well) and causing air intrusion/leaks in the return system. Do you think a fuel additive like Power Service (grey bottle or white bottle), or Howes would help to keep not only the fuel system lubricated but also keeps the rings from shrinking?
4. Is there any fuel additive that could be run that would slightly swell the o-rings to cause them to seal better?
5. Would there be any benefit to using worm-gear style clamps on the return line setup instead of the regular red spring style clamps? I know that you would have to take care not to crank on them extremely hard so that they wouldn't cut into the hose, but it seems like you can be better assured that the clamp is tight with these (I hate spring style clamps... don't know why).
6. What type of clear hose are you guys using to check for air intrusion in your system. I know that most run it from the filter head to the 1st return line, but are you using some form of clear fuel line or chemical resistant line? If so, where are you getting it? It would seem to me that regular clear tubing would be eaten up by diesel fuel fairly quickly.
Some of these questions apply to my truck, and some are just for my personal information. Any informative responses are appreciated!
1. Can a small leak in the fuel return lines system (or injector line to injector) cause a stumble/miss at low rpm (1k-1.5k)? talking about a leak that is small enough not to be seen, but I assume is there.
2. Is it beneficial to use teflon tape so something of the sort to seal the injector line to the injector (small amount). Especially if the threads on the injector or injector line fitting are semi-buggered up?
3. I know a lot of people have problems with the return line o rings shrinking (or not sealing well) and causing air intrusion/leaks in the return system. Do you think a fuel additive like Power Service (grey bottle or white bottle), or Howes would help to keep not only the fuel system lubricated but also keeps the rings from shrinking?
4. Is there any fuel additive that could be run that would slightly swell the o-rings to cause them to seal better?
5. Would there be any benefit to using worm-gear style clamps on the return line setup instead of the regular red spring style clamps? I know that you would have to take care not to crank on them extremely hard so that they wouldn't cut into the hose, but it seems like you can be better assured that the clamp is tight with these (I hate spring style clamps... don't know why).
6. What type of clear hose are you guys using to check for air intrusion in your system. I know that most run it from the filter head to the 1st return line, but are you using some form of clear fuel line or chemical resistant line? If so, where are you getting it? It would seem to me that regular clear tubing would be eaten up by diesel fuel fairly quickly.
Some of these questions apply to my truck, and some are just for my personal information. Any informative responses are appreciated!
Logistics Pro
Joined: Sep 2007
Posts: 3,737
Likes: 179
From: Western Mass
I'll answer what I _think_ I know (and may not be true).
> 2. Is it beneficial to use teflon tape so something of the sort to seal the
> injector line to the injector (small amount). Especially if the threads on
> the injector or injector line fitting are semi-buggered up?
No, teflon is slippery, my understanding is it does almost nothing at all for sealing. What it does do, is lubricate the threads on pipe fittings so its easier to tighten them to a point that the THREADS seal the joint. The injector lines use a FLARE fitting which puts pressure on the line against the machined surface of the injector. If it doesn't seal and the nut is properly tightened, or minimally over tight, the fitting or line is messed up, especially if the threads are buggered up. Replace the line and or injector to fix.
> 3. I know a lot of people have problems with the return line o rings
> shrinking (or not sealing well) and causing air intrusion/leaks in the return
> system. Do you think a fuel additive like Power Service (grey bottle or
> white bottle), or Howes would help to keep not only the fuel system
> lubricated but also keeps the rings from shrinking?
> 4. Is there any fuel additive that could be run that would slightly swell the
> o-rings to cause them to seal better?
Possibly, but I doubt that would really help. Use better quality viton o-rings, and don't touch the lines. A pack of 50 o-rings from McMaster-Carr costs like $6, thats 3 complete sets of o-rings. Fuel additives are closer to $10 a bottle, which only covers a couple tanks of fuel (a few weeks driving). Even replacing the o-rings weekly would be cheaper than paying for fuel additive...
> 5. Would there be any benefit to using worm-gear style clamps on the
> return line setup instead of the regular red spring style clamps? I know
> that you would have to take care not to crank on them extremely hard so
> that they wouldn't cut into the hose, but it seems like you can be better
> assured that the clamp is tight with these (I hate spring style clamps...
> don't know why).
No, worm gear style clamps would actually be worse in this application. The problem is, when they get smaller, you have a flat section under the worm gear. Hoses are round, not flat, and that flat section will leak worse the more you try to tighten the clamp. This isn't a problem on larger coolant hoses because of their larger diameter. Its also why you see a deeper smooshed section of hoses where the gear is. Plus you are more apt to break the plastic barb off the caps tightening them. Spring clamps hold a near constant force across their entire circular shape. Some engines use them on coolant hoses, they hold the hose just fine. What happens is the hose deteriorates and thus leaks.
> 2. Is it beneficial to use teflon tape so something of the sort to seal the
> injector line to the injector (small amount). Especially if the threads on
> the injector or injector line fitting are semi-buggered up?
No, teflon is slippery, my understanding is it does almost nothing at all for sealing. What it does do, is lubricate the threads on pipe fittings so its easier to tighten them to a point that the THREADS seal the joint. The injector lines use a FLARE fitting which puts pressure on the line against the machined surface of the injector. If it doesn't seal and the nut is properly tightened, or minimally over tight, the fitting or line is messed up, especially if the threads are buggered up. Replace the line and or injector to fix.
> 3. I know a lot of people have problems with the return line o rings
> shrinking (or not sealing well) and causing air intrusion/leaks in the return
> system. Do you think a fuel additive like Power Service (grey bottle or
> white bottle), or Howes would help to keep not only the fuel system
> lubricated but also keeps the rings from shrinking?
> 4. Is there any fuel additive that could be run that would slightly swell the
> o-rings to cause them to seal better?
Possibly, but I doubt that would really help. Use better quality viton o-rings, and don't touch the lines. A pack of 50 o-rings from McMaster-Carr costs like $6, thats 3 complete sets of o-rings. Fuel additives are closer to $10 a bottle, which only covers a couple tanks of fuel (a few weeks driving). Even replacing the o-rings weekly would be cheaper than paying for fuel additive...
> 5. Would there be any benefit to using worm-gear style clamps on the
> return line setup instead of the regular red spring style clamps? I know
> that you would have to take care not to crank on them extremely hard so
> that they wouldn't cut into the hose, but it seems like you can be better
> assured that the clamp is tight with these (I hate spring style clamps...
> don't know why).
No, worm gear style clamps would actually be worse in this application. The problem is, when they get smaller, you have a flat section under the worm gear. Hoses are round, not flat, and that flat section will leak worse the more you try to tighten the clamp. This isn't a problem on larger coolant hoses because of their larger diameter. Its also why you see a deeper smooshed section of hoses where the gear is. Plus you are more apt to break the plastic barb off the caps tightening them. Spring clamps hold a near constant force across their entire circular shape. Some engines use them on coolant hoses, they hold the hose just fine. What happens is the hose deteriorates and thus leaks.
Senior User
Joined: Jun 2010
Posts: 103
Likes: 0
From: Duluth Georgia
well my truck dosent stumble. Hell it dosent even run now, the tank pressurises and shoots diesel out of the filler neck. new lift pump new filter, and the selector switch is bypassed.
cut the bed off and im replacing the lines.
cut the bed off and im replacing the lines.
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