fuel return line replacement - some questions

[seacoats]

I just ordered a fuel return line kit from the nice folks over at Conestoga diesel. I was about ready to order the kit from ebay, but after doing some searching around the forum i realized how bad of an idea that might have been. One of my lines rubbed a hole in it and is spewing fuel onto the top of my block. I can't seem to find a walkthrough of how to go about replacing them. Does such a thing exist here? Am i crazy for not also replacing my injectors at this time? I'd like to start running wvo or wmo sometime in the next couple of months. Does this influence things? I presume that it goes without saying that the pop tested injectors are the way to go? Seems like that's the consensus here, but i'm still not sure why.

 

[icanfixall]

Good for you to buy from Conestoga Diesel. Mel and the crew there really know whats going on when you talk idi engines and fuel systems.. About the easiest way of doing this job is to match up one side when you make the new set. Please use an exacto knife to clean out the plastic flash from molding these caps from where the o ring frist touches the caps. It may not feel like it might cut the o rings but it has. Not all caps have a lot of this flash. Find a harbor freight store and buy a dental pick. They sell them is sets too. the different tips will help in geting the old o rings off the injectors. Be careful not to scratch the metal injector too. When installing new o rings install the top ring first. Then roll the lower one over the top one. It works great and you wont damage the o ring by installing it and then taking it out to install it in the lower slot. Once they are all in place grease them with any grease you have handy. KY is water based so don't use that. When thats done now press the caps down on the injector till you feel the second pop of it seating properly. Sometimes this is barely felt in your hand. Do not press down on the small hose nipples or they can break off. Keeping things clean is about all you need to know. If you want to change the direction of flow ask first. No matter what. the return line flow must be in a direction towards the fuel tank. now that can be from the back of the passenger side all the way around to the back of the drivers side. just made sure the flow ends up returning to the tank. That line off the filter filter is a return line to the tanks as is the line off the injection pump top.

 

[seacoats]

Thanks for the thoughtful and informative reply! I think that contains everything i need. Repair kit ought to be arriving in a couple of days. I'll either have more questions or a success story coming soon.

 

[seacoats]

My project was a success! The parts arrived in the mail from Contestoga Diesel.

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And i went to work replacing the fuel lines.

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All went well and i didn't run into any problems to speak of. Replaced it piece by piece, using the old lines as guides to cut out the new ones. The only worrying thing was the hardline on the injector in back right (when looking at the engine from in front) seems to have some carbon build up.

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I imagine that this means it's time for new injectors and if i'm gonna be doing that, i should probably switch to braided fuel lines. The projects never end.

 

[icanfixall]

Really not sure what you mean by the back hardline has some carbon buildup in it. Thats a really small hole to see anything in. The back cylinder on the drivers side of the engine is number 8. Every cylinder is marked by number on the intake ports at the head. Look near the 2 bolts that connects the intake to that cylinder on the heads.

 

[OLDBULL8]

None of your attachments work.

 

[seacoats]

Hrmmm. Attachments aren't working. I've uploaded a couple photos to imgur. You can see the difference in between the two. What i'm guessing is carbon is showing up as black crusty stuff on the angled part of the hardline where it terminates. Could an injector be bad and allow exhaust gasses to blow back through it and into the fuel system? Just a guess. Trucks running fine... Is not knowing the history and age of the injectors reason enough to replace them if they don't seem to be making the truck run poorly?

photos here
http://imgur.com/a/2yrVw#MVykI2Y

 

[USNENFTS]

So I think my return line from my IP goes to the wrong place. It goes to the first nozzle on the right back (looking from front) I feel as if it not supposed to go there? Or is it a return line from the nozzles to the IP? I may have to take a picture and post it later when I'm home this weekend.

 

[seacoats]

You might have more luck posting a new thread with some photos, i'm not how many people are reading all the replies to this thread. That being said, i just went and poked my head in my truck. On mine, the IP return line goes to the #2 injector. (#2 is the one closest to you on the right as your looking at the motor with the hood up) Also, as i learned from icanfixitalls post, all of the injectors are numbered. Here's a photo of how my return lines are routed.
http://imgur.com/gejxeLU
There are alternative ways of routing the lines. I'm not sure what the benefit of such things is, but just because yours looks different, doesn't mean it's wrong.

 

[USNENFTS]

Yeah, yours is just like mine. I re-did my whole fuel system about a year ago. New Injecotrs, Return Lines, Lift Pump, had my IP rebuilt.

 

[seacoats]

Did you do that all yourself? How difficult was it? Im eyeing some new injectors and fuel lines as the next project.

 

[icanfixall]

The return line from the top of the pump can go to any injector cap because its all in the return line system. Standing in front of the truck the cylinders on the drivers side from the radiator back to the firewall are 2-4-6-8. From the same direction on the passenger side its 1-3-5-7. Right between the 2 bolts that holds the intake to the head is the cast in cylinder numbers. The return line system has about 1 lbs pressure on it. At the end of the line in the tanks is a rubber flapper valve like some self baling boats have on the transom. On my engine is a hard line running down the drivers side of the intake manifold. Some truck engines have this and some don't.
If an injector leaks compression back up the line into the return system the plastic cap will melt from the combustion heat.

 

[seacoats]

Huh. Good to know about the caps melting. I didn't see any obvious signs of carnage on the caps when i replaced the return lines. Would the injector leak compression/exhaust gasses into the return line or into the fuel supply line? If it's going into the supply line would that still melt the return cap?