Fuel Return

bascars · **Joined:** Mon Jun 24, 2019 11:18 pm **Posts:** 23

Just went for a drive and when I stopped there was smoke coming out from under the hood and a strong diesel smell. Wasn't difficult to spot the return line on injector 1 partially off the nipple. Slipped it back on and started the motor. Immediately popped back off. I flipped the line around thinking it would help me determine if the line was just weak in that spot. Popped off in the same location (not the same side of the hose). This line runs through all the injectors and into the 4 way plastic distribution block which, in part, leads back to the fuel tank. It blew air through the return line at injector 1 with the engine off and it seemed air was going through. Not sure if it would do the same with motor running. Are there check valves in this plastic block that may have failed causing the pressure that is pushing the return line off? I left the Jeep about 30 minutes away and trying to see if I can replace something and drive home or if I need to trailer it home. Any thoughts on what could be causing this high pressure?

flash7210 · **Posted:** Sun Oct 04, 2020 8:45 pm

You might just need a new set of return lines.
The rubber and plastic gets brittle with age.

WWDiesel · **Posted:** Sun Oct 04, 2020 9:29 pm

There is no check valve in the plastic junction block!
There should be no pressure build up in the return side system, it is simply dumping excess back to fuel tank.

Some of the earlier Chevy Duramax engines used the same return line parts on their diesels and is much cheaper if you want to replace all the parts.
Comes with new clips, "Tee" fittings, and hose.
DIPACO RTF26410 FUEL INJECTOR RETURN LINE KIT LLY LBZ LMM DURAMAX DIESEL :google:

bascars · **Joined:** Mon Jun 24, 2019 11:18 pm **Posts:** 23

Thanks for the input. I'll replace and see what happens.

krb · **Posted:** Wed Oct 07, 2020 6:09 am

Good to know on the duramax interchange.

After I replaced my headgasket mine started popping off after about 30 miles. I guess they weren’t fully seated? 7K later - so far so good.

Just those clips alone are pretty pricey!

bascars · **Joined:** Mon Jun 24, 2019 11:18 pm **Posts:** 23

Ordered the replacement parts. Still waiting for them to come in. In the meantime I placed a new line (just something I had laying around) on the Jeep and it still popped off. It did take 10 seconds to pop off instead of one second with the old part. I put a small clamp on that end and the other end started to drip fuel. I placed a clamp on both ends and the hose connection on injector one started to come off again. While I wait for the full replacement of that system, just a question-is there any way that the injector seals could have damage causing excessive pressure at the return fitting? Not sure how they are built. I don't notice any difference in the way the Jeep is running that would indicate a problem there.

bascars · **Joined:** Mon Jun 24, 2019 11:18 pm **Posts:** 23

While taking the lines off to replace the fuel return lines I found a check valve between injector 4 and the return line bridge. It's black plastic with an arrow and 2.2 marked on it. I can't blow through either end so that makes sense why there is pressure backing up. I'll find a replacement and report back.

TKB4 · **Posted:** Wed Oct 28, 2020 8:08 pm

I have removed several different sets of fuel return lines and had a couple fitting break. I have not had any check valves on any of the fuel return line s I have dealt with (7 different ones. That could be part of your problem. Maybe you could post some pictures of it. I couldn't find reasonably priced clips either nut recently ID parts had them for about $3 I think. When Putting old ones back on a lubricant helps a lot I used No OX I had around vaseline also may work or grease. If the clips are installed correctly they should not be able to just pop off. Another member posted a helpful hint about a month ago about tying a string to the clips to help locate them in case they go flying off when inserting (I used dental floss). You can also put the clips on before you insert the fittings. The hose stays on those fittings very well without any clamp etc.
Let us know how you eventually get it fixed!

bascars · **Joined:** Mon Jun 24, 2019 11:18 pm **Posts:** 23

Interesting that you have never seen a check valve in the system. It was very difficult to locate anything online. I actually only found one used one on ebay. I had trouble posting pics last time so I will put a link to the ebay pic. I ended up buying one on amazon-link below (not sure why it is not creating links-may need to cut and paste). It was hard finding one small enough. Now you got me doubting if I should even install it.

https://www.ebay.com/itm/383313927981?c ... a7EALw_wcB

https://www.amazon.com/gp/product/B07NT ... UTF8&psc=1

WWDiesel · **Posted:** Thu Oct 29, 2020 2:17 pm

Not really sure why it needs a check valve on the fuel return line from the injectors, but the parts diagrams do show one. PN: 05093923AA
They simply call it a "valve".

bascars · **Joined:** Mon Jun 24, 2019 11:18 pm **Posts:** 23

Thank you for the diagram.
As I continued to pull the return line from the check valve to the junction block (wanted to replace all the old hose) I found what may have been the contributing factor in all this. The last item replaced before this occurred was the t-map sensor. Couldn't figure out if/how this could have been linked. Seems I pinched the return hose somehow between the sensor and the manifold. :banghead:

Certainly would have caused the pressure back up. Not sure if it could have damaged the check valve but the new one should arrive today. Hope to have everything back together by the end of the weekend.

WWDiesel · **Posted:** Fri Oct 30, 2020 12:16 pm

bascars wrote:

Thank you for the diagram.
As I continued to pull the return line from the check valve to the junction block (wanted to replace all the old hose) I found what may have been the contributing factor in all this. The last item replaced before this occurred was the t-map sensor. Couldn't figure out if/how this could have been linked. Seems I pinched the return hose somehow between the sensor and the manifold. :banghead:

Certainly would have caused the pressure back up. Not sure if it could have damaged the check valve but the new one should arrive today. Hope to have everything back together by the end of the weekend.

Glad it turned out to be something simple. We sometimes tend to go straight to complected on these engines and thus overlooking the sometimes simple problems. :banghead:

Post your final results, it may help someone else down the road.... :POPCORN:

bascars · **Joined:** Mon Jun 24, 2019 11:18 pm **Posts:** 23

So true that we jump to something complicated. Put in new fuel return. Broke one of the plastic tees (injector 4) while installing the check valve. Replaced with one of the originals. All back up and running. Thank you for all the input from forum members!

Onto the next project...

Fuel Return

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