Community Forums

Dark Sky · 06-10-2017, 01:52 PM

I need some advice or info on getting the air purged from my injectors. I changed the fuel-water separator for the first time. I filled it with diesel fuel and installed it as specified. There are no visible leaks. When I changed the fuel filter earlier, I simply hit the key and waited about 20 seconds, then turned the key off, and repeated maybe 5 times. It started right up and ran well. Today I finally got to the separator but no luck at all. I have done the key trick at least 15 times, to no avail.
I noticed what looked like a vent on the separator mounting boss, so I opened it (I think, loosened it about a full turn) and tried again, same bad result. I tightened it back up, tried another 5 key hits, still nothing, so I thought it's time to check in with the experts here.
Any suggestions? Keep on trying? Is there a purge opening higher up on the engine?
One other notable point; the boss for the separator has a small black rubber flapper on it. While I was wiping the gasket surface clean, I disturbed it, and a small amount of diesel fuel came pouring down. This may be where I really set myself back.
Any help to offer? Thanks very much for your time!

Skip426 · 06-10-2017, 07:14 PM

There has been some discussion about the , lift pump cycle ; on key on ; some years the lift pump ran up to three key cycles , before it requires seeing the starter being bumped to reset and allow the 30 sec run cycle .
Others say the pump requires the starter be bumped after the first cycle of the key to run the 30 seconds, on the second turning of the key.
I'd say have a helper turn the key on and be in a place to hear the pump run.
Any chance you could post a picture of the filter housing where you got the fuel to run out.

Dark Sky · 06-10-2017, 07:39 PM

Thanks for the response Skip! I do have a photo on my phone and will transfer it onto my drive and then share it here. Usually takes me some time to do this. Meanwhile, I have been searching the web and of course this site and read about some interesting solutions including pressurizing the fuel tank with air.... which requires 2 people. Tomorrow I will remove the separator and see if it needs to be re-topped up with diesel, then will try again using your suggested cycle-crank times.

Dark Sky · 06-10-2017, 07:48 PM

Here's the picture.

Dark Sky · 06-10-2017, 07:50 PM

Picture failed to attach, probably too large at 4.5 mb. I'll figure out how to save it smaller, back soon.

Dark Sky · 06-10-2017, 08:04 PM

Picture maybe attached.... ok, another fail. I saved it down to about 700k but still no go. I'll do some more reading on posting photos, which I've done successfully before.

Dark Sky · 06-10-2017, 08:20 PM

Yet another try, sized down to less than 100kb. Shows in the preview. You can see the small rubber flapper held in place by a single fastener on one side.

Playtime III · 06-11-2017, 09:01 AM

Similar issue just this week. Changed both fuel filters (secondary first). When I removed the primary I heard suction sound like fuel was returning to the tank. I did the key on 30 sec, reset 5 sec, key on 30 sec, reset 5 sec for 8 cycles. Cranked for 5 secs then I stopped. Ugh, no start.

Finally, after 5 cranking cycles she finally caught. Good as the chassis batteries were starting to sound like they were going to give up trying to start the ISL.

I did not have this issue the last filter change.

Dark Sky · 06-11-2017, 11:25 AM

Posting for the benefit of anyone who has the ISB 6.7 - Freightliner XC combination which seems pretty common for us low-end folks....
Thanks to Skip for advice, and also thanks to Playtime for chiming in.

-First, I managed to get a lot of air in the system, not sure if I could have done it any worse. Also, I only had about a half tank of fuel showing, so maybe really only about a third of a tank on hand, so conditions were definitely stacked against me. I scoured the forum and watched several Youtubes, never could find anything on my exact setup. Anyway...

-This morning I did exactly three things differently, and am now confident I can prime this thing whenever I have to. First, I removed the separator and checked the level. Sure enough, it was down about 1 1/2". I carefully topped it up and reinstalled. Second, I removed the fuel cap, having read this makes it easier for the lift pump to perform. Third, after going through 3 key taps to run the lift pump, (supposed to run 18 seconds, unconfirmed), I cranked the engine for 30 seconds. I have only been hitting it for about 8 or 10 seconds. On the second run through it caught and ran.

It appears the little rubber flapper on the separator mounting boss was not an issue. The motor has a cleaner idle and is running smoother than it has since I bought it. Luckily for me, this setup is an extremely easy air purger. I was really worried after reading what some other folks had to go through. Another thing I learned, my filter as specified by Cummins was exactly correct. In ignorance, I bought the separator that was specified by Cummins. It looked different and I called them back to confirm and they assured me it was correct. I installed it a few days ago and of course it leaked and that's when the nightmare began. I now know that the separator was provided and installed by Freightliner. The correct part is now installed and I can move on to the next great challenge.

Thanks again for your time in responding.

MoonchaserTX · 06-11-2017, 10:44 PM

This thread is great and may be the solution to my problem also.

Please see my thread also in the Cummins forum section titled "2009 Cummins 340 ISB-front engine diesel Freightliner motorhome wont start when warm"

Does it sound like the same issue to you?

I am taking the motorhome into Freightliner/Cummins service shop in Howe TX in the morning (Monday 6/12/17) and am worried about how many hours a service shop may spend diagnosing the problem so any commens/suggestions you may have would be great!!

Thanks much

Dark Sky · 06-12-2017, 07:30 AM

Just read your post. First, I'm no expert, have rv'd many years but this is my first diesel bus and I'm still learning about it.

-Your rig started and ran okay for 500 miles, whereas my problem was immediate (and self inflicted). As another poster suggested, I do think it wouldn't hurt to check that the filters are both tight enough, quick & easy.
-Cold starts are good but warm starts are not. I have to think this is something else.

It's good that you can still start and move the rig, and get into the shop. Hopefully the guys at Howe can catch a code and/or have the experience to get to the bottom of it quickly. Prevailing rate around Houston is $125/hr so money does get gobbled up.
Please post the rest of your story. I am very interested in learning the cause and resolution of your issue.

Thanks!

MoonchaserTX · 06-12-2017, 11:19 AM

You bet ... I'll update. So far it is sitting at the Howe TX freightliner/Cummins shop. They immediately diagnosed it as caused by the Wix fuel filters. Said on Cummins engines should only use Cummins filters. They are going to replace the fuel filter and water separator, and purge the air out of fuel lines. should be done tue morning. Will advise if that works after picking up.

MoonchaserTX · 06-12-2017, 11:25 AM

They are also going to pull be the diagnostic codes. Should I have that done before or after fuel filters are installed?

MoonchaserTX · 06-12-2017, 05:58 PM

They replaced the fuel filter and separator today and advise it starts up like it should. They are going to try it first thing in the morning and throughout the day Tuesday to ensure it is fixed.

They checked the codes and there were none, old or new so that aligns with the fact that no lights (even "wait to start" light) have come on since last time codes were checked and cleared.

Keeping fingers crossed we pick it up tomorrow with a relatively low impact bill and hope the only problem was fuel filters.