Community Forums

campnrace · 03-04-2021, 07:35 PM

I'm not sure, but in most cases there is a strainer on the pick up tube in the tank, it could also be plugged. Another thing to consider, in most cases, to get rid of algae it is separated from the fuel and trapped in the filters. If there was allot of algae, it will plug allot of filters.

geordi · 03-04-2021, 09:06 PM

The Xtool scanner that I linked (back on like page 3) can read more codes and more accurately than the Scangauge. I had tried the Bluefire and it DID NOT do what I wanted - which is read the stored codes. The bluefire (like the Scangauge D) seems only able to read "live" codes which are available while the problem is happening, but NOT read stored codes. Also I have discovered with my scangauge that it is not always able to clear the codes properly - but the Xtool did.

Fffrank · 03-05-2021, 06:37 AM

You should also remove the output line from filter #2 and see if you get a steady stream of fuel when the lift pump comes on.

JerryLook · 03-05-2021, 06:56 AM

^I did that a few days ago and I did not get a steady stream. I think today I’ll prefill both filters and try again.

I’m kind of leaning towards the lift pump not being able to prime the system, but that still wouldn’t explain the engine shutting off. I’m still looking for the smoking gun. I will cut the element out of the primary filter today and see what’s inside.

campnrace · 03-05-2021, 07:01 AM

Jerry, if you do not have ample fuel supply, your engine will quit. From everything you have done and reported this far, it sounds like there is a blockage.

zmotorsports · 03-05-2021, 07:29 AM

Quote:

Originally Posted by Fffrank

Of course, the problem is after 3 weeks of full-timing my unit is starting to feel like home. Got a ping of rig envy when we were parked next to a 2020 Dutch Star in SLC but otherwise I love my coach.

Quote:

Originally Posted by Mile Marker 42

LOL, you'll have that as long as you own your coach. I'll make you feel better. That 2020 Dutch cost $300K to over $500K to do the exact same thing as your coach. What did you pay for your coach again? Exactly.

The trick is to not give in to impulse purchase. We had some friends stay with us last summer and park their 2020 Dutch Star in our back yard for a couple of days while traveling through the area. Great looking coach. Then about a week later another friend stopped by with his new Newell that had me drooling all over myself.

I started looking at various older Newell's and a few Prevost conversions thinking I could get an older one and fix it up to my liking but then I came to the same conclusion, they go to the same places that I go to in my old Dynasty. I know my Dynasty like the back of my hand and have done a good job keeping it maintained so I stopped looking and just decided to enjoy my paid for coach and keep saving up to upgrade closer to retirement. It's fun to look but I've had to convince myself these new ones can't do anything I can't do in my old coach.

Quote:

Originally Posted by campnrace

I'm not sure, but in most cases there is a strainer on the pick up tube in the tank, it could also be plugged. Another thing to consider, in most cases, to get rid of algae it is separated from the fuel and trapped in the filters. If there was allot of algae, it will plug allot of filters.

When my uncle had fuel starvation issues in his old Beaver Marquis we tore the fuel tank out and found a lot of floating foil seals in the tank from the previous owner who obviously didn't peel them all the way off of fuel additives. They found their way into the tank and one even made it to the fuel supply hose. We found the one in the line by disconnecting each line individually and blowing a small amount of compressed air through each one into a rag to see what came out. We had a foil seal come out into the rag.

Once we cleaned the tank and reinstalled and reconnected all of the lines the coach ran perfectly again and did so for the next several years without falter.

I would definitely suggest working back towards the tank until you get good fuel flow from the lift pump to the filter and ultimately the CAPS pump before doing damage to the CAPS pump. I wouldn't fill the filter from an outside source just prior to the CAPS as that is the last defense before introducing debris into the injection pump.

Best of luck.

JerryLook · 03-05-2021, 07:41 AM

Primary filter. I still don’t think this is enough to stop the engine. Both of my filters are 10 micron, so this one should have stopped most of the junk from reaching the secondary. I’m getting more filters today, and will change the secondary anyways.

JerryLook · 03-05-2021, 07:46 AM

Also two things. I’ve read that the big diesel tanks don’t usually have a sock on the end of the pickup tube. Is this usually true?

Also if I do have to get to my tank it’s going to suck. It’s right in the center of the RV. I can see the fuel lines going into the top of the tank if I look from the front. The connections are towards the back of the tank (on top), and I have to use my phone to take a pic of the connections.

Early on I tried to get the lift pump to suck fuel out of a can of diesel right before the primary filter. It would start to suck it out, and then all the fuel would run back into the can as soon as the lift pump stopped.

I also sucked fuel out of the tank (again at the primary filter) with my little Harbor Freight drill pump. It did suck out a decent volume of fuel, but took a long time to suck it from the tank.

I might disconnect some lines and blow some air through them. I’ve already blown through the tank vent tube. And I know that’s clear at least.

zmotorsports · 03-05-2021, 08:00 AM

I've only worked on a few RV fuel tanks in my years and I've seen one with a mesh sock and a couple without anything but the pickup tube.

I had a lift pump on my ISL have a faulty check valve several years ago. It kicked my butt diagnosing and I was suspecting a pick up tube issue. I removed connectors at various points throughout the system and blew air through them but they all appeared to be clear. It would stumble at high revs going up grades so I knew it was a fuel starvation issue. Changed filters in the campground (I carry spares) and no change on the drive home. I babied it and could back off the throttle enough to clear the condition. Never did get any codes.

Upon arriving home is when I checked filters again and they were discovered to be clean and the originals were not bad at all after cutting them open to inspect. That's when I started going line by line and found nothing. I removed the lift pump as this was my second lift pump. It was not leaking but upon checking it on the bench I could get very little flow through it. I hit it with some reduced compressed air and heard a pop sound. After that I connected it to a supply and powered it up and it flowed fantastic. Evidently the internal check valve had become either dislodged, hung up or restricted slightly and would not allow full flow through it.

Rather than risk it I installed another new Cummins OEM lift pump and it has worked perfectly ever since. That was about 40k-45k miles ago.

I am installing a FASS system now as preventive measures to protect my CAPS pump but the OEM fuel system is functioning perfectly.

JerryLook · 03-05-2021, 08:31 AM

So I’m wondering about my lift pump check valve. I took the two port plugs out yesterday, and I can feel no moving parts to the check valve. Where did you blow air through yours?

Right now I’m trying to pull fuel from a can in front of the primary filter (to rule out a clog coming from the tank). The lift pump will suck fuel out of the can, but as soon as it turns off fuel runs back into the can. Not all of it, but about half the lines worth.

JerryLook · 03-05-2021, 08:48 AM

After running my lift pump for 30 times (around 30 seconds each time) I looked at my secondary filter and it’s only half full.

campnrace · 03-05-2021, 08:54 AM

hold the filter element up to a light and look through it, can you see light through the element?

I would spin 2 new filters on, use your auxiliary fuel supply and see if the lift pump will charge the system. If it does, I would remove the supply line from the tank and use compressed air and see if there is a blockage, as said, trap the debris in a rag.

Once you sort this out it would be wise to install a pump up at the tank to push the fuel.

campnrace · 03-05-2021, 08:56 AM

sounds like your lift pump is faulty to me, is this with new filters?

zmotorsports · 03-05-2021, 09:24 AM

Quote:

Originally Posted by JerryLook

So I’m wondering about my lift pump check valve. I took the two port plugs out yesterday, and I can feel no moving parts to the check valve. Where did you blow air through yours?

Right now I’m trying to pull fuel from a can in front of the primary filter (to rule out a clog coming from the tank). The lift pump will suck fuel out of the can, but as soon as it turns off fuel runs back into the can. Not all of it, but about half the lines worth.

I blew air through the lift pump manifold inlet where the line connects. I used about 30 PSI compressed air when I heard the audible pop. I didn't get any debris out of it so I was assuming it was either dislodged or just stuck partially in it's range of travel. This is also where I drew fuel in while I was bench testing it.

Immediately afterwards mine appeared to be working fine on the last bench test and flowed nearly a full stream of fuel but I opted to replace it because it is such a "fun" component to change. This was my second lift pump on my coach since I owned it. The first one was leaking when we purchased the coach in 2007 with 55k miles on it. I figured it was due to the newly released ULSD which caused the leak through the electrical connector as the manifold bolts were tight. I replaced it with the newly designed Cummins lift pump in 2007. It worked find until around 2014 or 2015 when I had the check valve issue and replaced it again.

I had contacted Cummins tech and they told me it was impossible for the check valve to stick as they had never seen that. I told the tech service guy that just because they had never seen it doesn't mean it isn't possible. I'm a mechanic and I've seen many things over the years that the engineers said weren't possible. One of them being dislodged check valves, especially in hydraulic or air systems. These simple disc and spring style of check valves are usually held in place with snap rings and I have seen quite a few of those cant in their bore or stick due to debris over my 30+ year career.