jleamont Report post Posted November 18, 2016 Glenn, pull your floor and snap a picture of the injection pump and the lines. I will be able to identify it. wheni went into Quickserv and pulled up my engine by serial it showed me my CAPS system and the same photo you attached above . I have heard of injection pump problems with the HPCR design also, but I believe it was caused by the new fuel rather than low pressure. What is the fuel like made of between the tank and primary filter? Is it a plastic tube or rubber hose? Share this post Link to post Share on other sites
jleamont Report post Posted November 18, 2016 The reason I asked about the fuel lines, if rubber they are notorious for failure where they draw air and the engine will stall at idle. If you put the pump at the tank and we're sending fuel up to the primary filter, if you had a pin hole in a line you would know it and fast! With a better pump sucking fuel you may have the same problem you currently have. I'm sure we can get it figured out but we will have to start with the basics first. Here is what the rubber lines look like you can see them connecting to my old primary filter Share this post Link to post Share on other sites
manholt Report post Posted November 19, 2016 Rich. Me also! I have no issue with the, why and where, on Joe's modification, but now I'm totally lost. gglenn. I understand what you have done, just not the why? Since even you're in doubt, why have you not taken the coach to Cummins, to verify if you are a CAPS II ? I also, wonder about the higher, way higher psi... Carl Share this post Link to post Share on other sites
gglenn Report post Posted November 19, 2016 Tow to Cummins, cost? Cummins troubleshooting bill, parts? Many have paid $$ just to replace the bad lift pump that may end up in the same state down the road. Many have driven off from Cummins/Alternate shop with the same problem they started with, back to shop. Guessing between a tow, and Cummins bill I'd have spent even money at this point. Although, more of my time. And Cummins fix, would not include the AirDog.. The AirDog and FASS systems are put on thousands of Diesel, so not sure why the why. Sorry restated multiple times what I have done with hoses. The Tank to AirDog is stock, it is hard nylon hose. All the rest have been replaced with new. AirDog removes any induced air, so it would mask a leak in that nylon hose now that system is revised. Some may think this solution doesn't work. The coach is running and staying running with new Airdog all done, it did not stay running prior. I have always said it is a CAPS II, folks keep asking if it's CAPS which is not CAPS II. Concerning higher psi, stock gear pump output is around 20psi at idle per cummins doc, AirDog is set the same, albeit it would put 20psi on Inlet of Gear Pump, but not higher as "Manholt" states above. Once above idle stock gear pump and fuel system pressure increase, so not completely sure what prompted the "much higher pressure" comment. But do concede 20 psi at Inlet of Gear Pump vs. stock design which Inlet is in vaccum. If your pump is the same as the one I attached from the remanufactured pump company that says CAPS II, it only has a single high pressure output to the common rail, ie Not 6 separate line outputs. Sorry, Pic above does not show your pump. Share this post Link to post Share on other sites
jleamont Report post Posted November 19, 2016 My pump is the one in the other photos (the black one, not silver). If your coach has nylon type of material on the fuel lines I am certain it's high pressure common rail, that design came at the same time, by coincidence the chassis manufacturers began to use at flex tubing for fuel line and followed the engine manufacturers and plumbed the chassis with the same product, it's actually cheaper and works better. Not sure where the term CAPS 2 came from, Cummins references it as HPCR which replaced CAPS. If you have the airdog set to the same output as the factory lift (primer) pump you should be fine. I would put a gauge on it just to be safe and keep an eye on it. What was changed on the return system? I kept the factory lift pump since part of it is a manifold to regulate the returning fuel to the tank from the injection pump and cylinder head (I.e excess from the injectors). I capped the ports that were to deliver fuel. I routed the line between the pump and the tank to a cooler, mostly in part since my fuel tank bay is now sealed off from air flow. Since the lift pump is really only a primer pump (as you mentioned earlier, by the way great observation). I am surprised yours was stalling at idle, when in theory the lift pump should be in bypass, unless that was the source of the air introduction, which is a good possibility but first I would want to confirm that as the root cause. Incidentally they were known to leak and introduce air into the fuel system. Is the oem pump wet where the housings join or around the electric portion where the motor mounts? Going the route you went should make that coach more dependable. For piece of mind I would want to be certain the root cause was the old lift pump just in case it wasn't, the road test could be costly. Take some photos and post them in the gallery, I would like to see the finished product. Share this post Link to post Share on other sites
gglenn Report post Posted November 19, 2016 Lift pump was likely not wet, but can't confirm it was the only problem. I suspect the fitting going into ECU cooler didn't help the whole situation either, since it's also one side of the lift pump connection point, given it is also check valve, small size passages, just very restrictive setup. Other ECU cooler port is similar but no internal check valve. Both fitting were removed/upgraded along with lift pump removal, so no longer a problem. Will do on photo's, first test drive will be up and down our long driveway a few times. Yes, was shooting for dependable vs. it works. Share this post Link to post Share on other sites
gglenn Report post Posted November 28, 2016 Install picture, attached! Mounting AirDog was the easy part of the install, the new hoses, fittings, and wiring took the most time. Recap: Mounted AirDog in the trans cooler/vented side door, Road side, just behind rear axle. It's a busy bay with hydraulic jack pump/hoses and Air bag control unit. Mounted Airdog pump in place of Monaco relocated Fuel/Water separator. Plumbing: Right side (Inlet) of AirDog is from Tank (stock nylon/hard fuel line/funky brass quick connect), small Blue/Red fitting just above is a new hose with "separated air" and it returns to Tank. Black fitting on left side of Airdog goes to back of engine fitting (normal port). Left side(Inlet) of stand alone Secondary filter is coming from Gear Pump portion of engine mounted pump, Right side (outlet) returns to High Pressure inlet of engine mounted pump. Excess fuel return (at back of engine) to tank was left stock (stock nylon/hard fuel line). Hoses from back of engine to ECU cooler and ECU cooler to Gear Pump inlet described in previous posts. Stock lift/prime pump (behind ecu cooler) removed. PS If you notice the WIF connector unplugged, I'm swapping AD supplied water separator with FG/Cummins water separator filter that has WIF sensor. The FG/Cummins filter will be FG19596, which is a finer Micron than the normal FG1003. AirDog_Done.pdf Share this post Link to post Share on other sites
